GitHub Actions Cheat Sheet
Overview
GitHub Actions is a continuous integration and continuous delivery (CI/CD) platform that enables automated build, test and deployment pipelines. GitHub Actions also enables the execution of non-CI/CD type automation on a repository, like adding a label when someone creates a new issue on the repository. GitHub Actions supports Linux, Windows and macOS operating systems
Terminology
Event(s) - A specific activity in a repository that triggers a workflow execution
- Examples:
- A user creates a pull request
- A user opens an issue
- A user pushes a commit to a repository
- Other example events that trigger workflows
Workflow(s) - A configurable automated process
- Made up of one or more jobs
Defined by a YAML associated to a repository
- Found in
.github/workflows - A given repo can have multiple workflows
- Found in
Runs when:
- Triggered by an event in a repository
- Triggered manually
- Triggered via another workflow (workflows can reference other workflows)
- Posting to a REST API
- Per a defined schedule
Examples:
- A workflow to build and test pull requests
- A workflow to deploy your application every time a release is created
- A workflow to add a label every time someone opens a new issue
Runner(s) - A server that runs your workflows when they are triggered
- A given runner can execute a single job at a time
- Ubuntu Linux, Windows and macOS provided (hosted) by GitHub
- Each workflow runs on a fresh, newly-[provisioned virtual machine
- Runners come in different configurations to meet specific needs
- Users can leverage GitHub hosted or self-hosted runners
Job(s) - A set of steps in a workflow that execute on the same runner
Each job runs within a virtual machine (runner) OR container
Jobs can be configured to depend upon one another
Each job contains one or more step(s)
Runs when:
- Invoked within a workflow
- When the prior / dependent job within the workflow finishes
- Simultaneously with another job within the workflow
- In the context of a matrix
Examples:
- Separate, unique build jobs for different architectures
- A packaging job
- A deployment job
Step(s) - Granular execution of a job
- Steps can be either a shell script or an Action
- Data can be shared from one step to another
- Runs when:
- Invoked within a job
- When the prior step finishes Examples:
- A step that builds your application
- A step that pushes an artifact to the artifact repository
Action(s) - A custom application for the GitHub Actions platform that performs a complex but frequently repeated task
- Reduces the amount of repetitive code written in Workflow files
- Actions can be self-created / customized, or provisioned from the GitHub Marketplace.
Examples:
- Pull a given git repository for GitHub
- Set up the correct toolchain for a build environment
- Establish authentication to a cloud provider
That’s all for now. Consider “Intro to GitHub Actions” complete, but there’s a long ways to go and lots more to learn.