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How to add extra hosts to Docker containers
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If you need to add extra hosts to any of the Docker services, you can do that by adding them in the
``docker-compose.override.yml`` file, which is located in ``/home/fleio/compose``.

The following syntax should be used:

.. code-block:: yaml

    version: "3.7"
    services:
      backend:
        extra_hosts:
          - "example1:10.10.10.2"
          - "example2:10.10.10.3"
      celery:
        extra_hosts:
          - "example1:10.10.10.2"
          - "example2:10.10.10.3"
      celerybeat:
        extra_hosts:
          - "example1:10.10.10.2"
          - "example5:10.10.10.3"
      operations:
        extra_hosts:
          - "example1:10.10.10.2"
          - "example2:10.10.10.3"
      updated:
        extra_hosts:
          - "example1:10.10.10.2"
          - "example6:10.10.10.6"
      incomingmail:
        extra_hosts:
          - "example1:10.10.10.2"
      utils:
        extra_hosts:
          - "example1:10.10.10.2"

The ``utils`` container is used for commands like ``fleio bash`` or ``fleio shell``. You might need extra
hosts for debugging commands like ``ping`` or ``telnet``.

Finally, you need to run ``fleio recreate`` in order to apply the changes. Note that all Fleio containers will be re-created,
so any manual change inside Docker containers will be lost.