new: [mattermost] charm handles itself the websocket when in relation with apache

mattermost/metadata.yml

@@ -1,5 +1,5 @@
-# description: "Mattermost"
-# maintainer: "Valentin Lab <valentin.lab@kalysto.org>"
+description: "Mattermost"
+maintainer: "Valentin Lab <valentin.lab@kalysto.org>"
 ## We fix image here to be sure of what we install
 docker-image: docker.0k.io/mattermost-team
 # docker-image: docker.0k.io/mattermost-enterprise
@@ -13,4 +13,32 @@ host-resources:
   - /etc/localtime:ro
 
 docker-compose:
-  restart: unless-stopped
+  restart: unless-stopped
+
+uses:
+  postgres-database:
+    constraint: required
+    auto: pair
+    solves:
+      database: "main storage"
+  log-rotate:
+    constraint: recommended
+    auto: pair
+    solves:
+      disk-leak: "/mattermost/logs"
+  web-proxy:
+    constraint: recommended
+    auto: pair
+    solves:
+      proxy: "Public access"
+    default-options:
+      apache-custom-rules:
+        - !var-expand |
+          ProxyPreserveHost On
+
+          # Set web sockets
+          RewriteEngine On
+          RewriteCond %{REQUEST_URI} /api/v[0-9]+/(users/)?websocket [NC,OR]
+          RewriteCond %{HTTP:UPGRADE} ^WebSocket$ [NC,OR]
+          RewriteCond %{HTTP:CONNECTION} ^Upgrade$ [NC]
+          RewriteRule .* ws://${MASTER_BASE_SERVICE_NAME}:8000%{REQUEST_URI} [P,QSA,L]