composer-install VS checkout

All you really have to do is persist this directory between individual CI runs. Check out https://github.com/ramsey/composer-install for an existing implementation.

Composer Install (GitHub Action)

checkout

To checkout the merged commit with actions/checkout on pull_request_target event, you need to get the pull request by GitHub API and set the merge commit hash to actions/checkout input ref.

If you re-run GHA after master changes, CI is testing over different code.

You can [disable](https://github.com/actions/checkout#checkout-pull-request-head-commit-instead-of-merge-commit) on the checkout action:

```

There was an outage yesterday too when the GitHub action “checkout@v3” broke when they released “checkout@v4”

Yes, they broke the ability for GitHub CI to checkout repos…

https://github.com/actions/checkout/issues/1448

The first two steps are setting up the job's environment. The checkout action will checkout out the repository at the triggering ref. The setup-python action will setup the desired Python runtime. My package supports Python 3.9+ so I'm targeting the minimum version for my build environments.

These first few steps demonstrate how you can run commands like npm install or import other workflows such as how it uses the actions/checkout to copy the contents of the repository into a working directory on the runner host. Read Reusable workflows for more about the syntax for referencing them.

Check out the repo: We will use the actions/checkout action to checkout the repository.

Take a look at the checkout action usage here https://github.com/actions/checkout

Then, we have two important initial steps to define. The first one is an official GitHub Action used to check-out a repository so a workflow can access it. The second one it's pretty more complex but, briefly, downloads and set up a requested version of Java.