Documented the use of Docker with the Symfony server

Author: javiereguiluz

setup/symfony_server.rst

@@ -244,6 +244,72 @@ server provides a ``run`` command to wrap them as follows:
     # stop the web server (and all the associated commands) when you are finished
     $ symfony server:stop
 
+Docker Integration
+------------------
+
+The local Symfony server provides full `Docker`_ integration for projects that
+use it. First, make sure to expose the container ports:
+
+.. code-block:: yaml
+
+    # docker-compose.override.yaml
+    services:
+        database:
+            ports:
+                - "3306"
+
+        redis:
+            ports:
+                - "6379"
+
+        # ...
+
+Then, check your service names and update them if needed (Symfony creates
+environment variables following the name of the services so they can be
+autoconfigured):
+
+.. code-block:: yaml
+
+    # docker-compose.yaml
+    services:
+        # DATABASE_URL
+        database: ...
+        # MONGODB_DATABASE, MONGODB_SERVER
+        mongodb: ...
+        # REDIS_URL
+        redis: ...
+        # ELASTISEARCH_HOST, ELASTICSEARCH_PORT
+        elasticsearch: ...
+        # RABBITMQ_DSN
+        rabbitmq: ...
+
+If you can't or don't want to update the service names, you must remap the env
+vars so Symfony can find them. For example, if you want to keep a service called
+``mysql`` instead of renaming it to ``database``, the env var will be called
+``MYSQL_URL`` instead of the ``DATABASE_URL`` env var used in the Symfony
+application, so you add the following to the ``.env.local`` file:
+
+.. code-block:: bash
+
+    # .env.local
+    MYSQL_URL=${DATABASE_URL}
+    # ...
+
+Now you can start the containers and all their services will be exposed. Browse
+any page of your application and check the "Symfony Server" section in the web
+debug toolbar. You'll see that "Docker Compose" is "Up".
+
+SymfonyCloud Integration
+------------------------
+
+The local Symfony server provides full, but optional, integration with
+`SymfonyCloud`_, a service optimized to run your Symfony applications on the
+cloud. It provides features such as creating environments, backups/snapshots,
+and even access to a copy of the production data from your local machine to help
+debug any issues.
+
+`Read SymfonyCloud technical docs`_.
+
 Bonus Features
 --------------
 
@@ -282,18 +348,8 @@ commands from the Symfony server:
     # creates a new project based on the Symfony Demo application
     $ symfony new --demo my_project_name
 
-SymfonyCloud Integration
-------------------------
-
-The local Symfony server provides full, but optional, integration with
-`SymfonyCloud`_, a service optimized to run your Symfony applications on the
-cloud. It provides features such as creating environments, backups/snapshots,
-and even access to a copy of the production data from your local machine to help
-debug any issues.
-
-`Read SymfonyCloud technical docs`_.
-
 .. _`symfony.com/download`: https://symfony.com/download
 .. _`different ways of installing Symfony`: https://symfony.com/download
+.. _`Docker`: https://en.wikipedia.org/wiki/Docker_(software)
 .. _`SymfonyCloud`: https://symfony.com/cloud/
 .. _`Read SymfonyCloud technical docs`: https://symfony.com/doc/master/cloud/intro.html