I recently set aside some time to write my first GitHub Action. I used my personal blog as my test case. It is a static site that is built with Wyam and hosted in Firebase.
TL;DR: skip down to the bottom for the full script.
What are GitHub Actions?
GitHub actions are workflows that can react to events raised in your repository. Pushing to a branch, opening a pull request, and opening an issue are examples of events that can trigger your workflow.
In my case, my workflow reacts to pushing to the master branch.
The workflow contains one or more jobs that run on Docker containers. Jobs contain one or more steps that carry out the tasks to perform the required action.
My workflow
The high-level set of steps that I need to perform are:
- Check out the code.
- Generate the site.
- Package the site.
- Push that package to my Octopus instance.
Some of these steps require other steps to run first. I'll need steps to install .NET Core, Wyam, and the Octopus CLI. I also need a step to calculate a version for my site package.
Workflow creation
Creating a new workflow was pretty intuitive. I went to the Actions tab of my repository and clicked the New workflow button.
There are some starter workflows that you can choose. I skipped those and went with the Set up a workflow yourself option.
GitHub launched me into an editor for a new YAML file in the .github/workflows/ folder of my repository.
Here are the changes I made to that file.
Name and trigger
I kept the default name CI and the trigger for pushes to the master branch:
name: CI
on:
push:
branches: [ master ]
Generate job
I renamed the default job from build to generate and accepted the image it runs on: ubuntu-latest:
jobs:
generate:
runs-on: ubuntu-latest
Checkout step
Below is the most minimal step you can add to a job. In this one line, I defined a step that checks out my repository to the Ubuntu container hosting the job.
Reusing steps is a key feature of Actions and many other YAML based pipelines. I use version 2 of the checkout step provided by the GitHub Actions team. You can also author actions and use third party actions in your workflows:
steps:
- uses: actions/checkout@v2
Workflow commands and environment variables
Actions provide workflow commands that you can use in your steps with a special string format passed to echo.
This step is called Set version and creates a package version based on the current date and the current run number of the workflow. The package version is saved as $PACKAGE_VERSION using the set-env command. $PACKAGE_VERSION is now available in the steps that create and publish the package:
- name: Set version
run: echo "::set-env name=PACKAGE_VERSION::$(date +'%Y.%m.%d').$GITHUB_RUN_NUMBER"
Generate the site
To generate my static site, I need to install .NET Core, the Wyam tool, and call Wyam against my source.
I use another built-in action actions/setup-dotnet@v1 to install .NET Core on the container. This step accepts a parameter for the .NET version to install:
- name: Setup .NET Core
uses: actions/setup-dotnet@v1
with:
dotnet-version: 2.1.802
With .NET installed, I can call the CLI to install the Wyam tool onto the container:
- name: Install Wyam
run: dotnet tool install --tool-path . wyam.tool
Finally, the Generate site step calls Wyam to generate the site:
- name: Generate site
run: ./wyam build -r blog -t Stellar src
Package and publish the site
I need the Octopus CLI to package and publish the site. I hopped over to the Octopus CLI download page and copied the script for installing it on Ubuntu:
- name: Install Octopus CLI
run: |
sudo apt update && sudo apt install --no-install-recommends gnupg curl ca-certificates apt-transport-https && \
curl -sSfL https://apt.octopus.com/public.key | sudo apt-key add - && \
sudo sh -c "echo deb https://apt.octopus.com/ stable main > /etc/apt/sources.list.d/octopus.com.list" && \
sudo apt update && sudo apt install octopuscli
I copy the necessary files into a directory representing the package. Then I call the octo pack command to create a Zip package with the version set to $PACKAGE_VERSION:
- name: Package blog.rousseau.dev
run: |
mkdir -p ./packages/blog.rousseau.dev/src/
cp .firebaserc firebase.json ./packages/blog.rousseau.dev/
cp -avr ./src/output ./packages/blog.rousseau.dev/src/
octo pack --id="blog.rousseau.dev" --format="Zip" --version="$PACKAGE_VERSION" --basePath="./packages/blog.rousseau.dev" --outFolder="./packages"
A snippet of the output from this step looks like:
Setting Zip compression level to Optimal
Packing blog.rousseau.dev version "2020.04.08.21"...
Saving "blog.rousseau.dev.2020.04.08.21.zip" to "./packages"...
Adding files from "./packages/blog.rousseau.dev" matching pattern "**"
With the package created, I call the octo push command to upload the package to my Octopus instance. My server URL and API key are configured as secrets in my repository to keep them safe and secure:
- name: Push blog.rousseau.dev to Octopus
run: octo push --package="./packages/blog.rousseau.dev.$PACKAGE_VERSION.zip" --server="${{ secrets.OCTOPUS_SERVER_URL }}" --apiKey="${{ secrets.OCTOPUS_API_KEY }}"
On the topic of API keys, I highly recommend setting up a service account when integrating another application with Octopus. There's a built-in Build server role that you can use for CI service accounts.
The results below show the request is authenticating as GitHub (a service account) instead of my user account.
The package that was created in the package step was successfully pushed to Octopus. Now I can deploy my site to Firebase (but that is a post for another time):
Detected automation environment: "NoneOrUnknown"
Space name unspecified, process will run in the default space context
Handshaking with Octopus Server: ***
Handshake successful. Octopus version: 2020.1.6; API version: 3.0.0
Authenticated as: GitHub (a service account)
Pushing package: /home/runner/work/blog.rousseau.dev/blog.rousseau.dev/packages/blog.rousseau.dev.2020.04.08.21.zip...
Requesting signature for delta compression from the server for upload of a package with id 'blog.rousseau.dev' and version '2020.04.08.21'
Calculating delta
The delta file (60,053 bytes) is 0.42 % the size of the original file (14,338,268 bytes), uploading...
Delta transfer completed
Push successful
Full script
name: CI
on:
push:
branches: [ master ]
jobs:
generate:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
- name: Set version
id: set-version
run: echo "::set-env name=PACKAGE_VERSION::$(date +'%Y.%m.%d').$GITHUB_RUN_NUMBER"
- name: Setup .NET Core
uses: actions/setup-dotnet@v1
with:
dotnet-version: 2.1.802
- name: Install Wyam
run: dotnet tool install --tool-path . wyam.tool
- name: Generate site
run: ./wyam build -r blog -t Stellar src
- name: Install Octopus CLI
run: |
sudo apt update && sudo apt install --no-install-recommends gnupg curl ca-certificates apt-transport-https && \
curl -sSfL https://apt.octopus.com/public.key | sudo apt-key add - && \
sudo sh -c "echo deb https://apt.octopus.com/ stable main > /etc/apt/sources.list.d/octopus.com.list" && \
sudo apt update && sudo apt install octopuscli
- name: Package blog.rousseau.dev
run: |
mkdir -p ./packages/blog.rousseau.dev/src/
cp .firebaserc firebase.json ./packages/blog.rousseau.dev/
cp -avr ./src/output ./packages/blog.rousseau.dev/src/
octo pack --id="blog.rousseau.dev" --format="Zip" --version="$PACKAGE_VERSION" --basePath="./packages/blog.rousseau.dev" --outFolder="./packages"
- name: Push blog.rousseau.dev to Octopus
run: octo push --package="./packages/blog.rousseau.dev.$PACKAGE_VERSION.zip" --server="${{ secrets.OCTOPUS_SERVER_URL }}" --apiKey="${{ secrets.OCTOPUS_API_KEY }}"
Conclusion
GitHub Actions are an excellent way to add continuous integration and delivery directly to your projects hosted on GitHub. When combined with the Octopus CLI, you've got a powerful onramp to repeatable, reliable deployments.
This post was originally published at octopus.com.
Top comments (0)