The runner is in a docker network. A service on that network has a domain. The runner fails making a DNS query for that alias that exposed. It works from another container so its something in docker-drone-runner. I can’t get a shell in the terminal either so i can’t test.
@more-pepsi what service? what is your configuration? when you test from other containers, are they using the default bridge network or a user-defined network (docker dns works differently depending on which you are using). It may not be clear to our readers what you are trying to achieve.
I recommend taking a look at How to Ask for Help and providing more information; without more information you may find difficulty getting your questions answered.
The runner spawns a container witch creates a random docker network. You may need to specify what network the containers should use. You can use the - DRONE_RUNNER_NETWORKS environmental variable under the docker-runner config in your compose.
Be aware that docker-compose reads networks in dict order. So if you need to use the gateway on your external network the name of the network needs to start with something thats before “d” in the alphabet. or else the gateway on the random docker network will be used as the drone-runner creates all networks starting with drone like: drone-EQg2DhwyOXHsDn1A3c8U