disable built in redis if env set

docker/init_scripts/init

@@ -107,7 +107,10 @@ cd /backend || { error_log "/backend directory doesn't seem to exist"; }
 # function definition done, lets start our main loop
 while true; do
     # Start redis server if we dont have a corresponding PID file
-    watchdog_process_pid bin redis-server
+    # and REDIS_HOST is not set (which would mean we're using an external redis)
+    if [[ -z "${REDIS_HOST}" ]]; then
+        watchdog_process_pid bin redis-server
+    fi
 
     # Run needed database migrations on startup,
     # but only if it was not successful since the last full docker container start