# Services Drone uses the `compose` section of the `.drone.yml` to specify supporting containers (ie service containers) that should be started and linked to your build container. The `compose` section of the `.drone.yml` is modeled after `docker-compose`: ``` compose: [container_name:] image: [image_name] [options] ``` Example configuration that composes a Postgres and Redis container: ```yaml compose: cache: image: redis database: image: postgres environment: - POSTGRES_USER=postgres - POSTGRES_PASSWORD=mysecretpassword ``` ## Service networking Service containers are available at the `localhost` or `127.0.0.1` address. Drone deviates from the default Docker compose networking model to mirror a traditional development environment, where services are typically accessed at `localhost` or `127.0.0.1`. To achieve this, we create a per-build network where all containers share the same network. ## Service options The service container configuration options: * `image` - any valid Docker image name * `pull` - if true, will always attempt to pull the latest image * `environment` - list of environment variables, declared in `name=value` format * `privileged` - if true, runs the container with extended privileges [1] * `volumes` - list of bind mounted volumes on the host machine [1] * `net` - sets the container [network mode](https://docs.docker.com/articles/networking/#container-networking) [1] [1] Some build options are disabled for security reasons, including `volumes`, `privileged` and `net`. To enable these options, a system administrator must white-list your repository as trusted. This can be done via the repository settings screen.