ci: Docker, supress supervisord warnings, start backend on 4200

var/docker/entrypoint.sh

@@ -38,4 +38,4 @@ if [[ $POSTIZ_APPS == *"backend"* ]]; then
 	ln -sf /app/supervisord_available_configs/backend.conf /etc/supervisor.d/
 fi
 
-/usr/bin/supervisord
+/usr/bin/supervisord -c /etc/supervisord.conf

var/docker/supervisord.conf

@@ -2,6 +2,7 @@
 nodaemon=true
 logfile=/dev/null
 logfile_maxbytes=0
+user=root
 
 [unix_http_server]
 file=/run/supervisord.sock

var/docker/supervisord/frontend.conf

@@ -6,3 +6,4 @@ autorestart=false
 redirect_stderr=true
 stdout_logfile=/dev/fd/1
 stdout_logfile_maxbytes=0
+environment=PORT=4200