Merge branch '5.1' into 5.x

* 5.1:
  Add a mention to COMPOSE_FILE and COMPOSE_PROJECT_NAME vars

Author: javiereguiluz

setup/symfony_server.rst

@@ -361,6 +361,23 @@ When Docker services are running, browse a page of your Symfony application and
 check the "Symfony Server" section in the web debug toolbar; you'll see that
 "Docker Compose" is "Up".
 
+If your Docker Compose file is not at the root of the project, use the
+``COMPOSE_FILE`` and ``COMPOSE_PROJECT_NAME`` environment variables to define
+its location, same as for ``docker-compose``:
+
+.. code-block:: bash
+
+    # start your containers:
+    COMPOSE_FILE=docker/docker-compose.yaml COMPOSE_PROJECT_NAME=project_name docker-compose up -d
+
+    # run any Symfony CLI command:
+    COMPOSE_FILE=docker/docker-compose.yaml COMPOSE_PROJECT_NAME=project_name symfony var:export
+
+.. note::
+
+    If you have more than one docker-compose files you can provide them all
+    separated by ``:``, as explained in the `Docker compose CLI env var reference`_.
+
 SymfonyCloud Integration
 ------------------------
 
@@ -381,3 +398,4 @@ debug any issues.
 .. _`Proxy settings in macOS`: https://support.apple.com/guide/mac-help/enter-proxy-server-settings-on-mac-mchlp2591/mac
 .. _`Proxy settings in Ubuntu`: https://help.ubuntu.com/stable/ubuntu-help/net-proxy.html.en
 .. _`is treated differently`: https://ec.haxx.se/usingcurl/usingcurl-proxies#http_proxy-in-lower-case-only
+.. _`Docker compose CLI env var reference`: https://docs.docker.com/compose/reference/envvars/