Merge duplicate page and add note about docker networking

Traefik-Global-configuration.md

@@ -1,22 +1,54 @@
-Traefik is a reverse proxy software which sits in front of all running services on a server. It:
+Traefik is a reverse proxy software which sits in front of all running services on a server. It integrates very nicely with docker and other orchestration tools. It looks at Docker container labels to determine routing rules, middleware definitions, and other configuraiton, meaning application-specific configuration can be kept together with the application and easily applied to any server which has a Traefik reverse proxy running, rather than tying it to a particular server's global configuration. It:
 
  - [listens on port 80](https://git.tams.tech/TWS/traefik-config/src/commit/d4f6eb139c3a4f60d94bb5aa712d2a96becda7ac/traefik.yaml#L2-L4), and [redirects any requests to https on port 443](https://git.tams.tech/TWS/traefik-config/src/commit/d4f6eb139c3a4f60d94bb5aa712d2a96becda7ac/docker-compose.yml#L26-L30)
  - [listens on port 443](https://git.tams.tech/TWS/traefik-config/src/commit/d4f6eb139c3a4f60d94bb5aa712d2a96becda7ac/traefik.yaml#L5-L6) and either forwards that request to a configured service, or responds with a 404 if no matching service is configured
  - [watches a static configuration file](https://git.tams.tech/TWS/traefik-config/src/commit/d4f6eb139c3a4f60d94bb5aa712d2a96becda7ac/traefik.yaml#L30-L31) for routing rules.
- - [watches the docker service](https://git.tams.tech/TWS/traefik-config/src/commit/d4f6eb139c3a4f60d94bb5aa712d2a96becda7ac/traefik.yaml#L26-L29) for routing rules configured through labels on containers. This allows us to keep the configuration for a service with the service, rather than tying it to a particular server's global configuration.
+ - [watches the docker service](https://git.tams.tech/TWS/traefik-config/src/commit/d4f6eb139c3a4f60d94bb5aa712d2a96becda7ac/traefik.yaml#L26-L29) for routing rules configured through labels on containers.
  - [Automatically acquires certificates](https://git.tams.tech/TWS/traefik-config/src/commit/d4f6eb139c3a4f60d94bb5aa712d2a96becda7ac/traefik.yaml#L11-L23) for the configured services, either through HTTP or DNS (TXT record) validation.
 
 To deploy services on a new server, see the instructions in the README for the [traefik config repository](https://git.tams.tech/TWS/traefik-config)
 
-To add a service to a server which uses Traefik as a reverse proxy, add labels to the container like
+To add a service to a server which uses Traefik as a reverse proxy, ensure it is in the `web` network and add labels to the container like this:
 
 ```yaml
 services:
-  some service:
+  web-service:
-    ...
+    # This service has some public-facing HTTP service listening on port 1312
+    labels:
+      traefik.http.routers.{SERVICE_NAME}.rule: Host(`example.com`) || Host(`example.net`) && !PathPrefix(`/service/prefix`)
+      # You don't need to specify the port like this unless the container has multiple exposed ports. This is just an example:
+      traefik.http.services.{SERVICE_NAME}.loadbalancer.server.port: 1312
+      traefik.http.routers.{SERVICE_NAME}.tls: true
+      traefik.http.routers.{SERVICE_NAME}.tls.certresolver: letsencrypt
+    networks:
+      - internal
+      - web
+  database:
+    # This is something the web-service depends on, but that shouldn't be publicly exposed
+    networks: [ internal ]
+
+networks:
+  web:
+    external: true
+  internal:
+    internal: true
+```
+
+If the service stands on its own and doesn't require a dependent service, you don't need the extra internal network, but it still needs to be on the external network named `web`:
+
+```yaml
+services:
+  web-service:
     labels:
       traefik.http.routers.{SERVICE_NAME}.rule: Host(`example.com`) || Host(`example.net`) && !PathPrefix(`/service/prefix`)
       traefik.http.routers.{SERVICE_NAME}.tls: true
       traefik.http.routers.{SERVICE_NAME}.tls.certresolver: letsencrypt
+    networks: [ web ]
+
+networks:
+  web:
+    external: true
+
 ```
+
 Of course, don't forget to point the configured host's DNS records at the server you're working with!