chore: use env vars for gluetun

examples/arr-suite/docker-compose.yml

@@ -181,11 +181,11 @@ services:
     environment:
       # see https://github.com/qdm12/gluetun-wiki for more details
       # example envs based on https://github.com/qdm12/gluetun-wiki/blob/main/setup/providers/mullvad.md
-      - VPN_SERVICE_PROVIDER=mullvad # define the vpn provider
-      - VPN_TYPE=wireguard # define the vpn protocol to use
-      - WIREGUARD_PRIVATE_KEY=wOEI9rqqbDwnN8/Bpp22sVz48T71vJ4fYmFWujulwUU= # define your wireguard private key here
-      - WIREGUARD_ADDRESSES=10.64.222.21/32 # define the ipv4 vpn network subnet here
-      - SERVER_CITIES=Paris # define the server cities
+      - VPN_SERVICE_PROVIDER=${VPN_SERVICE_PROVIDER:?VPN_SERVICE_PROVIDER must be set} # define the vpn provider
+      - VPN_TYPE=${VPN_TYPE:?VPN_TYPE must be set} # define the vpn protocol to use
+      - WIREGUARD_PRIVATE_KEY=${WIREGUARD_PRIVATE_KEY:?WIREGUARD_PRIVATE_KEY must be set} # define your wireguard private key here
+      - WIREGUARD_ADDRESSES=${WIREGUARD_ADDRESSES:?WIREGUARD_ADDRESSES must be set} # define the ipv4 vpn network subnet here
+      - SERVER_CITIES=${SERVER_CITIES:?SERVER_CITIES must be set} # define the server cities
     volumes:
       - ${DOCKER_VOLUME_STORAGE:-/mnt/docker-volumes}/arr-suite/configs/gluetun:/gluetun
     restart: unless-stopped