GitHub Actions: Hello World

If you are looking for a flexible way to automate your DevOps workflows for your GitHub repositories, GitHub actions is where it’s at. GitHub Actions makes it easy to automate many of your workflows, especially in the world of DevOps. Even if you already have a DevOps story and workflows in place, it’s still worth taking some time to gain a better understanding of what GitHub Actions may offer your team. As with most getting started examples, a good Hello World sample is all you need to get started. The GitHub Learning Lab course GitHub Actions: Hello World gives you just that.

Where to Start

As you begin to dig into GitHub Actions it’s important to note two components involved in using GitHub Actions:

• the action itself

GitHub Actions help you automate your software development workflows in the same place you store code and collaborate on pull requests and issues. You can write individual tasks, called actions, and combine them to create a custom workflow.

• a workflow that uses action(s)

Workflows are custom automated processes that you can set up in your repository to build, test, package, release, or deploy any project on GitHub.

supporting files

In the Hello World getting started example the action that is created will make use of a Dockerfile in your repository and in this example that Dockerfile will invoke a bash script that will print out Hello World using provided inputs from the action.

In this case the Docerfile looks like this:

FROM debian:9.5-slim

ADD entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh
ENTRYPOINT ["/entrypoint.sh"]

And the supporting script that is invoked looks like this:

#!/bin/sh -l

sh -c "echo Hello world my name is $INPUT_MY_NAME"

In the example provided in the course, these supporting files live in the same directory as your action.yml

action.yml

An action requires a metdata file that uses YAML syntax. This file will define the inputs, outputs, and main entrypoint used to run your action.

An example of what this might look like is as follows:

name: "Hello Actions"
description: "Greet someone"
author: "octocat@github.com"

inputs:
  MY_NAME:
    description: "Who to greet"
    required: true
    default: "World"

runs:
  using: "docker"
  image: "Dockerfile"

branding:
  icon: "mic"
  color: "purple"

workflow files

Workflows are defined in special files in the .github/workflows directory, named main.yml. Workflows can execute based on a chosen event.

Workflows piece together jobs, and jobs piece together steps. Actions can be used from within the same repository, from any other public repository, or from a published Docker container image.

An example of what this might look like is as follows:

name: A workflow for my Hello World file
on: push

jobs:
  build:
    name: Hello world action
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v1
      - uses: ./action-a
        with:
          MY_NAME: "Mona"

Summary

If we look at the order of operations here, it is as follows:

Workflow File -> Action File -> Dockerfile -> Bash Script
     main.yml ->  action.yml -> Dockerfile -> entrypoint.sh

As you completed the referenced course you’ll have a working example of a GitHub Action. You will be able to see the results of this by clicking the Actions tab in your repository.

Be certain to check out the course GitHub Actions: Hello World for all of the details and start diving into exploring this awesome feature that GitHub offers.

I plan to start writing more posts on using GitHub Actions and wanted to be sure to put a starting point here for all who are just getting started.

Other Notable Links

Other links to check out that are noted in the course are below:

• Review the GitHub Actions documentation on the GitHub Developer site.
• Use existing actions from the GitHub Marketplace.
• Use existing actions from GitHub’s official actions community.
• Use actions created by others in awesome-actions.