The Azul project contains the components that together serve as the backend to Boardwalk, a web application for browsing genomic data sets.

1. Architecture Overview

1.1 Components

Azul consists of two components: an indexer and a web service. The Azul indexer is an AWS Lambda function that responds to web-hook notifications about bundle addition and deletion events occurring in a Data Store instance. The indexer responds to those notifications by retrieving the bundle's metadata from said data store, transforming it and writing the transformed metadata into an Elasticsearch index. The transformation extracts selected entities and denormalizes the relations between them into a document shape that facilitates efficient queries on a number of customizable metadata facets.

The Azul web service, another AWS Lambda function fronted by API Gateway, serves as a thin translation layer between Elasticsearch and the Boardwalk UI, providing features like pluggable authentication, field name translation and introspective capabilities such as facet and entity type discovery.

Both the indexer and the web service allow for project-specific customizations via a plug-in mechanism, allowing the Boardwalk UI codebase to be functionally generic with minimal need for project-specific behavior.

1.2 Architecture Diagram

2. Getting Started

2.1 Development Prerequisites

• Python, the specific verson is defined in an environment variable called azul_python_version defined in environment.py

• The bash shell

• GNU make 3.81 or newer

• git 2.36.0 or newer

• Docker, for running the tests (the community edition is sufficient). The minimal required version is uncertain, but 19.03, 18.09, and 17.09 are known to work.

• Terraform, to manage deployments. Azul requires a specific version of Terraform, which is defined in a variable called azul_terraform_version in environment.py. Refer to the official documentation on how to install terraform. Terraform comes as a single, statically linked binary, so the easiest method of installation is to download the binary and put it in a directory mentioned in the PATH environment variable.

• AWS credentials configured in ~/.aws/credentials and/or ~/.aws/config

• git-secrets

• jq

• The build process relies on numerous utilities that are pretty much standard on any modern Unix. Things like perl, sort, comm, uniq, sed, cp, mv and rm.

• For VPN support: OpenSSL (version 1.1.10 and 3.0.5 are known to work but other versions should work, too). LibreSSL, which became the default on macOS at some point, is an acceptible replacement. Version 2.8.3 is known to work.

• Users of macOS 12 (Monterey) should follow additional steps outlined in Troubleshooting

• Users of macOS 11 (Big Sur) should follow additional steps outlined in Troubleshooting

2.1.1 git-secrets

git-secrets helps prevent secrets (passwords, credentials, etc.) from being committed to a Git repository. See the Installing git-secrets section of the project's README for instructions how to install git-secrets on your OS.

Once installed, git-secrets will need to be configured individually in each one of your existing clones, be they clones of this repository or any of the team's other repositories. Run

cd /path/to/clone
git secrets --install  # install the hooks

To register the provider that adds AWS-specific secret patterns, run

git secrets --global --register-aws

Optionally, to configure git-secrets in all repository clones created subsequently, run:

git secrets --install ~/.git-templates/git-secrets
git config --global init.templateDir ~/.git-templates/git-secrets

You must now verify the proper function of git-secrets in each one of your existing clones, be they clones of this repository or any of the team's other repositories:

1) Run cd /path/to/clone

2) Make sure there is no foo.txt in the current directory

3) Run (echo -e 'AWS_ACCOUNT_ID=00000000000\x30' > foo.txt && git add foo.txt && git hook run pre-commit); git rm -fq foo.txt

This must produce output containing [ERROR] Matched one or more prohibited patterns. If it doesn't, proper function of git-secrets has not been verified!

If you get git: 'hook' is not a git command. See 'git --help'., you are using an outdated version of git.

If you get error: cannot find a hook named pre-commit, git-secrets has not been configured for the clone.

If you get no output, the AWS provider has not been registered.

2.2 Runtime Prerequisites (Infrastructure)

An instance of the HCA Data Store aka DSS. The URL of that instance can be configured in environment.py or deployments/*/environment.py.

The remaining infrastructure is managed internally using TerraForm.

2.3 Project configuration

Getting started without attempting to make contributions does not require AWS credentials. A subset of the test suite passes without configured AWS credentials. To validate your setup, we'll be running one of those tests at the end.

1. Load the environment defaults

   source environment

2. Activate the dev deployment:

   _select dev

3. Load the environment:

   source environment

   The output should indicate that the environment is being loaded from the selected deployment (in this case, dev).

4. Create a Python virtual environment and activate it:

   make virtualenv
   source .venv/bin/activate

5. Install the development prerequisites:

   make requirements

   Linux users whose distribution does not offer the required Python version should consider installing pyenv first, then Python using pyenv install x.y.z and setting PYENV_VERSION to x.y.z, where x.y.z is the value of azul_python_version in environment.py. You may need to update pyenv itself before it recognizes the given Python version. Even if a distribution provides the required minor version of Python natively, using pyenv is generally preferred because it offers every patch-level release of Python, supports an arbitrary number of different Python versions to be installed concurrently and allows for easily switching between them.

   Ubuntu users using their system's default Python installation must install python3-dev before any wheel requirements can be built.

   sudo apt install python3-dev

6. Run make. It should say Looking good! If one of the check target fails, address the failure and repeat. Most check targets are defined in common.mk.

7. Make sure Docker works without explicit root access. Run the following command without sudo:

   docker ps

   If that fails, you're on your own.

8. Finally, confirm that everything is configured properly on your machine by running the unit tests:

   make test

2.3.1 GitHub credentials

Integration tests require a GitHub personal access token to be configured.

1. Log into your account on https://github.com/. Click your user icon and navigate to Settings -> Developer settings -> Personal access tokens

2. Click Generate new token

3. Enter an appropriate description such as "Integration tests for Azul"

4. Select No expiration

5. Do not select any scopes

6. Click Generate token and copy the resulting token

7. Edit the deployments/.active/environment.local.py file and modify the GITHUB_TOKEN variable:

   'GITHUB_TOKEN': '<the token you just copied>'

   Do not add the token to any environment.py files.

8. Repeat the previous step for any deployments you intend to use for running the integration tests.

2.3.2 AWS credentials

You should have been issued AWS credentials. Typically, those credentials require assuming a role in an account other than the one defining your IAM user. Just set that up normally in ~/.aws/config and ~/.aws/credentials. If the assumed role additionally requires an MFA token, you should run _login immediately after running source environment or switching deployments with _select.

2.3.3 Google Cloud credentials

When it comes to Azul and Google Cloud, we distinguish between two types of accounts: an Azul deployment uses a service account to authenticate against Google Cloud and Azul developers use their individual Google account in a web browser. For the remainder of this section we'll refer to the individual Google account simply as "your account". For developers at UCSC this is their …@ucsc.edu account.

On Slack, ask for your account to be added as an owner of the Google Cloud project that hosts—or will host—the Azul deployment you intend to work with. For the lower HCA DCP/2 deployments (dev, sandbox and personal deployments), this is platform-hca-dev. The project name is configured via the GOOGLE_PROJECT variable in environment.py for each deployment.

2.3.4 Google Cloud, TDR and SAM

The Terra ecosystem is tightly integrated with Google's authentication infrastructure, and the same two types of accounts mentioned in the previous section are used to authenticate against SAM and Terra Data Repository (TDR). Meaning that there are now at least two Google accounts at play:

1) your individual Google account ("your account"),

2) a service account for each shared or personal Azul deployment.

You use your account to interact with Google Cloud in general, along with both production and non-production instances of Terra, SAM, and TDR, provided you have access. You also use your account for programmatic interactions with the above systems and the Google Cloud resources they host, like the BiqQuery datasets and GCS buckets that TDR manages. For programmatic access to the latter, you can either gcloud auth login with your account or use the service_account_credentials context manager from aws.deployment.

In order for an Azul deployment to index metadata stored in a TDR instance, the Google service account for that deployment must be registered with SAM and authorized for repository read access to datasets and snapshots. Additionally, in order for the deployment to accept unauthenticated servce requests, a second Google service account called the public account must likewise be registered and authorzied.

The SAM registration of the service accounts is handled automatically during make deploy. To register without deploying, run make sam. Mere registration with SAM only provides authentication. Authorization to access TDR datasets and snapshots is granted by adding the registered service accounts to dedicated SAM groups (an extension of a Google group). This must be performed manually by someone with administrator access to that SAM group. For non-production instances of TDR, the indexer service account needs to be added to the group azul-dev.

A member of the azul-dev group has read access to TDR. An administrator of this group can add other accounts to it, and optionally make them administrators, too. Before any account can be added to a group, it needs to be registered with SAM. While make deploy does this automatically for the deployment's service account, for your account, you must follow the steps below:

1. Log into Google Cloud by running

   gcloud auth login

   A browser window opens to complete the authentication flow interactively. When being prompted, select your account.

   For more information refer to the Google authorization documentation.

2. Register your account with SAM. Run

   (account="$(gcloud config get-value account)"
   token="$(gcloud auth --account $account print-access-token)"
   curl $AZUL_SAM_SERVICE_URL/register/user/v1  -d "" -H "Authorization: Bearer $token")

3. Ask an administrator of the azul-dev group to add your account to the group. The best way to reach an administrator is via the #team-boardwalk channel on Slack. Also, ask for a link to the group and note it in your records.

4. If you've already attempted to create your deployment via make deploy, visit the link, sign in as your account and add your deployment's service account to the group. Run make deploy again.

For production, use the same procedure, but substitute azul-dev with azul-prod.

2.3.5 Creating a personal deployment

Creating a personal deployment of Azul allows you test changes on a live system in complete isolation from other users. If you intend to make contributions, this is preferred. You will need IAM user credentials to the AWS account you are deploying to.

1. Choose a name for your personal deployment. The name should be a short handle that is unique within the AWS account you are deploying to. It should also be informative enough to let others know whose deployment this is. We'll be using foo as an example here. The handle must only consist of digits or lowercase alphabetic characters, must not start with a digit and must be between 2 and 16 characters long.

2. Create a new directory for the configuration of your personal deployment:

   cd deployments
   cp -r sandbox yourname.local
   ln -snf yourname.local .active
   mv .active/.example.environment.local.py .active/environment.local.py 
   cd ..

3. Read all comments in deployments/.active/environment.py and deployments/.active/environment.local.py and make the appropriate edits.

2.4 PyCharm

Running tests from PyCharm requires environment to be sourced. The easiest way to do this automatically is by installing envhook.py, a helper script that injects the environment variables from environment into the Python interpreter process started from the project's virtual environment in .venv.

To install envhook.py run

make envhook

The script works by adding a sitecustomize.py file to your virtual environment. If a different sitecustomize module is already present in your Python path, its sitecustomize.py file must be renamed or removed before the installation can proceed. The current install location can be found by importing sitecustomize and inspecting the module's __file__ attribute.

Whether you installed envook.py or not, a couple more steps are necessary to configure PyCharm for Azul:

1. Under Settings -> Project—Interpreter select the virtual environment created above.

2. Set the src and test folders as source roots by right-clicking each folder name and selecting Mark Directory as → Sources Root.

3. Exclude the .venv, lambdas/indexer/vendor, and lambdas/service/vendor folders by right-clicking each folder name and selecting Mark Directory as → Excluded.

Newer versions of PyCharm install another sitecustomize module which attempts to wrap the user-provided one, in our case envhook.py. This usually works unless envhook.py tries to report an error. PyCharm's sitecustomize swallows the exception and, due to a bug, raises different one. The original exception is lost, making diagnosing the problem harder. Luckily, the sitecustomize module is part of a rarely used feature that can be disabled by unchecking Show plots in tool window under Settings — Tools — Python Scientific.

3. Deployment

3.1 One-time provisioning of shared cloud resources

Most of the cloud resources used by a particular deployment (personal or main ones alike) are provisioned automatically by make deploy. A handful of resources must be created manually before invoking this Makefile target for the first time in a particular AWS account. This only needs to be done once per AWS account, before the first Azul deployment is created in that account. Additional deployments do not require this step.

3.1.1 Versioned bucket for shared state

Create an S3 bucket for shared Terraform and Chalice state. The bucket must not be publicly accessible since Terraform state may include secrets. If your developers assume a role via Amazon STS, the bucket should reside in the same region as the Azul deployment. This is because temporary STS AssumeRole credentials are specific to a region and won't be recognized by an S3 region that's different from the one the temporary credentials were issued in. The name of the bucket is not configurable but instead dictated by Azul's internal convention for bucket names. Use the commands below to create that bucket.

_select dev.shared  # or prod.shared, anvildev.shared, anvilprod.shared …
bucket="$(python -c 'from azul.deployment import aws; print(aws.shared_bucket)')"
aws s3api create-bucket --bucket "$bucket"
aws s3api put-bucket-tagging \
          --bucket "$bucket" \
          --tagging TagSet="[{Key=owner,Value=$AZUL_OWNER}]"

3.1.2 Route 53 hosted zones

Azul uses Route 53 to provide user-friendly domain names for its services. The DNS setup for Azul deployments has historically been varied and rather protracted. Azul's infrastrcture code will typically manage Route 53 records but the zones have to be created manually.

Create a Route 53 hosted zone for the Azul service and indexer. Multiple deployments can share a hosted zone, but they don't have to. The name of the hosted zone is configured with AZUL_DOMAIN_NAME. make deploy will automatically provision record sets in the configured zone, but it will not create the zone itself or register the domain name it is associated with.

Optionally, create a hosted zone for the DRS domain alias of the Azul service. The corresponding environment variable is AZUL_DRS_DOMAIN_NAME. This feature has not been used since 2020 when Azul stopped offering DRS for HCA.

The hosted zone(s) should be configured with tags for cost tracking. A list of tags that should be provisioned is noted in src/azul/deployment.py:tags.

3.1.3 AWS Chatbot integration with Slack

Azul deployments can make use of an AWS Chatbot instance to forward messages from the SNS monitoring topic to a channel in a Slack workspace. Both the topic and the Chatbot instance are shared by all deployments that are collocated in one AWS account and that have monitoring enabled via the AZUL_ENABLE_MONITORING environment variable. Most of the AWS Chatbot integration is managed by Terraform but the following manual steps must be performed once per AWS account containing such deployments, before Terraform can take care of the rest. The AWS Chatbot integration can be enabled or disabled separately for each AWS account by setting the azul_slack_integration environment variable in the configuration for the main deployment in that account. If it is disabled in an account, these steps can be skipped in that account.

1. In the AWS Chatbot console, under Configure a chat client, select the Slack chat client option, then click the Configure client button.

2. Once redirected to Slack's authorization page, you may be prompted to sign in using your UCSC account, in order to provide permission for Chatbot to access the Slack workspace. When this step is completed, you should see the workspace name and ID listed in the console.

3. Use the ID displayed in the console to set the workspace_id attribute of the azul_slack_integration variable in the main deployment's environment file for that account.

4. Set the channel_id attribute to the ID of the appropriate channel. Get the channel ID by right-clicking the channel in Slack and selecting View channel details. The ID is listed at the bottom of the About tab.

3.1.4 Shared resources managed by Terraform

The remaining resources for each of the AWS accounts hosting Azul deployments are provisioned through Terraform. The corresponding resource definitions reside in a separate Terraform component.

A Terraform component is a set of related resources. It is our own bastardized form of Terraform's module concept, aimed at facilitating encapsulation and reuse. Each deployment has at least a main component and zero or more child components. The main component is identified by the empty string for a name; child components have a non-empty name. The dev component has a child component dev.shared. To deploy the main component of the dev deployment, one selects the dev deployment and runs make apply from ${project_root}/terraform (or make deploy from the project root). To deploy the shared child component of the dev deployment, one selects dev.shared and runs make apply from ${project_root}/terraform/shared. In other words, there is one generic set of resource definitions for a child component, but multiple concrete deployment directories.

There are currently two Terraform components: shared and gitlab. Interestingly, not every deployment uses these components. Typically, only the dev and prod deployments use them. The other deployment share them with dev or prod, depending on which of those deployments they are colocated with. Two deployments are colocated if they use the same AWS account. The shared component contains the resources shared by all deployments in an AWS account.

To deploy the remaining shared resources, run:

_select dev.shared  # or prod.shared, anvildev.shared, anvilprod.shared …
cd terraform/shared
make validate
bucket="$(python -c 'from azul.deployment import aws; print(aws.shared_bucket)')"
terraform import aws_s3_bucket.shared "$bucket"
make

The invocation of terraform import puts the bucket we created earlier under management by Terraform.

3.1.5 GitLab

A self-hosted GitLab instance is provided by the gitlab TerraForm component. It provides the necessary CI/CD infrastructure for one or more Azul deployments and protects access to that infrastructure through a VPN. That same VPN is also used to access to Azul deployments with private APIs (see AZUL_PRIVATE_API in environment.py). Like the shared component, the gitlab component belongs to one main deployment in an AWS account (typically dev or prod) and is shared by the other deployments colocated with that deployment.

The following resources must be created manually before deploying the gitlab component:

• An EBS volume needs to be created. See gitlab.tf.json.template.py and the section on CI/CD for details.

• A certificate authority must be set up for VPN access. For details refer to section on GitLab CA.

3.2 One-time manual configuration of deployments

In order for users to authenticate using OAuth 2.0, an OAuth 2.0 consent screen must be configured once per Google project, and an OAuth 2.0 client ID must be created for each deployment.

3.2.1 Google OAuth 2.0 consent screen

These steps are performed once per Google project.

1. Log into the Google Cloud console and select the desired project, e.g. dev or prod

2. Navigate to APIs & Services -> OAuth Consent Screen

3. Click CONFIGURE CONSENT SCREEN

4. For User Type, select External

5. Click CREATE

6. For App name, enter Azul {stage}, where {stage} is the last component of the Google project name, e.g. dev or prod

7. Provide appropriate email addresses for App information -> User support email and Developer contact information -> Email addresses, e.g. azul-group@ucsc.edu

8. Click SAVE AND CONTINUE

9. For scopes, select:

   https://www.googleapis.com/auth/userinfo.email
   https://www.googleapis.com/auth/userinfo.profile
   openid

10. Click SAVE AND CONTINUE twice

11. Click PUBLISH APP and CONFIRM

3.2.2 Google Oauth 2.0 Client ID

These steps are performed once per deployment (multiple times per project).

1. Log into the Google Cloud console and select the desired project, e.g. dev or prod

2. Navigate to APIs & Services -> Credentials; click + CREATE CREDENTIALS -> OAuth Client ID

3. For Application Type, select Web application

4. For Name, enter azul-{stage} where stage is the name of the deployment

5. Add an entry to Authorized JavaScript origins and enter the output from python3 -m azul config.service_endpoint

6. Add an entry to Authorized redirect URIs. Append /oauth2_redirect to the value of the previous field and enter the resulting value.

7. Click Create

8. Copy the OAuth Client ID (not the client secret) and insert it into the deployment's environment.py file:

   'AZUL_GOOGLE_OAUTH2_CLIENT_ID': 'the-client-id'

9. _refresh

3.3 Provisioning cloud infrastructure

Once you've configured the project and your personal deployment or a shared deployment you intend to create, and once you manually provisioned the shared cloud resources, it is time to provision the cloud infrastructure for your deployment. Run

make deploy

to prepare the Lambda functions defined in the lambdas directory for deployment via Terraform. It will display a plan and ask you to confirm it. Please consult the Terraform documentation for details.

Any time you wish to change the code running in the lambdas you will need to run make deploy.

Some Terraform configuration is generated by make -C lambdas, but the rest is defined in ….tf.json files which in turn are generated from ….tf.json.template.py templates which are simple Python scripts containing the desired JSON as Python dictionary and list literals and comprehensions. Running make deploy will run make -C lambda and also expand the template files. Changes to either the templates or anything in the lambdas directory requires running make deploy again in order to update cloud infrastructure for the selected deployment.

3.4 Creating the Elasticsearch indices

While make deploy takes care of creating the Elasticsearch domain, the actual Elasticsearch indices for the selected deployment must be created by running

make create

In a newly created deployment, the indices will be empty and requests to the deployment's service REST API may return errors. To fill the indices, initiate a reindexing. In an existing deployment make create only creates indices that maybe missing. To force the recreation of indices run make delete create.

3.5 Locating REST API endpoints via DNS

The HTTP endpoint offered by API Gateway have somewhat cryptic and hard to remember domain names:

https://klm8yi31z7.execute-api.us-east-1.amazonaws.com/hannes/

Furthermore, the API ID at the beginning of the above URL is likely to change any time the REST API is re-provisioned. To provide stable and user-friendly URLs for the API lambdas, we provision a custom domain name object in API Gateway along with an ACM certificate and a CNAME record in Route 53. the user-friendly domain names depend on project configuration. The default for HCA is currently

http://indexer.${AZUL_DEPLOYMENT_STAGE}.singlecell.gi.ucsc.edu/
http://service.${AZUL_DEPLOYMENT_STAGE}.singlecell.gi.ucsc.edu/

Personal deployments are subdomains of the domain for the dev deployment:

http://indexer.${AZUL_DEPLOYMENT_STAGE}.dev.singlecell.gi.ucsc.edu/
http://service.${AZUL_DEPLOYMENT_STAGE}.dev.singlecell.gi.ucsc.edu/

3.6 Private API

Follow these steps to put a deployment's API Gateway in the GitLab VPC so that a VPN connection is required to access the deployment. See 9.1 VPN access to GitLab for details. Read this entire section before following these steps.

1. Destroy the current deployment (make -C terraform destroy).

2. Increment AZUL_DEPLOYMENT_INCARNATION.

3. Set AZUL_PRIVATE_API to 1.

4. Redeploy (make deploy).

Going in the opposite direction i.e., attempting to change AZUL_PRIVATE_API from 1 to 0 will result in Cannot update endpoint from PRIVATE to EDGE during make deploy. The error message will be shown for every REST API separately. It should be sufficient to simply terraform taint the REST API resources mentioned in the error messages and then to run make deploy again. It is possible that this also works when changing AZUL_PRIVATE_API from 0 to 1. Try that first, before destroying the entire deployment.

Troubleshooting

Transient errors might be encountered during the deploy such as SQS Error Code: AWS.SimpleQueueService.NonExistentQueue. SQS Error Message: The specified queue does not exist for this wsdl version In such cases rerunning make deploy should resolve the issue.

If the error ResourceAlreadyExistsException: The specified log group already exists is encountered, follow the steps below to import the aws_cloudwatch_log_group resources into terraform and retry the deploy.

1. cd terraform

2. terraform import aws_cloudwatch_log_group.indexer /aws/apigateway/azul-indexer-foo

3. terraform import aws_cloudwatch_log_group.service /aws/apigateway/azul-service-foo

4. cd ..

5. make deploy

If the error azul.RequirementError: The service account (SA) '...' is not authorized to access ... or that resource does not exist. Make sure that it exists, that the SA is registered with SAM and has been granted read access to the resource is encountered, ask an administrator of the Terra group azul-dev to add the service account as specified in the error messaged to that group. See 2.3.4 Google Cloud, TDR, and SAM for details.

After a successful invocation of make deploy, if the deployment is unresponsive and CloudWatch shows logs entries in the /aws/apigateway/… log group but not in /aws/lambda/…, first confirm whether the issue is the known KMSAccessDeniedException error. In the AWS Console, go to the Lambda function details page, click on the Test tab, and click on the Test buttton.

Note that it is normal for some Lambda functions to fail the test due to the parameters of the test event. Examine the error message to determine if the failure is due to a KMSAccessDeniedException which would be explicitly specified.

To resolve a KMSAccessDeniedException run the reset_lambda_role.py script to reset all the Lambda functions in the selected deployment.

3.7 Reindexing

The DSS instance used by a deployment is likely to contain existing bundles. To index them run:

make reindex

When reindexing, artificial notifications are generated by Azul.

The reindex make target will purchase a BigQuery slot commitment if:

1. No slot commitment is currently active, and
2. At least one catalog being indexed uses the TDR repository plugin.

To avoid cost-ineffective slot purchases, the reindex_no_slots target should be used instead of reindex if the reindexing is expected to complete in 15 minutes or less.

3.8 Cancelling an ongoing (re)indexing operation

python scripts/manage_queues.py purge_all

After that it is advisable to delete the indices and reindex at some later time.

3.9 Deleting all indices

To delete all Elasticsearch indices run

make delete

The indices can be created again using

make create

but they will be empty.

3.10 Deleting a deployment

1. cd to the project root, then

   source environment

2. Select the deployment to deleted

   _select foo.local

3. Delete all Elasticsearch indices in the selected deployment

   make delete

4. Delete the API Gateway base path mappings

   cd terraform
   make init
   terraform destroy $(terraform state list | grep aws_api_gateway_base_path_mapping | sed 's/^/-target /')
   cd ..

5. Destroy cloud infrastructure

   make -C terraform destroy

   The destruction of aws_acm_certificate resources may time out. Simply repeat this step until it succeeds.

6. From the shared bucket (run python -c 'from azul.deployment import aws; print(aws.shared_bucket)' to reveal its name), delete all keys relating to your deployment.

7. Delete the local Terraform state file at deployments/.active/.terraform.{$AWS_PROFILE}/terraform.tfstate.

4. Running indexer or service locally

While this method does run the service or indexer locally on your machine, it still requires that the cloud resources used by them are already deployed. See sections 2 and 3 on how to do that.

1. As usual, activate the virtual environment and source environment if you haven't done so already

2. cd lambdas/service

3. Run

   make local

4. You can now hit the app under http://127.0.0.1:8000/

PyCharm recently added a feature that allows you to attach a debugger: From the main menu choose Run, Attach to local process and select the chalice process.

5. Troubleshooting

Error: Invalid index during make deploy

aws_route53_record.service_0: Refreshing state... [id=XXXXXXXXXXXXX_service.dev.singlecell.gi.ucsc.edu_A]
 Error: Invalid index
   on modules.tf.json line 8, in module.chalice_indexer.es_endpoint:
    8:                 "${aws_elasticsearch_domain.index.endpoint}",
     |----------------
     | aws_elasticsearch_domain.index is empty tuple
 The given key does not identify an element in this collection value.

This may be an issue with Terraform. To work around this, run …

terraform state rm aws_elasticsearch_domain.index

… to update the Terraform state so that it reflects the deletion of the Elasticsearch domain. Now running make deploy should succeed.

NoCredentialProviders while running make deploy

If you get …

Failed to save state: failed to upload state: NoCredentialProviders: no valid providers in chain.
…
The error shown above has prevented Terraform from writing the updated state
to the configured backend. To allow for recovery, the state has been written
to the file "errored.tfstate" in the current working directory.

Running "terraform apply" again at this point will create a forked state,
making it harder to recover.

… during make deploy, your temporary STS credentials might have expired while terraform apply was running. To fix, run …

_login
(cd terraform && terraform state push errored.tfstate)

… to refresh the credentials and upload the most recent Terraform state to the configuration bucket.

AccessDeniedException in indexer lambda

If you get the following exception:

An error occurred (AccessDeniedException) when calling the GetParameter operation: User: arn:aws:sts::{account_id}:assumed-role/azul-indexer-{deployment_stage}/azul-indexer-{deployment_stage}-index is not authorized to perform: ssm:GetParameter on resource: arn:aws:ssm:{aws_region}:{account_id}:parameter/dcp/dss/{deployment_stage}/environment: ClientError
Traceback (most recent call last):
    ...
botocore.exceptions.ClientError: An error occurred (AccessDeniedException) when calling the GetParameter operation: User: arn:aws:sts::{account_id}:assumed-role/azul-indexer-{deployment_stage}/azul-indexer-{deployment_stage}-index is not authorized to perform: ssm:GetParameter on resource: arn:aws:ssm:{aws_region}:{account_id}:parameter/dcp/dss/integration/environment

Check whether the DSS switched buckets. If so, the lambda policy may need to be updated to reflect that change. To fix this, redeploy the lambdas (make package) in the affected deployment.

make requirements_update does not update transitive requirements

In some cases, make requirements_update might not produce any updates to transitive requirements, even if you expect them. For example, a sandbox build on Gitlab might identify updated transitive requirements even though doing make requirements_update locally doesn't.

This is a side effect of the Docker build cache on two different machines diverging to reflect different states on PyPI. This can be fixed by incrementing azul_image_version in the Dockerfile.

Unable to re-register service account with SAM

If you have destroyed your deployment and are rebuilding it, it's possible that SAM will not allow the Google service account to be registered again because the service account's email is the same in the current and previous incarnation of the deployment, while the service account's uniqueID is different. SAM does not support this.

A warning message stating that SAM does not allow re-registration of service account emails will be visible during the make sam step of the deployment process. To get around this, increment the current value of AZUL_DEPLOYMENT_INCARNATION in the deployment's environment.py file, then redeploy.

Unexpected warnings cause tests to fail in tearDownClass

Unexpected warnings that occur during testing will cause failures in AzulTestCase.tearDownClass. There is a context manager in AzulTestCase that keeps record of emitted warnings during test execution. Due to the unit test discovery process loading modules as it traverses directories, it’s possible that a warning is emitted outside the scope of the context manager.

In the two commands below, the unit test discovery process occurs within a different directory.

$ (cd test && python -m unittest service.test_app_logging.TestServiceAppLogging)

In the first case, it's possible that an unpermitted warning is emitted outside the AzulTestCase context manager, due to modules being loaded recursively from the directory test/. If a warning is emitted outside the context manager no test failure will occur.

$ (cd test/service && python -m unittest test_app_logging.TestServiceAppLogging)

In the second case, the test discovery process loads fewer modules due to the
narrowed working directory. This may emit a warning during test execution, enabling the context manager to catch the unpermitted warning, and fail appropriately.

Similarly, when running tests in PyCharm, its own proprietary test discovery process may also increase the chance of the AzulTestCase context manager causing a failure.

If these failures occur, add the warning to the list of permitted warnings found in AzulTestCase and commit the modifications.

Setting up the Azul build prerequisites on macOS 12 (Monterey)

The steps below are examplary for Python 3.11.6. Replace 3.11.6 with the value of azul_python_version in environment.py.

Make bash the default shell. Google it.

Install Homebrew. Google it.

Install pyenv:

brew install zlib pyenv

Install python

pyenv install 3.11.6

Set PYENV_VERSION to 3.11.6 in environment.local.py at the project root. Do not set SYSTEM_VERSION_COMPAT. For a more maintainable configuration use os.environ['azul_python_version'] as the value and import os at the top.

Install Docker Desktop. Google it.

Install Terraform by downloading and unziping the binary to a directory on the PATH. Be sure to download the file for the architecture of your Mac. For Apple Silicon the file name contains arm64, for older Intel Macs it's amd64.

Installing Python 3.8.12 on macOS 11 (Big Sur)

pyenv macOS 11 GitHub issue

Users of macOS 11 or later may encounter a build failed error when installing Python through pyenv. A patch was made available to remedy this:

First, ensure that bzip2 and any other requirements for the Python build environment are met. See pyenv wiki for details:

brew install openssl readline sqlite3 xz zlib bzip2

Follow any additional steps that brew prompts for at the end of the installation. These should include modifying path variables LDFLAGS and CPPFLAGS. The commands from the brew output to modify the aforementioned path variables can be placed in ~/.bash_profile to make the change persistent.

Then install Python 3.8.12 using pyenv by running:

pyenv install 3.8.12

Users of macOS 11 or later may encounter pip installation errors due to pip not being able to locate the appropriate wheels. The information below will help remedy this:

Resolution source

macOS 11 Release Notes

pip will not be able to locate the appropriate wheels due to the major release version of macOS being incremented from 10.x to 11.x, instead pip will attempt to compile wheels manually for wheels that it cannot locate.

In order to be able to run make requirements successfully, a backwards compatibility flag needs to be added to the environment.local.py file in the project root. The flag is SYSTEM_VERSION_COMPAT=1 and it needs to be inserted into the file (starting from line 25) as a key/value pair: 'SYSTEM_VERSION_COMPAT': 1.

6. Branch flow & development process

This section should be considered a draft. It describes a future extension to the current branching flow.

The section below describes the flow we want to get to eventually, not the one we are currently using while this repository recovers from the aftermath of its inception.

The declared goal here is a process that prevents diverging forks yet allows each project to operate independently as far as release schedule, deployment cadence, project management and issue tracking is concerned. The main challenges are 1) preventing contention on a single develop or master branch, 2) isolating project-specific changes from generic ones, 3) maintaining a reasonably linear and clean history and 4) ensuring code reuse.

The original repository, also known as upstream, should only contain generic functionality and infrastructure code. Project-specific functionality should be maintained in separate project-specific forks of that repository. The upstream repository will only contain a master branch and the occasional PR branch.

Azul dynamically imports project-specific plugin modules from a special location in the Python package hierarchy: azul.projects. The package structure in upstream is

root
├── ...
├── src
│   └── azul
│       ├── index
│       │   └── ...
│       ├── projects (empty)
│       ├── service
│       │   └── ...
│       └── util
│       │   └── ...
└── ...

Note that the projects directory is empty.

The directory structure in forked repositories is generally the same with one important difference. While a fork's master branch is an approximate mirror of upstream's master and therefore also lacks content in projects, that directory does contain modules in the fork's develop branch. In HumanCellAtlas/azul-hca, the fork of Azul for the HumanCellAtlas project, the develop branch would look like this:

root
├── ...
├── src
│   └── azul
│       ├── index
│       │   └── ...
│       ├── projects
│       │   └── hca
│       │       └── ...
│       ├── service
│       │   └── ...
│       └── util
│       │   └── ...
└── ...

The develop branch would only contain changes to the azul.projects.hca package. All other changes would have to be considered generic—they would occur on the fork's master branch and eventually be merged into upstream's master branch. The master branches in each fork should not be divergent for sustained periods of time while the project-specific branches can and will be.

The reason why each fork maintains a copy of the master branch is that forks generally need to have a place to test and evaluate generic features before they are promoted upstream. If there wasn't a master branch in a fork, the project-specific develop branch in that fork would inevitably conflate project-specific changes with generic ones. It would be very hard to selectively promote generic changes upstream, even if the generic changes were separate commits.

The flow presented here establishes an easy-to-follow rule: If you're modifying azul.projects.hca, you need to do so in a PR against develop. If you're modifying anything else, you need to do so in a PR against master. The figure below illustrates that.

                                                      ●────● feature/generic-foo
                                                     ╱
                                              4     ╱
    ─────●────────────────────────────────────●────●──────────────        master
          ╲                                  ╱
 azul      ╲                                ╱
 ─ ─ ─ ─ ─ ─╲─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ╱ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─
 azul-hca    ╲                            ╱
              ╲                          ╱
    ──────●────●────●────●────●────●────●──────────────────────────       master
           ╲   1     ╲    ╲   A'   B'
            ╲         ╲    ╲
             ╲         ╲    ●────● feature/master/generic-stuff
              ╲         ╲   A    B
               ╲         ╲
                ●─────────●─────────────●────●────●─────────────────     develop
                2         3              ╲   C'   D'
                                          ╲
                                           ●────● feature/develop/specific-stuff
                                                C    D

Merge commit 1 from the upstream master branch integrates upstream changes into the fork. These may be generic changes merged upstream from other forks or changes that were directly PR-ed against master in upstream. Commit 2 marks the beginning of the develop branch, adding the azul.projects.hca package. Merge commit 3 brings the changes from commit 1 into the develop branch.

Another important rule is that collaborative branches like develop and master are never rebased. Changes are exchanged between them using merge commits instead. Individual branches however, like feature branches, are always rebased onto the base branch. In the above example, feature/master/generic-stuff is first rebased onto master, creating commits A' and B'. Later those changes are merged upstream via commit 4. Both the rebase and the merge happen via a pull request, but the landing action will be "Rebase and merge" for the first PR and "Create a merge commit" for the second.

The reason for this distinction is that rebasing usually triggers more rebasing of branches that were based on the rebased branch. It also rewrites the commit timestamps, thereby obfuscating the history to some extent. For these two reasons, rebasing is not a sustainable practice for collaborative branches. For individual branches however, rebasing is possible because feature branches are typically not used as a base for other branches. Rebasing is also desirable because it produces a cleaner, linear history and we should use it whenever possible. The back and forth merging between collaborative branches produces a history that's somewhat convoluted so it is important to keep the history as clean as possible in between merges.

Generic changes don't have to be conceived in a fork. We can also PR them directly against the upstream repository as illustrated by branch feature/generic-foo.

The most common type of pull request in a fork is one against that fork's develop branch, feature/develop/specific-stuff for example. Note that changes occurring on develop are never merged upstream.

As mentioned before, merge commit 4 is done via a pull request against the upstream repository. It is possible and perfectly acceptable that such upstream PRs combine multiple unrelated changes. They should be requested by the team lead for the forking project and reviewed by an upstream lead. Shortly after the PR lands, the requesting lead should perform a fast-forward merge of the upstream master branch into the fork's master branch. This will propagate the merge commit downstream before any subsequent commits occurring on fork's master have a chance to complicate the history by introducing the infamous merge of merge commits.

$ git branch
* master
  develop
$ git merge --ff-only upstream/master
Updating 450b0c0..212003c
Fast-forward

This procedure requires that the lead's local clone of the fork be set up with two remotes: origin (the forked repository) and upstream (the upstream repository). Other team members can usually get by with just one remote, origin.

6.1 Deployment branches

The code in the upstream repository should never be deployed anywhere because it does not contain any concrete modules to be loaded at runtime. The code in a fork, however, is typically active in a number of deployments. The specifics should be left to each project but the rule of thumb should be that each deployment corresponds to a separate branch in the fork. The azul-hca fork has four deployments: development, integration, staging and production. The development deployment, or dev, is done from the develop branch. Whenever a commit is pushed to that branch, a continuous deployment script deploys the code to AWS. The other deployment branches are named accordingly. Changes are promoted between deployments via a merge. The merge is likely going to be a fast-forward. A push to any of the deployment branches will trigger a CI/CD build that performs the deployment. The promotion could be automatic and/or gated on a condition, like tests passing.

7. Operational Procedures

7.1 Main deployments and promotions

We will refer to the branch of the stage to which you are deploying as the TARGET branch. The branch of the stage just below will be referred to as the SOURCE branch.

This cheat sheet may differ from branch to branch. Be sure to follow the cheat sheet in the README on the branch currently checked out.

7.1.1 Initial setup

Note: You can skip this step if you've deployed or promoted with Gitlab at least once already.

1. For promotion, we recommend keeping a separate clone of Azul that is never in a dirty state. To create this if it doesn't yet exist run

   git clone git@github.com:DataBiosphere/azul.git azul.stable

   Then follow the setup instructions in 2.3 Project configuration.

2. Next you will need to login to our Gitlab instance in order to be able to push to Gitlab which automatically takes care of most of the deployment process. If you haven't signed on yet, sign on with Github. You will need at least developer permissions in order to be able to push to Gitlab. Contact the team lead if you have problems signing on or have insufficient permissions.

3. Deposit you public SSH key into the SSH keys section of your profile so that you can push to Git repositories hosted on that Gitlab instance.

4. Now that your SSH key is set up, you will need to add Gitlab as a remote. Run

   git remote add gitlab.dev git@ssh.gitlab.dev.singlecell.gi.ucsc.edu:ucsc/azul.git

   Run

   git fetch gitlab.dev

   to ensure that your connection is working.

If you have been given write access to our production Gitlab instance, you need to repeat these steps for that instance as well. For the name of the git remote use gitlab.prod instead of gitlab.dev in step 4 above. The hostname of that instance is the same as that of the Gitlab instance for the lesser deployments, without .dev.

Note that access to the production instance of Gitlab does not necessarily imply access to production AWS account which that Gitlab instance deploys to. So while you may be able to run certain make targets like make reindex or make deploy against the development AWS account (with dev, integration or staging selected), you may not be able to do the same for the production AWS account (with prod selected).

7.1.2 Prepare for promotion

NOTE: Skip these steps if you are deploying without promoting changes.

NOTE: If promoting to staging or prod you will need to do these steps at least 24 hours in advance so that the release notes are ready in time.

1. From the azul.stable clone make sure all of the relevant branches are up to date

   cd azul.stable
   git checkout SOURCE
   git pull
   git checkout TARGET
   git pull

2. You should be on the TARGET branch. Run

   git merge --no-ff SOURCE

   and resolve conflicts in necessary. Conflict resolution should only be necessary if cherry-picks occurred on the target branch.

3. The merge may have affected README.md, the file you are looking at right now. Reopen the file now to ensure you are following the updated version.

4. Now you need to create the release notes. (Skip this step if no link to the release notes document can be found either in the #dcp-ops channel on HCA Slack or in the Google Drive folder mentioned in the DCP release SOP.

   To produce the list of changes for the DCP release notes, first find the previous release tag for the TARGET branch. Then run:

   git log LAST_RELEASE_TAG..HEAD --format="%C(auto) %h %s" --graph

   Edit this output so that the commits within merged branches are removed, along with merge commits between deployments. For example

   *  C  <-- merge commit
   |\
   | *  B
   |/
   *  A
   *  Merge branch 'develop' into integration

   should be changed to look like

   *  C  <-- merge commit
   *  A

   For the version, use the full hash of the latest commit:

   git log -1 --format="%H"

5. At this point you should determine whether or not you will need to reindex. The CHANGELOG.yml should contain this information but is notoriously unreliable. Try running

   git diff LAST_RELEASE_TAG..HEAD src/azul/project/ src/azul/indexer.py src/azul/plugin.py src/azul/transformer.py

   where LAST_RELEASE_TAG is the previous release of the target branch. If the diff contains non-trivial changes reindexing is probably necessary. When in doubt assume yes.

7.1.3 Finishing up deployment / promotion

If promoting to staging or production this part of the process must be coordinated on the #dcp-ops Slack channel. While any component can technically promote to integration at any time, you should consider that promoting to integration while the DCP-wide test is red for that deployment could interfere with other teams' efforts to fix the test. If in doubt ask on #dcp-ops.

None of these steps can be performed ahead of time. Only perform them once you are ready to actually deploy.

1. Activate your virtual environment and run

   source environment

   and then select the target deployment stage with

   _select STAGE

   where stage is one of dev, integration, staging, or prod

2. Now you need to push the current branch to Github. This is needed because the Gitlab build performs a status check update on Github. This would fail if Github didn't know the commit.

   git push origin

3. Finally, push to Gitlab.

   git push gitlab.dev   # for a dev, integration or staging deployment
   git push gitlab.prod  # for a prod deployment

   The build should start immediately. You can monitor its progress from the Gitlab Pipelines page.

   If reindexing and promoting to staging or production, send a second warning about reindexing to the #data-wrangling channel at this point.

   Wait until the pipeline on Gitlab succeeds or fails. If the build fails before the deploy stage, no permanent changes were made to the deployment but you need to investigate the failure. If the pipeline fails at or after the deploy stage, you need triage the failure. If it can't be resolved manually, you need to reset the branch back to the LAST_RELEASE_TAG and repeat step 2 in this section.

4. Invoke the health and version endpoints.

   • For the develop branch and the corresponding dev deployment use

     http https://indexer.dev.singlecell.gi.ucsc.edu/version
     http https://service.dev.singlecell.gi.ucsc.edu/version
     http https://indexer.dev.singlecell.gi.ucsc.edu/health
     http https://service.dev.singlecell.gi.ucsc.edu/health

   • For the integration branch/deployment use

     http https://indexer.integration.singlecell.gi.ucsc.edu/version
     http https://service.integration.singlecell.gi.ucsc.edu/version
     http https://indexer.integration.singlecell.gi.ucsc.edu/health
     http https://service.integration.singlecell.gi.ucsc.edu/health

   • For the staging branch/deployment use

     http https://indexer.staging.singlecell.gi.ucsc.edu/version
     http https://service.staging.singlecell.gi.ucsc.edu/version
     http https://indexer.staging.singlecell.gi.ucsc.edu/health
     http https://service.staging.singlecell.gi.ucsc.edu/health

   • For the prod branch/deployment use

     http https://indexer.singlecell.gi.ucsc.edu/version
     http https://service.singlecell.gi.ucsc.edu/version
     http https://indexer.singlecell.gi.ucsc.edu/health
     http https://service.singlecell.gi.ucsc.edu/health

5. Assuming everything is successful, run

   make tag

   and the

   git push ...

   invocation that it echoes.

6. In Zenhub, move all tickets from the pipeline representing the source deployment of the promotion to the pipeline representing the target deployment.

7. In the case that you need to reindex run the manual reindex job on the Gitlab pipeline representing the most recent build on the current branch.

7.2 Big red button

In the event of an emergency, Azul can be shut down immediately using the enable_lambdas.py script. Before using this script, make sure that the desired deployment is selected and your Python virtual environment is activated.

Shut down Azul by running

python scripts/enable_lambdas.py --disable

Once your issue has been resolved, you can resume Azul's services by running

python scripts/enable_lambdas.py --enable

7.3 Copying bundles

In order to copy bundles from one DSS instance to another, you can use scripts/copy_bundles.py. The script copies specific bundles or all bundles listed in a given manifest. It iterates over all source bundles, and all files in each source bundle. It copies the files by determining the native URL (s3://… ) of the DSS blob object for each file and passing that native URL to the destination DSS' PUT /files endpoint as the source URL parameter for that request. This means that it is actually the destination DSS that physically copies the files. Once all files in a bundle were copied, the script requests the PUT /bundles endpoint to create a copy of the source bundle.

The script is idempotent, meaning you can run it repeatedly without harm, mostly thanks to the fact that the DSS' PUT /files and PUT /bundles endpoints are idempotent. If a script invocation resulted in a transient error, running the script again will retry all DSS requests, both successful requests and requests that failed in the previous invocation.

In order to determine the native URL of the source blob, the script needs direct read access to the source DSS bucket. This is because blobs are an implementation detail of the DSS and obtaining their native URL is not supported by the DSS.

Furthermore, The destination DSS requires the source object to carry tags containing the four checksums of the blob. Some blobs in some DSS instances have those tags, some don't. It is unclear the tags are supposed to be present on all blob objects or if their presence is incidental. To work around this, the script can optionally create those tags when the destination DSS complains that they are missing. To enable the creation of checksum tags on source blob objects, use the ---fix-tags option. Please be aware that --fix-tags entails modifying object tags in the source (!) bucket.

The destination DSS instance requires read access to the blobs in the source DSS bucket. The integration and staging instances can read each other's buckets so copies can be made between those two instances. To copy bundles from a DSS instance that is in a different AWS account compared to the destination instance, from prod to integration, for example, you will likely need to modify the source DSS bucket's bucket policy.

You should never copy to the HCA prod instance of the DSS.

Here is a complete example for copying bundles from prod to integration.

1) Ask someone with admin access to the DSS prod bucket (org-hca-dss-prod) to add the following statements to the bucket policy of said bucket. The first statement gives the destination DSS read access to the source DSS instance. The second statement gives you read access to that bucket (needed for direct access) and permission to set tags on objects (needed for --fix-tags).

   [
       {
           "Sid": "copy-bundles",
           "Effect": "Allow",
           "Principal": {
               "AWS": [
                   "arn:aws:iam::861229788715:role/dss-integration",
                   "arn:aws:iam::861229788715:role/dss-s3-copy-sfn-integration",
                   "arn:aws:iam::861229788715:role/dss-s3-copy-write-metadata-sfn-integration"
               ]
           },
           "Action": [
               "s3:GetObject",
               "s3:GetObjectTagging"
           ],
           "Resource": "arn:aws:s3:::org-hca-dss-prod/*"
       },
       {
           "Sid": "direct-read-access-and-retag-blobs",
           "Effect": "Allow",
           "Principal": {
               "AWS": [
                   "arn:aws:iam::861229788715:role/dcp-admin",
                   "arn:aws:iam::861229788715:role/dcp-developer"
               ]
           },
           "Action": [
               "s3:GetObject",
               "s3:GetObjectTagging",
               "s3:PutObjectTagging"
           ],
           "Resource": [
               "arn:aws:s3:::org-hca-dss-prod/*"
           ]
       }
   ]

2) Select the integration deployment:

   _select integration

3) Run

   python scripts/copy_bundles.py --map-version 1.374856 \
                                  --fix-tags \
                                  --source https://dss.data.humancellatlas.org/v1 \
                                  --destination https://dss.integration.data.humancellatlas.org/v1 \
                                  --manifest /path/to/manifest.tsv

The --map-version option adds a specific duration to the version of each copied file and bundle. Run python scripts/copy_bundles --help for details.

8. Scale testing

Scale testing can be done with Locust. Locust is a development requirement so running it is straight-forward with your development environment set up.

1. Make sure Locust is installed by running

   locust --version

   If it is not installed, do step 1.3 in this README.

2. To scale test the Azul web service on integration run

   locust -f scripts/locust/service.py

   If you want to test against a different stage use the --host option:

   locust -f scripts/locust/service.py --host https://service.dev.singlecell.gi.ucsc.edu

3. Navigate to http://localhost:8090 in your browser to start a test run.

For more advanced usage refer to the official Locust documentation.

9. Continuous deployment and integration

For the purposes of continually testing and deploying the Azul application, we run the community edition of GitLab on a project-specific EC2 instance. There is currently one such instance for the sandbox and dev deployments and another one for prod.

The GitLab instances are provisioned through the gitlab Terraform component. For more information about Terraform components, refer the section on shared resources managed by Terraform. Within the gitlab component, the dev.gitlab child component provides a single Gitlab EC2 instance that serves our CI/CD needs not only for dev but for integration and staging as well. The prod.gitlab child component provides the Gitlab EC2 instance for prod.

To access the web UI of the Gitlab instance for dev, visit https://gitlab.dev.explore.…/, authenticating yourself with your GitHub account. After attempting to log in for the first time, one of the administrators will need to approve your access. For prod use https://gitlab.explore.…/.

To have the Gitlab instance build a branch, one pushes that branch to the Azul fork hosted on the Gitlab instance. The URL of the fork can be viewed by visiting the GitLab web UI. One can only push via SSH, using a public SSH key that must be deposited in each user's profile on the GitLab web UI.

An Azul build on Gitlab runs the test, package, deploy, and integration_test Makefile targets, in that order. The target deployment for feature branches is sandbox, the protected branches (develop and prod use their respective deployments.

9.1 VPN access to GitLab

The GitLab EC2 instance resides in a VPC that can only be accessed through a VPN. The VPN uses AWS Client VPN. It is Amazon's flavor of OpenVPN. The AWS Client VPN endpoint is set up by Terraform as part of the dev.gitlab and prod.gitlab components. VPN clients authenticate via certificates signed by a certificate authority (CA) that is self-signed. A system administrator (currently the technical lead) manages the CA on their local disk. That is the only place where the private key for signing the CA certificate is kept. If the CA private key is lost, the CA must be reinitialized, the VPN must be redeployed and new client certificates must be issued. Each deployment of GitLab uses a separate CA and therefore a separate set of client certificates.

Each client certificate is backed by a private key as well. That private key resides solely on the developer's local disk. If the developer's private key is lost, a new one must be issued.

When a developer with VPN access departs the team, either the entire CA must be reinitialized and all remaining client certificates reissued or the departing developer's certificates must be revoked by adding it to the list of revoked client certificates on the AWS Client VPN instance. The VPN's server's certificate and private key is stored in ACM so that AWS Client VPN can authenticate itself to clients and check validity of the certificates that clients present to the server. Both client and server keys must be signed by the same CA.

9.1.1 Setting up a VPN client

Install an OpenVPN client. On Ubuntu, the respective package is called network-manager-openvpn-gnome. Popular clients for macOS are Tunnelblick (free) and Viscosity (for pay, with 30 day trial). For Windows, only Viscosity was tested but the official Windows client may also work there.

Generate a certificate request, import the certificate and generate the .ovpn file containing the configuration for the VPN connection:

_select dev.gitlab  # or prod.gitlab, anvildev.gitlab
cd terraform/gitlab/vpn
git submodule update --init easy-rsa
make init  # (do this only once per GitLab deployment)
make request  # then send request to administrator
make import  # paste the certificate
make config > ~/azul-gitlab-dev.ovpn  # or azul-gitlab-prod.ovpn

The make init step creates a PKI directory in ~/.local/share outside of the Azul source tree. It should only be done once per GitLab deployment. On a second attempt it will ask for confirmation to overwrite the existing directory. If confirmed, existing OpenVPN client connections will remain functional (as they keep a copy of the private key) but you will lose the ability to regenerate the .ovpn file.

Now import the generated .ovpn file into your client. make config prints instructions on how to do so on Ubuntu. For other VPN clients the process is pretty much self-explanatory. Delete the file after importing it. It contains the private key and can always be regenerated again later using make config.

9.1.2 Ensuring split tunnel on client

Except on stable deployments, you should configure the client to only route VPC traffic through the VPN. The VPN server will not forward any other traffic, in what's commonly referred to as a split tunnel. The key indicator of a split tunnel is that it doesn't set up a default route on the client system. There will only be a route to the private 172.… subnet of the GitLab VPC but the default route remains in place.

On stable deployments, split tunnels are prohibited.

The make config step prints instruction on how to configure a split tunnel on Ubuntu.

For Viscosity, the steps are as follows:

1) Click the Viscosity menu bar icon (or the task bar icon on windows)

2) Click Preferences

3) Right-click azul-gitlab-dev or azul-gitlab-prod -> click Edit

4) Click the Networking tab

5) Under All traffic, select Automatic (Set by server)

6) Click Save

For Tunnelblick, the steps are as follows:

1) Right-click the Tunnelblick menu bar icon

2) Click VPN Details …

3) Click on the left-hand side bar entry for the connection you just imported

4) On the Settings tab of the right-hand side of the window, make sure that the Route all IPv4 traffic through the VPN option is unchecked

9.1.2 Setting up the certificate authority

This must be done by a system administrator before a GitLab instance is first deployed:

_select dev.gitlab  # or prod.gitlab
cd terraform/gitlab/vpn
git submodule update --init easy-rsa
make ca  # initialize the CA (do this only once)
make server  # build the server certificate
make publish  # upload the server certificate to ACM
cd ..
make apply  # (re)deploy GitLab

9.1.3 Issuing a certificate

To issue a client certificate for a developer so that they can access the VPN, ask the developer to send you a certificate request as described in the previous section . The request must be made under the developer's email address as the common name (CN). Sign the request:

_select dev.gitlab  # or prod.gitlab
cd terraform/gitlab/vpn
git submodule update --init easy-rsa
make import/joe@foo.org
make sign/joe@foo.org

Send the resulting certificate back to the requesting developer.

The communication channel through which requests and certificates are messaged does not need to be private but it needs to ensure the integrity of the messages.

9.1.4 Revoking a certificate

_select dev.gitlab  # or prod.gitlab
cd terraform/gitlab/vpn
git submodule update --init easy-rsa
make revoke/joe@foo.org
make publish_revocations

To list all previously issued certificates, use make list.

There are now precautions in place to prevent this situation but I'll mention it anyways. If this list contains more than one active certificate for the same CN, all but the most recent one needs to be revoked by serial. Since easyrsa does not support this out of the box, we need to jump through some extra hoops:

eval "`make _admin _env`"
mv $EASYRSA_PKI/issued/joe@foo.org.crt $EASYRSA_PKI/issued/joe@foo.org.crt.orig
cp $EASYRSA_PKI/certs_by_serial/<SERIAL_OF_CERT_TO_BE_REVOKED>.pem $EASYRSA_PKI/issued/joe@foo.org.crt
make revoke/joe@foo.org
make publish_revocations
mv $EASYRSA_PKI/issued/joe@foo.org.crt.orig $EASYRSA_PKI/issued/joe@foo.org.crt

9.1.5 Issuing a certificate on a person's behalf

A private key and OpenVPN configuration can be generated by a system administrator on behalf of any person that doesn't have a configured working copy of this repository. Doing so has the disadvantage of making that person's private key known to the system administrator and anyone that eavesdrops on the channel through which the OpenVPN configuration (which includes the private key) is communicated to the person.

To generate the key and OpenVPN configuration file on another person's behalf, invoke the make steps as outlined in 9.1.1 and 9.1.3 but use make client_cn=joe@foo.org instead of make.

9.2 The Sandbox Deployment

There is only one such deployment and it should be used to validate feature branches (one at a time) or to run experiments. This implies that access to the sandbox must be coordinated externally e.g., via Slack. The project lead owns the sandbox deployment and coordinates access to it.

9.3 Security

Gitlab has AWS write permissions for the AWS services used by Azul and the principle of least privilege is applied as much as IAM allows it. Some AWS services support restricting the creation and deletion of resource by matching on the name. For these services, Gitlab can only create, modify or write resources whose name begins with azul-*. Other services, such as API Gateway only support matching on resource IDs. This is unfortunate because API Gateway allocates the ID. Since it is therefore impossible to know the ID of an API before creating it, Gitlab must be given write access to all API IDs. For details refer to the azul-gitlab role and the policy of the same name, both defined in gitlab.tf.json.template.py.

Gitlab does not have general write permissions to IAM, its write access is limited to creating roles and attaching policies to them as long as the roles and policies specify the azul-gitlab policy as a permissions boundary. This means that code running on the Gitlab instance can never escalate privileges beyond the boundary. This mechanism is defined in the azul-gitlab-iam policy.

Code running on the Gitlab instance has access to credentials of a Google Cloud service account that has write privileges to Google Cloud. This service account for Gitlab is created automatically by TF but its private key is not. They need to created manually and copied to /mnt/gitlab/runner/config/etc on the instance. See section 9.9 for details.

9.4 Networking

The networking details are documented in gitlab.tf.json.template.py. The Gitlab EC2 instance uses a VPC and is fronted by an Application Load Balancer (ALB) and a Network Load Balancer (NLB). The ALB proxies HTTPS access to the Gitlab web UI, the NLB provides SSH shell access and git+ssh access for pushing to the project forks on the instance.

9.5 Storage

The Gitlab EC2 instance is attached to an EBS volume that contains all of Gitlab's data and configuration. That volume is not controlled by Terraform and must be created manually before terraforming the gitlab component for the first time. Details about creating and formatting the volume can be found in gitlab.tf.json.template.py. The volume is mounted at /mnt/gitlab. The configuration changes are tracked in a local Git repository on the system administrator's computer. The system administrator keeps the configuration files consistent between GitLab instances.

When an instance boots and finds the EBS volume empty, Gitlab will initialize it with default configuration. That configuration is very vulnerable because the first user to visit the instance will be given the opportunity to chose the root password. It is therefore important that you visit the Gitlab UI immediately after the instance boots for the first time on an empty EBS volume.

Other than that, the default configuration is functional but lacks features like sign-in with Github and a Docker image repository. To enable those you could follow the respective Gitlab documentation but a faster approach is to compare /mnt/gitlab/config/gitlab.rb between an existing Gitlab instance and the new one. Just keep in mind that the new instance might have a newer version of Gitlab which may have added new settings. You may see commented-out default settings in the new gitlab.rb file that may be missing in the old one.

9.5.1 Freeing up storage space

There are three docker daemons running on the instance: the RancherOS system daemon, the RancherOS user daemon and the Docker-in-Docker (DIND) daemon. For reasons unknown at this time, the DIND keeps caching images, continually consuming disk space until the /mnt/gitlab volume fills up. In the past, this occurred once every six months or so. One of the symptoms might be a failing unit test job with message like

2021-03-11 19:38:05,133 WARNING MainThread: There was a general error with document ContributionCoordinates(entity=EntityReference(entity_type='files', entity_id='5ceb5dc3-9194-494a-b1df-42bb75ab1a04'), aggregate=False, bundle=BundleFQID(uuid='94f2ba52-30c8-4de0-a78e-f95a3f8deb9c', version='2019-04-03T103426.471000Z'), deleted=False): {'_index': 'azul_v2_dev_test_files', '_type': 'doc', '_id': '5ceb5dc3-9194-494a-b1df-42bb75ab1a04_94f2ba52-30c8-4de0-a78e-f95a3f8deb9c_2019-04-03T103426.471000Z_exists', 'status': 403, 'error': {'type': 'cluster_block_exception', 'reason': 'blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];'}}. Total # of errors: 1, giving up.

A cron job running on the instance should prevent this by periodically pruning unused images. If the above error occurs despite that, there might be a problem with that cron job. To manually clean up unused images run:

sudo docker exec -it gitlab-dind docker image prune -a --filter "until=720h"

on the instance.

9.6 The Gitlab web application

The instance runs Gitlab CE running inside a rather elaborate concoction of Docker containers. See gitlab.tf.json.template.py for details. Administrative tasks within a container should be performed with docker exec. To reconfigure Gitlab, for example, one would run docker exec -it gitlab gitlab-ctl reconfigure.

9.7 Registering the Gitlab runner

The runner is the container that performs the builds. The instance is configured to automatically start that container. The primary configuration for the runner is in /mnt/gitlab/runner/config/config.toml. There is one catch, on a fresh EBS volume that just been initialized, this file is missing, so the container starts but doesn't advertise any runners to Gitlab.

The easiest way to create the file is to kill the gitlab-runner container and the run it manually using the docker run command from the systemd unit file, but adding -it after run and register at the end of the command. You will be prompted to supply a URL and a registration token as documented here.

Note that since version 15.0.0 of GitLab, there is no way to convert a runner from shared to project-specific or vice versa. If you want to register a runner reserved to a specific group, you must get the registration token from the CI/CD — Runners page of the respective group. Runners reserved to a project must be registered from the project's Settings — CI/CD — Runners page. Shared runners are registered via Admin — Overview — Runners.

Specify docker as the runner type and

docker.gitlab.anvil.gi.ucsc.edu/ucsc/azul/runner:latest

as the image for Azul runners. For generic runners you could use the docker:20.10.18-ce image instead, but you'd need to match the tag (aka version) of the image currently used for the gitlab-dind container.

Here's an example terminal transcript:

$ systemctl stop gitlab-runner.service

$ systemctl show gitlab-runner.service | grep ExecStart=
ExecStart={ path=/usr/bin/docker ; argv[]=/usr/bin/docker run --name gitlab-runner …

$ /usr/bin/docker run -it --name gitlab-runner --rm --volume /mnt/gitlab/runner/config:/etc/gitlab-runner --network gitlab-runner-net --env DOCKER_HOST=tcp://gitlab-dind:2375 gitlab/gitlab-runner:v15.9.1 register
Runtime platform                                    arch=amd64 os=linux pid=7 revision=d540b510 version=15.9.1
Running in system-mode.

Enter the GitLab instance URL (for example, https://gitlab.com/):
https://gitlab.anvil.gi.ucsc.edu/
Enter the registration token:
REDACTED
Enter a description for the runner:
[cd20ca0ec956]:
Enter tags for the runner (comma-separated):

Enter optional maintenance note for the runner:

WARNING: Support for registration tokens and runner parameters in the 'register' command has been deprecated in GitLab Runner 15.6 and will be replaced with support for authentication tokens. For more information, see https://gitlab.com/gitlab-org/gitlab/-/issues/380872
Registering runner... succeeded                     runner=GR1348941eDiqsoCC
Enter an executor: docker, shell, ssh, docker-ssh+machine, instance, custom, docker-ssh, parallels, virtualbox, docker+machine, kubernetes:
docker
Enter the default Docker image (for example, ruby:2.7):
docker.gitlab.anvil.gi.ucsc.edu/ucsc/ azul/runner:latest
Runner registered successfully. Feel free to start it, but if it's running already the config should be automatically reloaded!

Configuration (with the authentication token) was saved in "/etc/gitlab-runner/config.toml"

Once the container exits, config.toml should have been created. Edit it and adjust the volumes setting to read

volumes = ["/var/run/docker.sock:/var/run/docker.sock", "/cache", "/etc/gitlab-runner/etc:/etc/gitlab"]

If you already have a GitLab instance to copy config.toml from, do that and register the runners as described above. Copy the runner tokens from the newly added runners at the end of config.toml to the preexisting runners. Then discard the newly added runners from the file. For another instance's config.toml to work on a new instance, the only piece of information that needs to be updated is the runner token. That's because the runner token is derived from the registration token which is different between the two instances.

Finally, start the runner unit using systemctl start gitlab-runner.service or simply reboot the instance. Either way, the Gitlab UI should now show the newly registered runners.

9.8 The Gitlab runner image for Azul

Because the first stage of the Azul pipeline on Gitlab creates a dedicated image containing the dependencies of the subsequent stages, that first stage only requires the docker client binary, make and bash to be in the runner. These are provided by yet another custom Docker image for the Gitlab runner that executes Azul builds. This image must be created when the EBS volume attached to the Gitlab instance is first provisioned, or when the corresponding Dockerfile is modified. See terraform/gitlab/runner/Dockerfile for details on how to build the image and register it with the runner.

9.9 Updating Gitlab

Modify the Docker image tags in gitlab.tf.json.template.py and run make apply in terraform/gitlab. The instance will be terminated (the EBS volume will survive) and a new instance will be launched, with fresh containers from updated images. This should be done regularly.

9.10 The Gitlab Build Environment

The /mnt/gitlab/runner/config/etc directory on the Gitlab EC2 instance is mounted into the build container as /etc/gitlab. The Gitlab build for Azul copies the files from the azul subdirectory of that directory into the Azul project root. Secrets and other Gitlab-specific settings should be specified in /mnt/gitlab/runner/config/etc/azul/environment.local which will end up in ${project_root}/environment.local where source environment will find and load them. For secrets, we prefer this mechanism over specifying them as environment variables under project settings on the Gitlab web UI. Only people with push access can push code to intentionally or accidentally expose those variables, push access is tied to shell access which is what one would normally need to modify those files.

9.11. Cleaning up hung test containers

When cancelling the make test job on Gitlab, test containers will be left running. To clean those up, ssh into the instance as described in gitlab.tf.json.template.py and run docker exec gitlab-dind docker ps -qa | xargs docker exec gitlab-dind docker kill and again but with rm instead of kill.

10. Kibana and Cerebro

Kibana is a web UI for interactively querying and managing an Elasticsearch instance. To use Kibana with Azul's AWS Elasticsearch instance, you have two options:

• For one, you can add your local IP to the policy of Azul's AWS Elasticsearch instance and access its Kibana directly. This can take 10 minutes and you might have to do it repeatedly because the policy is reset periodically, potentially multiple times a day.

• Alternatively, you can use scripts/kibana_proxy.py to run Kibana locally and have it point at Azul's AWS Elasticsearch instance. The script also starts a signing proxy which eliminates the need to add your local IP to the Elasticsearch policy, using your local AWS credentials instead for authentication.

  For the script to work, you need to

  • have Docker installed,

  • a deployment selected, and

  • environment sourced.

Cerebro is a cluster management web UI for Elasticsearch. It is very useful for determining the status of individual nodes and shards. In addition to the Kibana container, scripts/kibana_proxy.py also starts one for Cerebro.

Look for this line in the script output:

Now open Kibana at http://127.0.0.1:5601/ and open Cerebro at
http://127.0.0.1:5602/#/overview?host=http://localhost:5603 (or paste in
http://localhost:5603)

and open the specified URLs in your browser.

10.1 Connecting Kibana to a local Elasticsearch instance

Certain unit tests use a locally running Elasticsearch container. It's possible to connect a Kibana instance to such a container, in order to aid debugging.

While the unit test is running (paused at a breakpoint), open a terminal window.

Download the Kibana container:

kibana_image=$azul_docker_registry$(python -m azul 'docker.resolve_docker_image_for_launch("pycharm")')
docker pull $kibana_image

Copy the container name for the Elasticsearch instance you want to examine. This is likely the most recent entry in

docker ps

Run

docker run --link ES_CONTAINER_NAME:elasticsearch -p 5601:5601 $kibana_image

where ES_CONTAINER_NAME is what you copied from above.

Kibana should now be available at http://0.0.0.0:5601.

Some of these steps were taken or modified from the official Elasticsearch documentation.

11. Managing dependencies

We pin all dependencies, direct and transitive ones alike. That's the only way to get a somewhat reproducible build. It's possible that the build still fails if a dependency version is deleted from pypi.org or if a dependency maintainer re-releases a version, but aside from caching all dependencies, pinning them is next best thing for reproducibility of the build.

Now, while pinning direct dependencies should be routine, chasing down transitive dependencies and pinning those is difficult, tedious and prone to errors. That's why we automate that step: When a developer updates, adds or removes a direct dependency, running make requirements_update will reevaluate all transitive dependencies and update their pins. If the added direct dependency has transitive dependencies, those will be picked up. It's likely that the reevaluation picks up updates to transitive dependencies unrelated to the modified direct dependency, but that's unavoidable. It's even possible that a direct dependency update causes a downgrade of a transitive dependency if the updated direct dependency further restricts the allowed version range of the transitive dependency.

We distinguish between run-time and build-time — or development — dependencies. A run-time dependency is a one that is needed by deployed code. A build-time dependency is one that is not needed by deployed code, but by some other code, like unit tests, for example. A developer's virtualenv will have both run-time and build-time dependencies installed. Combined with the distinction between direct and transitive dependencies this yields four categories of dependencies. Let's refer to them as DR (direct run-time), TR (transitive run-time), DB (direct build-time) and TB (transitive build-time). The intersections DR ∩ TR, DB ∩ TB, DR ∩ DB, TR ∩ TB and DR ∩ TB should all be empty but the intersection TR ∩ DB may not be.

Ambiguities can arise as to which version of a requirement should be used when multiple requirements have overlapping transitive dependencies. We can't resolve these ambiguities automatically because different versions of a package may have different dependencies in and of themselves, so pinning just the dependency in question might omit some of its dependencies. By pinning it explicitly the normal dependency resolution kicks in, including all transitive dependencies of the pinned version.

make requirements_update will raise an exception when ambiguous requirements are found.

ERROR   MainThread: Ambiguous version of transitive runtime requirement jsonschema==2.6.0,==3.2.0. Consider pinning it to the version used at build time (==3.2.0).

With this example case the solution would be to add jsonschema as a direct run-time requirement in the file reqirements.txt along with a comment # resolve ambiguity with build-time dependency, and then to run make requirements_update to remove the package as a transitive run-time requirement.

There is a separate category for requirements that need to be installed before any other dependency is installed, either run-time or build-time, in order to ensure that the remaining dependencies are resolved and installed correctly. We call that category pip requirements and don't distinguish between direct or transitive requirements in that category.

12. Making wheels

Note: Support for custom wheels is currently disabled. We don't currently have any dependencies for which a binary wheel is unavailable. We'll leave this section in place until support is needed and enabled again

Some of Azul's dependencies contain native code that needs to be compiled into a binary executable which is then dynamically loaded into the Python interpreter process when the package is imported. These dependencies are commonly distributed in the form of wheels. A wheel is a Python package distribution that contains the pre-compiled binary code for a particular operating system and processor architecture combination, aka platform. Many such packages lack a wheel for the linux_x86_64 platform that Lambda functions execute on. Chalice will attempt to build the wheel on the fly during chalice package (make -C lambdas) but only if invoked on a system with linux_x86_64. On macOS, Chalice will fail to build a wheel for the linux_x86_64 platform but only prints a warning that's easily missed. The deployed Lambda will likely fail with an import error.

If you add a dependency on a package with native code, you need to build the wheel manually:

(.venv) ~/workspace/hca/azul$ docker run -it -v ${project_root}/:/root/azul python:3.11.6-bullseye bash

root@97804cb60d95:/# pip --version
pip 22.0.4 from /usr/local/lib/python3.11/site-packages/pip (python 3.11)

root@97804cb60d95:/# cd /root/azul/lambdas/.wheels

root@97804cb60d95:~/azul/lambdas/.wheels# pip wheel jsonobject==2.0.0
Collecting jsonobject==2.0.0
  Downloading jsonobject-2.0.0.tar.gz (402 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 403.0/403.0 KB 9.0 MB/s eta 0:00:00
  Preparing metadata (setup.py) ... done
Collecting six
  Downloading six-1.16.0-py2.py3-none-any.whl (11 kB)
Saved ./six-1.16.0-py2.py3-none-any.whl
Building wheels for collected packages: jsonobject
  Building wheel for jsonobject (setup.py) ... done
  Created wheel for jsonobject: filename=jsonobject-2.0.0-cp39-cp39-linux_x86_64.whl size=1606493 sha256=7f69b1ef612e13265ea95817e24b7d33ec63f07c0924f8c8692ee689679e1a18
  Stored in directory: /root/.cache/pip/wheels/c1/1b/00/8958e64a98b73db2ca8d997a7034c93b545cdcf30054aa7e43
Successfully built jsonobject

root@97804cb60d95:~/azul/lambdas/.wheels# ls -l
total 1584
-rw-r--r-- 1 root root 1606493 May 10 00:35 jsonobject-2.0.0-cp39-cp39-linux_x86_64.whl
-rw-r--r-- 1 root root   11053 May 10 00:35 six-1.16.0-py2.py3-none-any.whl

root@97804cb60d95:~/azul/lambdas/.wheels# exit
exit

(.venv) ~/workspace/hca/azul$ ls -l lambdas/.wheels
total 1584
-rw-r--r-- 1 root root 1606493 May  9 17:35 jsonobject-2.0.0-cp39-cp39-linux_x86_64.whl
-rw-r--r-- 1 root root   11053 May  9 17:35 six-1.16.0-py2.py3-none-any.whl

(.venv) ~/workspace/hca/azul$ sudo chown -R `id -u`:`id -g` lambdas/.wheels

(.venv) ~/workspace/hca/azul$ ls -l lambdas/.wheels
total 1584
-rw-r--r-- 1 hannes hannes 1606493 May  9 17:35 jsonobject-2.0.0-cp39-cp39-linux_x86_64.whl
-rw-r--r-- 1 hannes hannes   11053 May  9 17:35 six-1.16.0-py2.py3-none-any.whl
(.venv) ~/workspace/hca/azul$ 

Then modify the wheels target in lambdas/*/Makefile to unzip the wheel into the corresponding vendor directory.

Also see https://chalice.readthedocs.io/en/latest/topics/packaging.html

13. Development tools

13.1 OpenAPI development

To assist with adding documentation to the Azul Service OpenAPI page we can run the service app locally:

make -C lambdas/service local

The script serves the Swagger editor locally at a URL where your current version of the API documentation is visible. Change the docs in azul/service/app.py, save, refresh the page, and your changes will appear immediately.

13.2 Tracking changes to the OpenAPI definition

Changes to the OpenAPI definition are tracked in the source tree. When making changes that affect the definition, run:

make -C lambdas openapi

and commit any modifications to the openapi.json file. Failure to do so will break continuous integration during make check_clean.