Merge current v2.11 into v3.1

docs/content/routing/providers/docker.md

@@ -22,7 +22,7 @@ With Docker, Traefik can leverage labels attached to a container to generate rou
 
 ## Configuration Examples
 
-??? example "Configuring Docker & Deploying / Exposing Services"
+??? example "Configuring Docker & Deploying / Exposing one Service"
 
     Enabling the docker provider
 
@@ -109,7 +109,7 @@ and the router automatically gets a rule defined by `defaultRule` (if no rule fo
 
 --8<-- "content/routing/providers/service-by-label.md"
 
-??? example "Automatic service assignment with labels"
+??? example "Automatic assignment with one Service"
 
     With labels in a compose file
 
@@ -120,7 +120,7 @@ and the router automatically gets a rule defined by `defaultRule` (if no rule fo
       - "traefik.http.services.myservice.loadbalancer.server.port=80"
     ```
 
-??? example "Automatic service creation and assignment with labels"
+??? example "Automatic service creation with one Router"
 
     With labels in a compose file
 
@@ -131,6 +131,18 @@ and the router automatically gets a rule defined by `defaultRule` (if no rule fo
       - "traefik.http.routers.myproxy.rule=Host(`example.net`)"
     ```
 
+??? example "Explicit definition with one Service"
+
+    With labels in a compose file
+
+    ```yaml
+    labels:
+      - traefik.http.routers.www-router.rule=Host(`example-a.com`)
+      # Explicit link between the router and the service
+      - traefik.http.routers.www-router.service=www-service
+      - traefik.http.services.www-service.loadbalancer.server.port=8000
+    ```
+
 ### Routers
 
 To update the configuration of the Router automatically attached to the container,
@@ -433,7 +445,7 @@ More information about available middlewares in the dedicated [middlewares secti
 
 You can declare TCP Routers and/or Services using labels.
 
-??? example "Declaring TCP Routers and Services"
+??? example "Declaring TCP Routers with one Service"
 
     ```yaml
        services:
@@ -571,7 +583,7 @@ You can declare TCP Routers and/or Services using labels.
 
 You can declare UDP Routers and/or Services using labels.
 
-??? example "Declaring UDP Routers and Services"
+??? example "Declaring UDP Routers with one Service"
 
     ```yaml
        services:

docs/content/routing/providers/swarm.md

@@ -22,7 +22,7 @@ With Docker Swarm, Traefik can leverage labels attached to a service to generate
 
 ## Configuration Examples
 
-??? example "Configuring Docker Swarm & Deploying / Exposing Services"
+??? example "Configuring Docker Swarm & Deploying / Exposing one Service"
 
     Enabling the docker provider (Swarm Mode)
 
@@ -50,7 +50,9 @@ With Docker Swarm, Traefik can leverage labels attached to a service to generate
     --providers.swarm.endpoint=tcp://127.0.0.1:2377
     ```
 
-    Attach labels to services (not to containers) while in Swarm mode (in your docker compose file)
+    Attach labels to services (not containers) while in Swarm mode (in your Docker compose file).
+    When there is only one service, and the router does not specify a service,
+    then that service is automatically assigned to the router.
 
     ```yaml
     version: "3"
@@ -67,6 +69,30 @@ With Docker Swarm, Traefik can leverage labels attached to a service to generate
         Therefore, if you use a compose file with Swarm Mode, labels should be defined in the `deploy` part of your service.
         This behavior is only enabled for docker-compose version 3+ ([Compose file reference](https://docs.docker.com/compose/compose-file/compose-file-v3/#labels-1)).
 
+??? example "Specify a Custom Port for the Container"
+
+    Forward requests for `http://example.com` to `http://<private IP of container>:12345`:
+
+    ```yaml
+    version: "3"
+    services:
+      my-container:
+        # ...
+        deploy:
+          labels:
+            - traefik.http.routers.my-container.rule=Host(`example.com`)
+            - traefik.http.routers.my-container.service=my-service"
+            # Tell Traefik to use the port 12345 to connect to `my-container`
+            - traefik.http.services.my-service.loadbalancer.server.port=12345
+    ```
+
+    !!! important "Traefik Connecting to the Wrong Port: `HTTP/502 Gateway Error`"
+        By default, Traefik uses the lowest exposed port of a container as detailed in
+        [Port Detection](../providers/swarm.md#port-detection) of the Swarm provider.
+
+        Setting the label `traefik.http.services.xxx.loadbalancer.server.port`
+        overrides this behavior.
+
 ??? example "Specifying more than one router and service per container"
 
     Forwarding requests to more than one port on a container requires referencing the service loadbalancer port definition using the service parameter on the router.
@@ -232,7 +258,7 @@ you'd add the label `traefik.http.services.<name-of-your-choice>.loadbalancer.pa
     Registers a port.
     Useful when the container exposes multiples ports.
 
-    Mandatory for Docker Swarm (see the section ["Port Detection with Docker Swarm"](../../providers/docker.md#port-detection)).
+    Mandatory for Docker Swarm (see the section ["Port Detection with Docker Swarm"](../../providers/swarm.md#port-detection)).
     {: #port }
 
     ```yaml