DEV Community

loading...
Cover image for Understanding how to use Github Actions

Understanding how to use Github Actions

zellwk profile image Zell Liew 🤗 ・8 min read

Github Actions is a Continuous Integration (CI) + Continuous Deployment (CD) tool by Github.

CI and CD are bombastic terms, but they simply mean the following:

  • Continuous Integration: People push to a Git repository and the code gets tested automatically.
  • Continuous Delivery: The pushed code (ideally tested and bug-free) is then pushed into the server so it becomes live for users.

Although Github Actions is one of the many CI + CD Tools out there, it's probably the simplest one to use (in my experience). Unfortunately, the Github Actions docs is a complete mess — they keep pointing you to different pages, expecting you to read everything (and understand everything) when you're still trying to set up your first action.

Today I want to share the basics of using Github Actions so it becomes easy for you to use it.

Setting Up Your First Github Action

Github Actions live in a .github/workflows folder. You can create any number of actions. Each action is a file. Since Github Actions use the YAML format, make sure you end the file name with a yml extension.

- .github
  |- workflows
    |- action1.yml
    |- action2.yml
Enter fullscreen mode Exit fullscreen mode

You can name the action file anything you want. These file names will show up in the Actions Tab once the action has run. (I'll show you where in a bit).

In the Github Action file, you need three properties.

  • name — name of the Github Action (so you know which action is running)
  • on — when to run this event.
  • jobs — what to do when we run this action.

The minimum configuration looks like this:

name: first-github-action
on: [push]
jobs:
  write-to-console:
    runs-on: ubuntu-latest
    steps:
      - run: echo 'Hello world!'
Enter fullscreen mode Exit fullscreen mode

This action runs when you push something into your Github repository.

Viewing the Action

You can view the Github Action in the Actions tab.

github actions tab location

Once you're in this actions tab, you'll see the name of your actions on the left sidebar. This corresponds to the name field you used for the action file.

On the right, you'll see a list of times where the action ran. In this case, I have one commit that ran the action.

github run actions location

Note: Workflows and actions mean the same thing here — I guess Github use the term Workflows because having the term "actions" everywhere makes things confusing.

If you click into the workflow that ran, you'll see a summary of what happened. This is where your job and action file name shows up.

job and action file name

If you click into the job, you will see a page that logs what happened during this workflow. (You can click on either of the write-to-console buttons here, they both link you to the same page).

write to console buttons

You can then click on any item to see more details. For example, here's what happens when I click on Run echo 'Hello world!'.

view action item

Now you know how to view your actions, we can look at the range of possible events next.

Github Action Events

Github Action Events determine when a workflow runs. The most basic event is a push, which means the workflow runs whenever something is pushed to the repository.

on: [push]
Enter fullscreen mode Exit fullscreen mode

You can find a list of the possible events to run on the "Events that trigger workflows" page. The list of possible events is shown on the right hand corner. Feel free to click on any item to read more details about the event.

events that triffer workflows

Of this list of events, I suspect most people would use push and schedule the most. I'll talk about schedule in a later article.

Running on a specific branch

You can only ask Github to run an action on specific branches if you provide that branch into push. Here's what the configuration looks like:

on: 
  push: 
    branches: 
      # When someone push to `main` branch
      - main
      # When someone pushes to `develop` branch
      - develop
      # When someone pushes to a branch within the `features` folder
      - 'features/**'
Enter fullscreen mode Exit fullscreen mode

Next let's talk about jobs.

Github Action Jobs

Jobs let you define what to do. Each job begins with a "Job ID". This ID is basically a slug you use. In this case, we have a write-to-console Job id.

jobs:
  write-to-console:
    # ... 
Enter fullscreen mode Exit fullscreen mode

If you're a bit more of a perfectionist, you can add a name attribute to this job. If you do so, the name will show up in the Github Actions page instead of the job ID.

jobs:
  write-to-console:
    name: Write to console
      # ...
Enter fullscreen mode Exit fullscreen mode

job ID name change

You can list multiple jobs if you wish to.

jobs:
  testing:
    # ...
  deploy: 
    # ...
Enter fullscreen mode Exit fullscreen mode

Running on a specific operating system

Each Job runs on a specific operating system. You can choose from Windows, Mac or Ubuntu (Linux) at the time of writing. These servers are called "runners" in Github Actions terminology.

You can find the updated list of supported operating systems here.

github supported runners

If we wish to run on Ubuntu, we simply add ubuntu to runs-on.

# ...
jobs:
  write-to-console:
    runs-on: ubuntu-latest
Enter fullscreen mode Exit fullscreen mode

Next we need to define the steps to run. This is where the bulk of the action occurs.

Defining what to do in each job

steps let you define what to run in each job. There are three ways to define steps.

  • With uses
  • With run
  • With name

Here's an example of what each of these looks like

# ...
jobs:
  write-to-console:
    # ... 
    steps: 
      # Method 1 with Uses
      - uses: something

      # Method 2 with Runs
      - runs: some-cli-command

      # Method 3 with name
      - name: Label for this step
        run: some-cli-command
Enter fullscreen mode Exit fullscreen mode

We'll dive into each possible syntax.

Running steps with uses

uses let you use Github Actions others have created. You can see a list of possible Github Actions in the Marketplace.

Pay attention to these two types of actions:

  • by actions — these are created by the Github actions team
  • The verified checkmark — these are created by people verified by the Github actions team.

These actions would thus be more stable than anything else you'll find on the marketplace.

marketplace actions by github actions team

marketplace verified actions

The most basic action is checkout, which lets you checkout the Git repository into your runner of choice. You can look at the marketplace page to find out how to use this action.

In this case, the Checkout page says we can use the action with actions/checkout@v2.

checkout page action

You can then provide arguments to the action with the with keyword.

steps: 
  - uses: actions/checkout@v2
    with: 
      repository: '' 
      anotherArg: '' 
Enter fullscreen mode Exit fullscreen mode

Pay attention to the syntax here:

  • uses has - in front of it — this signifies the step.
  • with does not have - in front of it — all other commands under the same step (with is within uses) should NOT have a - prefix.

The @v2 part is the version we're using. You can see a list of available versions on the top right hand corner, by click the latest-version dropdown.

latest version dropdown

I recommend stating the major version number (the first number that comes after v) with all Github Actions because we follow Semver here. Doing so will ensure your workflow won't break when the action introduces a breaking change.

Besides checkout, you'll most probably need to setup a Node Environment with the official action too.

steps:
  - uses: actions/checkout@v2
  - uses: actions/setup-node@v2
    with:
      node-version: '14'
Enter fullscreen mode Exit fullscreen mode

uses will simply be logged as a section in the Action log

items run with uses

Running steps with run

run is straightforward here. It simply runs a command. Each run command will create a dedicated section in the Actions log.

steps:
  # ...
  - run: echo 'Hello World!' 
  - run: echo "Another section 😉"
Enter fullscreen mode Exit fullscreen mode

sections created with run

Running steps with name

name lets you create a custom label for the steps you want to run. Each name should come with either a set of commands — typically with or run.

steps:
  # ...

  # Using Name + uses
  - name: Setup Node 
    uses: actions/setup-node@v1

  # Using Name + Run
  - name: Say Hello 
    run: echo 'Hello World!' 
Enter fullscreen mode Exit fullscreen mode

custome label created with name

Running multiple commands within one run command

You can run many lines of commands within a single run command. This helps group related things together and makes it easy to view the logs later.

To do this, you need a | character at the start of the run command. Then, you write each command on a new line.

steps:
  # ...
  - name: Command Group
    run: | 
      echo 'Hello World!' 
      echo 'Hello again!'
Enter fullscreen mode Exit fullscreen mode

multiple commands under a single run command

Wrapping Up

You now know the very basics of Github Actions. I hope this article clarifies things so you spend less time reading through the docs and configuring what you want to create.

Next week, we'll dive deeper into Github actions to show you how to deploy a site automatically with SSH into a server. This means we'll also begin to work with Github secrets 😉.




Thanks for reading. This article was originally posted on my blog. Sign up for my newsletter if you want more articles to help you become a better frontend developer.

Discussion (2)

pic
Editor guide
Collapse
tilkinsc profile image
Cody Tilkins

Wish I found this a few months ago when I was setting up my CI. I had to pan through a lot of unnecessary text just to find out specifics on something just to have it say the gist of it.

Collapse
labibllaca profile image
labibllaca

Reading your article is like charm. You have a great writing style.