Running 32-bit Images in GitLab CI
##################################

:category:  Misc
:date:      2023-09-07 16:03:00 +0300
:tags:      gitlab, gitlab ci, i386

A thing that was not obvious to me and relatively hard to google
was a way to run a 32-bit docker image in the GitLab CI.
Docker itself has ``--platform`` param but it is not exposed to the ``.gitlab-ci.yml`` file.

Luckily it's easy for the official Docker registry.
Apart from auto-selection images, it also contains per-architecture image repos with distinct package names.
You only need to specify a desired architecture prefix: like ``amd64/php`` or ``i386/php``.

Example:

.. code-block:: yaml

    .test:
      script:
        - composer update
        - vendor/bin/phpunit

    test-64bit:
      extends: .test
      stage: test
      image: amd64/php:8

    test-32bit:
      extends: .test
      stage: test
      image: i386/php:8

or using the matrix:

.. code-block:: yaml

    test:
      stage: test
      image: ${ARCH}/php:${PHP_VERSION}
      script:
        - composer update
        - vendor/bin/phpunit
      parallel:
        matrix:
          - PHP_VERSION:
              - '7'
              - '8'
            ARCH:
              - amd64
              - i386