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rails-lambda / crypteia

🧱🔐 Rust Lambda Extension for any Runtime/Container to preload Secure Environment Variables!
https://lamby.cloud
MIT License
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aws environment-variables lambda lambda-extensions nodejs php python ruby rust ssm-parameter-store

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🛡 Crypteia

Node Ruby PHP Python

Rust Lambda Extension for any Runtime to preload SSM Parameters as Secure Environment Variables!

Super fast and only performed once during your function's initialization, Crypteia turns your serverless YAML from this:

Environment:
  Variables:
    SECRET: x-crypteia-ssm:/myapp/SECRET

... into real runtime (no matter the lang) environment variables backed by SSM Parameter Store. For example, assuming the SSM Parameter path above returns 1A2B3C4D5E6F as the value, your code would return:

// node
process.env.SECRET; // 1A2B3C4D5E6F
# ruby
ENV['SECRET'] # 1A2B3C4D5E6F

We do this using our shared object library via the LD_PRELOAD environment variable in coordination with our Lambda Extension binary file. Unlike other AWS SSM Lambda Extension Solutions your code never needs to know where these environment variables come from. See the Installation and Usage sections for more details.

💕 Many thanks to the following projects and people for their work, code, and personal help that made Crypteia possible:

Architecture

There are two main parts for Crypteia, the crypteia binary and libcrypteia.so shared object file. The following sequence diagram should help highlight how this works with an image's ENTRYPOINT and CMD interface.

sequenceDiagram
  actor WRK as Container Workload
  participant ENT as 🚪 ENTRYPOINT
  participant BIN as 🗑 (bin) crypteia
  participant LIB as 📚 (lib) libcrypteia.so
  participant CMD as 📢 CMD
  participant AWS as 🔒 Secrets Storage
  WRK->>ENT: Run
  activate ENT
  ENT->>BIN: Lambda RIC or ENTRYPOINT
  activate BIN
  BIN->>AWS: Batch Fetch
  AWS->>BIN: Batch Response
  BIN->>BIN: crypteia.json (write)
  BIN->>WRK: 
  deactivate BIN
  deactivate ENT
  WRK->>CMD: Run
  activate CMD
  CMD->>LIB: LD_PRELOAD
  activate LIB
  LIB->>LIB: crypteia.json (read/delete)
  LIB->>CMD: 🔐 Shared Memory
  deactivate LIB
  CMD->>CMD: getenv(3)
  CMD->>WRK: 
  deactivate CMD

Secrets are fetched in batch via the ENTRYPOINT. This is done for you automatically with the Lambda Runtime Interface Client as part of the Lambda Extensions interface. When using Ctypteia with other container tools, calling the binary /opt/extensions/crypteia would need to be done as an explicit ENTRYPOINT or part of that script. When your CMD process is running, replacing x-crypteia prefixed environment values with getenv(3) is done quickly in memory.

Installation

When building your own Lambda Containers, use both the crypteia binary and libcrypteia.so shared object files that match your platform. Target platform naming conventions include the following:

Note 🦾 All of our images are multi-platform supporting both amd64 and arm64 for linux. We use Docker manifests and there is no need to use special tags.

Lambda Containers

There are two options for Lambda containers. The easiest is to use Docker's multi stage builds with our Extension Containers to copy the /opt directory matching your platform and Crypteia version number. example below. Remember to use -debian vs -amzn if you are using your own Linux containers. Or change the version number depending on your needs.

FROM ghcr.io/rails-lambda/crypteia-extension-amzn:1 AS crypteia
FROM public.ecr.aws/lambda/nodejs:18
COPY --from=crypteia /opt /opt
ENV LD_PRELOAD=/opt/lib/libcrypteia.so

Alternatively, you can download your platform's binary and shared object file from our Releases page and place them into your projects Docker build directory. Remember to remove the platform file suffix. Example:

RUN mkdir -p /opt/lib
RUN mkdir -p /opt/extensions
COPY crypteia /opt/extensions/crypteia
COPY libcrypteia.so /opt/lib/libcrypteia.so
ENV LD_PRELOAD=/opt/lib/libcrypteia.so

If you are using Python you will need to add our Crypteia python package to the PYTHONPATH in order for things to "just work". The result of this will be that os.environ["SECRET"], os.environ.get("SECRET"), and os.getenv("SECRET") will be routed to the getenv system call and therefore take advantage of the Crypteia rust extension.

ENV PYTHONPATH=/opt/crypteia/python

Warning When building your own Lambda Containers, please make sure glibc is installed since this is used by redhook.

Lambda Extension

Our Amazon Linux 2 files can be used within a Lambda Extension that you can deploy to your own AWS account as a Lambda Layer. You can use this project to build, publish, and deploy that layer since it has the SAM CLI installed. All you need to do is supply your own S3 bucket. The process differ slightly for arm64, but for both, open up the development container and start off by configuring the AWS CLI to access the account needed.

aws configure

The package/template.yml file has a the layer's CompatibleArchitectures set to x86_64. So these commands work without changes.

./amzn/setup
S3_BUCKET_NAME=my-bucket ./package/deploy

However, for arm64 the process would be a little different. First open the package/template.yml and change the CompatibleArchitectures value from x86_64 to arm64. Now run the following commands to publish the lambda layer. Optionally, if you want to create distinct layer names for each arch, feel free open up the package/deploy file and change the --stack-name as you see fit.

./amzn/setup-arm64
S3_BUCKET_NAME=my-bucket ./package/deploy

Other Containers

If you are using Crypteia on your own Docker containers without the Lambda Extension mechanics, you can simply set the ENTRYPOINT to the Crypteia binary which fetches your environment variables so the shared object preload can use them.

FROM ghcr.io/rails-lambda/crypteia-extension-amzn:1 AS crypteia
FROM ubuntu
COPY --from=crypteia /opt /opt
ENV LD_PRELOAD=/opt/lib/libcrypteia.so
ENTRYPOINT /opt/extensions/crypteia

Usage

First, you will need your secret environment variables setup in AWS Systems Manager Parameter Store. These can be whatever hierarchy you choose. Parameters can be any string type. However, we recommend using SecureString to ensure your secrets are encrypted within AWS. For example, let's assume the following paramter paths and values exist:

Crypteia supports two methods to fetch SSM parameters:

  1. x-crypteia-ssm: - [Single] path for a single environment variable.
  2. x-crypteia-ssm-path: - [Group] Path prefix to fetch many environment variables.

Using whatever serverless framework you prefer, and set up your function's environment variables using either of the two SSM interfaces from above. For example, here is an environment variables section for an AWS SAM template that demonstrates all of Crypteia's features.

Environment:
  Variables:
    # [Single] Example
    SECRET: x-crypteia-ssm:/myapp/SECRET
    ACCESS_KEY: x-crypteia-ssm:/myapp/access-key
    # [Group] Example
    X_CRYPTEIA_SSM: x-crypteia-ssm-path:/myapp/envs
    DB_URL: x-crypteia
    NR_KEY: x-crypteia

When your function initializes, each of the four environmet variables (SECRET, ACCESS_KEY, DB_URL, and NR_KEY) will return values from their respective SSM paths.

// node
process.env.SECRET;       // 1A2B3C4D5E6F
process.env.ACCESS_KEY;   // G7H8I9J0K1L2
process.env.DB_URL;       // mysql2://u:p@host:3306
process.env.NR_KEY;       // z6y5x4w3v2u1
# ruby
env["SECRET"];       ## 1A2B3C4D5E6F
env["ACCESS_KEY"];   ## G7H8I9J0K1L2
env["DB_URL"];       ## mysql2://u:p@host:3306
env["NR_KEY"];       ## z6y5x4w3v2u1

Here are a few details about how Crypteia works with respect to the internal implementation:

  1. When accessing a single parameter path via x-crypteia-ssm:, the environment variable name available to your runtime is used as is. No part of the parameter path influences the resulting name.
  2. When using x-crypteia-ssm-path:, the environment variable name can be anything and the value is left unchanged.
  3. The parameter path hierarchy passed with x-crypteia-ssm-path: must be one level deep and end with valid environment variable names. These names must match environement placeholders using x-crypteia values.

For security, the usage of DB_URL: x-crypteia placeholders ensures that your application's configuration is in full control of which dynamic values can be used with x-crypteia-ssm-path:.

Shown below is a simple Node.js 16 function which has the appropriate IAM Permissions and Crypteia extension via an installed Lambda Layer. Also configured are the necessary LD_PRELOAD and SECRET environment variables. The code in this function logs the value of the process.env.SECRET which correctly resolves to the value from SSM Parameter Store.

Screenshot of the Environment variables in the AWS Lambda Console showing `LD_PRELOAD` to `/opt/lib/libcrypteia.so` and `SECRET` to `x-crypteia-ssm:/myapp/SECRET`.

Screenshot of Code source in the AWS Lambda Console showing the `body` results of `1A2B3C4D5E6F` which is resolved from SSM Parameter Store.

Using Dynamic SSM Paths

Your template.yaml file can contain input Parameters that indicates the environment of the app. You can use this parameter to fetch the correct env variable in SSM depending on the environment you are deploying your app to. For exemple, a Lamby app has a RailsEnv parameter which is commonly set to to indicate the environment you running under:

Parameters:
  RailsEnv:
    Type: String
    Default: staging
    AllowedValues:
      - staging
      - production

This parameter can be used to fetch SSM-backed environment variables that leveage dynamic paths like /myapp/${RailsEnv}/MY_VARIABLE. The template.yaml file will then look like this example below. This way you can have one different SSM variable for each one of your environments in a single AWS account.

Environment:
  Variables:
    SECRET: x-crypteia-ssm:/myapp/${RailsEnv}/SECRET
    ACCESS_KEY: x-crypteia-ssm:/myapp/${RailsEnv}/access-key
    X_CRYPTEIA_SSM: x-crypteia-ssm-path:/myapp/${RailsEnv}/envs

IAM Permissions

Please refer to the AWS guide on Restricting access to Systems Manager parameters using IAM policies for details on which policies your function's IAM Role will need. These examples assume the /myapp prefix and should work for direct secrets in that path or further nesting in a path prefix as described in the usage section.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": ["ssm:Get*", "ssm:Describe*"],
      "Resource": "arn:aws:ssm:*:${AWS::AccountId}:parameter/myapp/*"
    }
  ]
}

Here is an example Policies section you could add to your AWS SAM template.yaml file.

Policies:
  - Statement:
    - Effect: Allow
      Action: ["ssm:Get*", "ssm:Describe*"]
      Resource:
        - !Sub arn:aws:ssm:*:${AWS::AccountId}:parameter/myapp/*

Note If you are not using the default encryption key, you will also need to add a KMSDecryptPolicy policy.

Troubleshooting

Crypteia has very verbose logging which is enabled via the CRYPTEIA_DEBUG environment variable:

CRYPTEIA_DEBUG: true

Example of logs:

{"All":"all","ErrorMessage":"","_aws":{"CloudWatchMetrics":[{"Dimensions":[["All","lib"]],"Metrics":[{"Name":"initialized","Unit":"Count"}],"Namespace":"Crypteia"}],"Timestamp":1670424178585},"initialized":1,"lib":"lib"}
{"All":"all","ErrorMessage":"","_aws":{"CloudWatchMetrics":[{"Dimensions":[["All","main"]],"Metrics":[{"Name":"initialized","Unit":"Count"}],"Namespace":"Crypteia"}],"Timestamp":1670424178590},"initialized":1,"main":"main"}
{"All":"all","ErrorMessage":"","_aws":{"CloudWatchMetrics":[{"Dimensions":[["All","main"]],"Metrics":[{"Name":"fetched","Unit":"Count"}],"Namespace":"Crypteia"}],"Timestamp":1670424178831},"fetched":1,"main":"main"}
{"All":"all","ErrorMessage":"","_aws":{"CloudWatchMetrics":[{"Dimensions":[["All","lib"]],"Metrics":[{"Name":"initialized","Unit":"Count"}],"Namespace":"Crypteia"}],"Timestamp":1670424178892},"initialized":1,"lib":"lib"}
{"All":"all","ErrorMessage":"","_aws":{"CloudWatchMetrics":[{"Dimensions":[["All","lib"]],"Metrics":[{"Name":"is_env_file","Unit":"Count"}],"Namespace":"Crypteia"}],"Timestamp":1670424179575},"is_env_file":1,"lib":"lib"}
{"All":"all","ErrorMessage":"","_aws":{"CloudWatchMetrics":[{"Dimensions":[["All","lib"]],"Metrics":[{"Name":"read_env_file","Unit":"Count"}],"Namespace":"Crypteia"}],"Timestamp":1670424179575},"lib":"lib","read_env_file":1}
{"All":"all","ErrorMessage":"","_aws":{"CloudWatchMetrics":[{"Dimensions":[["All","lib"]],"Metrics":[{"Name":"delete_file","Unit":"Count"}],"Namespace":"Crypteia"}],"Timestamp":1670424179575},"delete_file":1,"lib":"lib"}

Development

This project is built for GitHub Codespcaes using the Development Container specification. Even though Codespaces may not be available to everyone, this project's containers are simple for anyone to make work with any editor.

Our development container is based on the vscode-remote-try-rust demo project. For details on the VS Code Rust development container, have a look at the container's history. Once you have the repo cloned and set up with a dev container using Codespaces, VS Code, or the Dev Container CLI, run the following commands which will install packages, build your project, and run tests without needing to connect to SSM:

./bin/setup
./bin/test-local

If you want to test SSM with your AWS account, the AWS CLI is installed on the dev container. Set it up with your test credentials using the following. These will be passed thru to various build/test containers.

export AWS_ACCESS_KEY_ID=...
export AWS_SECRET_ACCESS_KEY=...
export AWS_REGION=...

You can also develop using the Amazon Linux 2 support. This will use Docker-in-Docker to download AWS SAM and Lambda images to build cryptia using what is present (e.g. glibc) in your environment:

./amzn/setup
./amzn/test

Using VS Code

If you have the Visual Studio Code Dev Container extension installed you can easily clone this repository locally, use the "Open Folder in Container..." command, and use the integrated terminal for your setup and test commands. Example:

VS Code showing the "Dev Containers: Open Folder in Container..." command.

VS Code window with the Crypteia project open in a dev container. Shown too are the tests running.

Dev Container CLI

You can use the open-source Dev Container CLI to mimic what Codespaces and/or VS Code are doing for you. In this way, you can use different editors. You must have Docker installed. Here are the commands to build the dev container and setup/test the project:

devcontainer build --workspace-folder .
devcontainer up --workspace-folder .
devcontainer run-user-commands --workspace-folder .
devcontainer exec --workspace-folder . ./bin/setup
devcontainer exec --workspace-folder . ./bin/test-local

Showing Sublime Text on a Mac using the Dev Container CLI to run Crypteia tests.