Closed himanshuupadhyay101 closed 3 years ago
GitHub Actions is a unique world that lives alongside your repository. It is one made up of many moving parts and having a general understanding of these parts will help us understand the behavior we are going to program into our action.
From 30,000 feet GitHub Actions is made up of the following components, with each component having its own complexities:
Component | Description |
---|---|
Action | Individual tasks that you combine as steps to create a job. Actions are the smallest portable building block of a workflow. To use an action in a workflow, you must include it as a step. |
Artifact | Artifacts are the files created when you build and test your code. Artifacts might include binary or package files, test results, screenshots, or log files. Artifacts can be used by the other jobs in the workflow or deployed directly by the workflow. |
Event | A specific activity that triggers a workflow run. |
Job | A defined task made up of steps. Each job is run in a fresh instance of the virtual environment. Jobs can run at the same time in parallel or be dependent on the status of a previous job and run sequentially. |
Runner | Any machine with the GitHub Actions runner application installed. You can use a runner hosted by GitHub or host your own runner. A runner waits for available jobs. Runners run one job at a time reporting the progress, logs, and final result back to GitHub. |
Step | A step is a set of tasks performed by a job. Steps can run commands or actions. |
Virtual Environment | The virtual environment of a GitHub-hosted runner includes the virtual machine's hardware configuration, operating system, and installed software. |
Workflow | A configurable automated process that you can set up in your repository. Workflows are made up of one or more jobs and can be scheduled or activated by an event. |
When a repository is configured with a workflow file, like we just created, the following series of events occurs.
I'm glad you asked. Let's take a look at the workflow file that we just committed to this repository.
name: CI
on: [push]
jobs:
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v1
- name: Run a one-line script
run: echo Hello, world!
- name: Run a multi-line script
run: |
echo Add other actions to build,
echo test, and deploy your project.
This file is made up of a series of metadata, as well as behaviors that we wish to happen when the workflow is triggered.
Let's take a second to talk about each of the pieces that we see here:
name: CI
CI
on: [push]
Jobs:
build
runs-on: ubuntu-latest
uses: actions/checkout@v1
name: Run a one-line script
run: echo Hello, world!
name: Run a multi-line script
run: |
echo Add other actions to build,
echo test, and deploy your project.
๐Take a deeper dive into workflow components ๐Read more about configuring workflows
As I mentioned earlier, a step is a task that is either an action or a command. This can be slightly confusing, so I want to take a little time to ensure I explain it to you before moving on.
Actions are powerful. They are small programs written in either JavaScript or running inside of Docker containers, that add some functionality to your repository.
The things you can do with actions are limited only by your imagination. Want to send a tweet every time you tag a release? What about ordering ๐just by creating an issue?
Let's not forget the more practical usage of actions, testing the source code of a repository or letting your team know that you are out of office ๐ when they @ mention your name in issues or pull requests.
You can define an action's inputs, outputs, and environment variables to create reusable building blocks for your workflow.
Actions are portable. You are free to publish your actions to the Actions Marketplace where others can use your creation in their workflows! You can also share actions without publishing them to the marketplace by referencing the repository that contains the actions code!
Actions can even run commands ๐
๐Learn more About Actions
Commands are useful in the own respect, but are much more limited than actions.
Think about the tasks you might do from the command line of your local machine. Maybe you run npm install
to install all of the dependencies for your project before running your unit tests. Maybe you run docker build
to execute a Dockerfile.
You can accomplish the same set of tasks inside of a workflow but using run
as a step in your job.
Commands are not easily shareable. There is no central location where you can consume the popular commands used in workflows. You do not have access to fine tuning the inputs, outputs or environment variables.
This does not mean commands offer no value in a workflow, but you should use them wisely and if you find yourself reusing the same commands repeatedly, consider turning them into actions.
Currently my-workflow.yml
is not set up correctly for our use-case. It worked great for allowing us to take a high-level look at workflows, but if we want to use our custom actions there are some changes that we have to make to it.
my-workflow.yml
Edit the .github/workflows/my-workflow.yml
so that it has the contents below:
name: Docker Actions
on: [push]
jobs:
action:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v1
Commit these file changes to this branch
I'll respond when you push changes to this pull request.
@himanshuupadhyay101 you're doing great so far ๐! You've had to do a lot of workflow set up so we can begin writing custom actions. We have just one more thing to add to our my-workflow.yml
file before we get to the action side of things.
Before we make our final workflow change let's do a quick recap about what we've done.
Action | Key Takeaways |
---|---|
Created my-workflow.yml inside of .github/workflows directory |
GitHub repositories look in the .github/workflows folder for workflow files. |
Used a templated workflow | GitHub provides many templates for workflow files. This is a great spot to look when setting up a new workflow. If you can't find what you are looking for, you can always click the setup a workflow yourself button for a minimal starter template |
Workflow environment | You learned, from a high level, how a repository uses a workflow file to run commands or actions based on triggers. You also learned that where these commands or actions execute is something that can be specified |
Workflow syntax | You were briefly introduced to the workflow YAML syntax. |
If that seems like a lot of things just to get started... well, it is! GitHub Actions is a robust platform designed to automate a wide range of tasks for your repositories.
If you'd like to see more examples of workflows and actions then check out these Learning Lab courses all about GitHub Actions:
my-workflow.yml
Edit the my-workflow.yml
to have the following contents:
name: Docker Actions
on: [push]
jobs:
action:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v1
- name: hello-action
uses: ./.github/actions/hello-world
Commit these file changes to this branch
I'll respond when you push changes to this pull request.
You have triggered a workflow!
Great job adding the workflow. Adding that file to this branch is enough for GitHub Actions to begin running on your repository. The time this takes will vary based on the complexity of the workflow. At this point we can ignore the workflow because it doesn't do anything yet, but while this runs I'll briefly explain the components of the workflow you just added.
If you want to inspect your running workflow you can do so by heading over to the Actions tab of this repository.