I want to use mysql in a composite action, but it fails with:

ERROR 2013 (HY000): Lost connection to MySQL server at 'reading initial communication packet', system error: 2

It works fine when I run the steps directly in the workflow, but not when I want to have them defined in a composite action.

my workflow:

on:
  push:
    branches:
      - master

jobs:
  test-backend:
    runs-on: ubuntu-latest

    services:
      mysql:
        image: mysql:8.0
        ports:
          - 3306:3306
        env:
          MYSQL_DATABASE: 'test'
          MYSQL_ROOT_PASSWORD: 'root'

    strategy:
      matrix:
        suite: [ 'unit', 'job', 'api' ]
        shard: [ 1, 2, 3 ]
    steps:
      - name: Checkout code
        uses: actions/checkout@v4

      - name: Run ${{ matrix.suite }} tests with shard ${{ matrix.shard }}
        uses: ./.github/actions/test-backend
        with:
          test-suite: ${{ matrix.suite }}
          shard: ${{ matrix.shard }}
          total-shards: 3

and this is the composite action:

inputs:
  test-suite:
    description: 'Test suite to run (e.g., unit, api, job, acceptance, functional)'
    required: false
    default: ''
    type: string
  shard:
    description: 'Shard number to run'
    required: false
    default: 1
    type: number
  total-shards:
    description: 'Total number of shards'
    required: false
    default: 1
    type: number

runs:
  using: 'composite'
  steps:
    - name: Checkout code
      uses: actions/checkout@v4

    - name: Set up PHP
      uses: shivammathur/setup-php@v2
      with:
        php-version: '8.2'
        extensions: mbstring, intl, pdo_mysql
        coverage: none

    - name: Setup testing env variables
      working-directory: ./backend
      shell: bash
      run: |
        cp ./.env.testing.example ./.env.testing
        while IFS= read -r line || [ -n "$line" ]; do
          echo "$line" >> $GITHUB_ENV
        done < ./.env.testing

    - name: Create databases
      working-directory: ./backend
      shell: bash
      run: sh create_databases.sh

    - name: Install Composer dependencies
      working-directory: ./backend
      shell: bash
      run: composer install --no-progress --no-suggest --prefer-dist --ignore-platform-reqs

    - name: Run migrations
      working-directory: ./backend
      shell: bash
      run: sh run_migrations.sh --force

    - name: Build Codeception helpers
      working-directory: ./backend
      shell: bash
      run: vendor/bin/codecept build

    - name: Run Codeception tests
      working-directory: ./backend
      shell: bash
      run: vendor/bin/codecept run ${{ inputs.test-suite }} --shard ${{ inputs.shard }}/${{ inputs.total-shards }}