Fix 502 gateway error

docker-compose.yml

@@ -6,9 +6,9 @@ db:
     - /etc/localtime:/etc/localtime:ro
   # uncomment the following to enable backup
   environment:
-    - MM_USERNAME=mattermost_user
+    - MM_USERNAME=mmuser
-    - MM_PASSWORD=mattermost_password
+    - MM_PASSWORD=mmuser_password
-    - MM_DBNAME=mattermost_db
+    - MM_DBNAME=mattermost
   #  - AWS_ACCESS_KEY_ID=XXXX
   #  - AWS_SECRET_ACCESS_KEY=XXXX
   #  - WALE_S3_PREFIX=s3://BUCKET_NAME/PATH