# TeamCity docker-compose: build agents not found (serverUrl points at YOUR_HOST)
## The problem
After starting TeamCity with the JetBrains docker-compose sample, no build agents appeared in the server UI even though the agent containers were running fine. The default buildAgent.properties points the agent at http://YOUR_HOST:8111, so each agent tried to reach a TeamCity server on itself instead of the actual server container. Changing the URL to the host IP or the published port did not help either.
## The verified fix
Inside the compose bridge network, agents must address the server by its service alias and internal port, not YOUR_HOST or the host's published port. In each agent's buildAgent.properties set serverUrl=http://teamcity:8111 (backslash-escaped per the properties format: http\://teamcity\:8111), keep the server's internal port 8111, and leave the 8112:8111 host mapping for browser access. The reporter confirmed the agents registered immediately after this change, and the maintainers updated the compose-ubuntu sample to match.
Source: https://github.com/JetBrains/teamcity-docker-samples/issues/4