Adding docker compose override files to cob docker deploy

cob/cli/docker_cli.py

@@ -411,19 +411,27 @@ def _generate_compose_file_from_image(image_name, *, http_port=None):
 
 @docker.command(name='deploy', help='Deploys an dockerized cob app image to the local systemd-based machine')
 @click.option('--force', is_flag=True, default=False)
+@click.option('--compose-override', 'compose_overrides', multiple=True)
 @click.argument('image_name')
-def deploy_image(image_name, force):
+def deploy_image(image_name, force, compose_overrides):
     click.echo(f'Obtaining project information for {image_name}...')
     project_name = _get_project_name_from_image(image_name)
     unit_template = load_template('systemd_unit')
     filename = Path('/etc/systemd/system') / f'{project_name}-docker.service'
+
+    for override_file in compose_overrides:
+        docker_compose_override_file = Path(override_file)
+        _logger.debug(f'Checking the existance of a docker compose override file under project root {docker_compose_override_file}')
+        if not docker_compose_override_file.exists():
+            raise click.ClickException(f'File {docker_compose_override_file} does not exist')
+
     click.echo(f'Writing systemd unit file under {filename}...')
     if filename.exists() and not force:
         click.confirm(f'{filename} already exists. Overwrite?', abort=True)
 
     tmp_filename = Path(mkdtemp()) / 'systemd-unit'
     with tmp_filename.open('w') as f: # pylint: disable=no-member
-        f.write(unit_template.render(project_name=project_name, image_name=image_name, cob=f'{sys.executable} -m cob.cli.main'))
+        f.write(unit_template.render(project_name=project_name, image_name=image_name, compose_overrides=compose_overrides, cob=f'{sys.executable} -m cob.cli.main'))
 
     subprocess.check_call(f'sudo -p "Enter password to deploy service" mv {tmp_filename} {filename}', shell=True)
     click.echo(f'Starting systemd service {filename.stem}...')

cob/templates/systemd_unit.j2

@@ -7,7 +7,7 @@ After=docker.service
 Type=oneshot
 RemainAfterExit=yes
 ExecStartPre=-{{cob}} docker stop-image {{image_name}}
-ExecStart={{cob}} docker run-image {{image_name}} -d
+ExecStart={{cob}} docker run-image {{image_name}} {% for cfile in compose_overrides %} -o {{cfile}} {% endfor %} -d
 ExecStop={{cob}} docker stop-image {{image_name}}
 
 [Install]

doc/deployment.rst

@@ -87,3 +87,10 @@ If your target machine is based on *systemd* (e.g. recent Ubuntu Server releases
   $ cob docker deploy your.server.com:4567/myproject:latest
 
 This will pull off the needed information from the Docker image and create appropriate unit files to run your project.
+
+
+
+.. note:: cob uses docker-compose for deployment. a docker-compose-override yml file can be provided which is then used as described in `docker-compose overview <https://docs.docker.com/compose/reference/overview/>`_.
+
+To use the above capability, add ``--compose-override <full path to override file>`` to the above ``cob docker deploy`` command.
+You can use more than one compose-override files by repeating the flag for each file.