allow removing something in docker-compose.override.yml
Problem
My usecase is that the base `docker-compose.yml` maps a certain port in the `ports` section. In my `docker-compose.override.yml` I'd like to change that port since I already have a different service running there on my host. As far as I understand the current implementation it is only possible to add stuff, override extends the other file. As far as I can tell there is no way to remove an entry. And I can't think of an obvious syntax for it.
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1 Fix
Override Docker Compose Port Mapping Using Environment Variables
Docker Compose does not support removing or overriding specific entries in the `ports` section of a service defined in `docker-compose.yml` through `docker-compose.override.yml`. The override file is designed to extend configurations rather than remove them, leading to conflicts when the same port is already in use on the host.
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Define Environment Variable for Port
In your `docker-compose.override.yml`, define an environment variable for the port you want to use. This allows you to dynamically set the port without directly modifying the base configuration.
yamlversion: '3' services: your_service: environment: - SERVICE_PORT=8081 - 2
Modify Dockerfile to Use Environment Variable
Ensure that your Dockerfile or application code uses the `SERVICE_PORT` environment variable to set the listening port. This way, it will adapt to the port defined in the override file.
dockerfileEXPOSE ${SERVICE_PORT} CMD ["your_command", "--port", "${SERVICE_PORT}"] - 3
Update Ports Mapping in docker-compose.override.yml
In the `docker-compose.override.yml`, map the service to the environment variable instead of a static port number. This will allow you to change the port without conflicts.
yamlversion: '3' services: your_service: ports: - "${SERVICE_PORT}:${SERVICE_PORT}" - 4
Run Docker Compose
Execute `docker-compose up` to start your services with the new port mapping. Ensure that the environment variable is set correctly before running the command.
bashSERVICE_PORT=8081 docker-compose up
Validation
Check that the service is running on the new port by accessing it via `http://localhost:8081` (or the port you set). You can also run `docker ps` to verify that the container is mapped to the correct port on the host.
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Submitted by
Alex Chen
2450 rep