ubuntu-24.04 is available, 20.04 may obsolete in the future

[badlop]

Ubuntu runners

GitHub Actions provides several runners where we can run our workflows:

• ubuntu-20.04 includes Erlang/OTP 24
• ubuntu-22.04 doesn't include Erlang/OTP (Public Beta) Ubuntu 22.04 is now available actions/runner-images#5490
• ubuntu-24.04 doesn't either

Now that GitHub is considering ubuntu-24.04 as ubuntu-latest, it is expected that in the near future ubuntu-20.04 will be marked as obsolete. Once that time arrives, we will have to upgrade our actions from ubuntu-20.04 to ubuntu-22.04 or higher.

Erlang/OTP install methods

When the runner doesn't include Erlang/OTP (for example ubuntu-22.0.4 and higher), or we want to use a specific erlang version, our workflows use two alternative methods to install Erlang, depending on the requirements of the workflow:

A) Erlang Docker container, only suitable for simple tasks; doesn't work with complex tasks like ejabberd's ci, runtime...

jobs:

  tests:
    strategy:
      matrix:
        otp: [20, 25, 26, 27]
    container:
      image: erlang:${{ matrix.otp }}

B) erlef/setup-beam action is suitable for complex tasks, but in ubuntu-22.04 the lower erlang supported is 24.2.

jobs:

  tests:
    name: Tests
    strategy:
      matrix:
        otp: ['23.0', '25', '26', '27']
        elixir: ['1.13', '1.15', '1.16', '1.17']

    steps:

    - name: Get specific Erlang/OTP
      uses: erlef/setup-beam@v1
      with:
        otp-version: ${{matrix.otp}}
        elixir-version: ${{matrix.elixir}}

Our Ubuntu usage

This is a summary of what we are using right now:

repository	workflow	job	runs-on	erlang install method
ejabberd	ci.yml	tests	20.04 ⚠️	setup-beam
ejabberd	container.yml	container	22.04	not needed
ejabberd	installers.yml	binaries	22.04	not needed
ejabberd	installers.yml	release	22.04	not needed
ejabberd	runtime.yml	rebars	22.04	container
ejabberd	runtime.yml	rebar3-elixir	20.04 ⚠️	setup-beam
ejabberd	runtime.yml	mix	20.04 ⚠️	setup-beam
ejabberd-contrib	ci.yml	tests	20.04 ⚠️	setup-beam
docker-ejabberd	tests.yml	tests	22.04	not needed
docs	ci.yml	deploy	latest	not needed
ejabberd-api	build.yml	build	latest	not needed
xmpp	ci.yml	tests	22.04	container
others (cache_tab, eimp, ...)	ci.yml	tests	20.04/22.04 ⚠️	container

As ejabberd supports from Erlang/OTP 20.0 up, for complex tests like ejabberd's ci and runtime, we need to use ubuntu-20.04. In ubuntu-22.04 there's no way to install Erlang/OTP older than 24.2 to use it for complex tests.

What to expect in the future

As mentioned in actions/runner-images#10636

We support two latest LTS Ubuntu versions, so Ubuntu 22 will still be available in near future.

In the future when ubuntu-20.04 runner is deleted and we are forced to use ubuntu-22.04, I expect that there will be no way to test ejabberd with Erlang/OTP lower than 24.2. When that time arrives, we may have to raise the Erlang/OTP requirement in ejabberd to 24.2.