Welcome to the course!

We'll learn how to create a workflow that enables Continuous Delivery. You'll:

create a workflow to deploy to staging based on a label
create a workflow to deploy to production based on merging to master

Before you start, you should be familiar with GitHub and Continuous Integration. If you aren't sure where to start, you may want to check out these two Learning Lab courses:

What is Continuous Delivery?

Martin Fowler defined Continuous Delivery very simply in a 2013 post as follows:

Continuous Delivery is a software development discipline where you build software in such a way that the software can be released to production at any time.

A lot of things go into delivering "continuously". These things can range from culture and behavior to specific automation. In this course, we're going to focus on deployment automation.

Setting up environments and kicking off deployments

Automation works at its best when a set of triggers work harmoniously to set up and deploy to target environments. Engineers at many companies, like at GitHub, typically use a ChatOps command as a trigger. The trigger itself isn't incredibly important.

In our use case, we'll use labels as triggers for multiple tasks:

When someone applies a "spin up environment" label to a pull request, that'll tell GitHub Actions that we'd like to set up our resources on an Azure environment.
When someone applies a "stage" label to a pull request, that'll be our indicator that we'd like to deploy our application to a staging environment.
When someone applies a "destroy environment" label to a pull request, we'll tear down any resources that are running on our Azure account.

For now, we'll focus on staging. We'll spin up and destroy our environment in a later step.

Step 1: Configure a trigger based on labels

In a GitHub Actions workflow, the on step defines what causes the workflow to run. In this case, we want the workflow to run whenever a label is applied to the pull request.

:keyboard: Activity: Configure the workflow trigger based on a label being added

Edit the deploy-staging.yml file on this branch, or use this quick link (We recommend opening the quick link in another tab)
Change the name of the directory CHANGETHIS to workflows, so the title of this file with the path is .github/workflows/deploy-staging.yml. If you're working on the GitHub.com user interface, see the suggestion below for how to rename.
Edit the contents of this file to trigger a job called build on a label

Changing the name of a directory

If you're working locally, rename your file or drag-and-drop the file into the proper directory as you'd normally do. If you're working on GitHub.com, you can change the name of a directory by changing its filename and using the Backspace key until you reach the directory, as follows: 1. In the file name field, click in front of the first character in the file name 1. Press Backspace or Delete on your keyboard until you see the path you want to keep. You can continue to press Backspace even if the text box with the file name is empty. 1. Enter the new name for your directory. 1. Enter `/` to let GitHub know this should be a new directory.

Your resulting file should be in .github/workflows/deploy-staging.yml and it should look like this:

name: Stage the app

on: 
  pull_request:
    types: [labeled]

jobs:
  build:
    runs-on: ubuntu-latest

I'll respond when you push a commit on this branch.

Job conditionals

GitHub Actions features powerful controls for when to execute jobs and the steps within them. One of these controls is if, which allows you run a job only when a specific condition is met. See jobs.<job_id>.if in Workflow syntax for GitHub Actions for more information.

Using information within GitHub

Workflows are part of the GitHub ecosystem, so each workflow run gives you access to a rich set of data that you can use to take fine-grained control.

We'd like to run our workflow on a specific label name, suppose that it's peacock. We can run the workflow based on that labels name with the following single line that packs a punch: if: contains(github.event.pull_request.labels.*.name, 'peacock'). Here's how it works:

if: is the conditional that will decide if the job will run
contains() is a function that allows us to determine if a value like say, a label named "peacock", is contained within a set of values like say, a label array ["bug", "stage", "peacock", "feature request"]
github.event.pull_request.labels is specifically accessing the set of labels that triggered the workflow to run. It does this by accessing the github object, and the pull_request event that triggered the workflow.
github.event.pull_request.labels.*.name uses object filters to filter out all information about the labels, like their color or description, and lets us focus on just the label names.

Step 2: Trigger a job on specific labels

Let's put all this together to run our job only when a labeled named "stage" is applied to the pull request.

:keyboard: Activity: Add a conditional to select from labels

Edit the deploy-staging.yml file on this branch, or use this quick link (We recommend opening the quick link in another tab)

Edit the contents of the file to add a block for environment variables before your jobs, as follows.

env:
  DOCKER_IMAGE_NAME: renesansz-azure-ttt
  IMAGE_REGISTRY_URL: docker.pkg.github.com
  #################################################
  ### USER PROVIDED VALUES ARE REQUIRED BELOW   ###
  #################################################
  #################################################
  ### REPLACE USERNAME WITH GH USERNAME         ###
  AZURE_WEBAPP_NAME: renesansz-ttt-app
  #################################################

Edit the contents of the file to add a conditional that filters the build job using a label called "stage".

Your results should look like this:

name: Stage the app

on: 
  pull_request:
    types: [labeled]

env:
  DOCKER_IMAGE_NAME: renesansz-azure-ttt
  IMAGE_REGISTRY_URL: docker.pkg.github.com
  #################################################
  ### USER PROVIDED VALUES ARE REQUIRED BELOW   ###
  #################################################
  #################################################
  ### REPLACE USERNAME WITH GH USERNAME         ###
  AZURE_WEBAPP_NAME: renesansz-ttt-app
  #################################################

jobs:
  build:
    runs-on: ubuntu-latest

    if: contains(github.event.pull_request.labels.*.name, 'stage')