Docker: Connect to host from container on Linux

Dominik Rüttiger

If you’re coming from the Mac, you’re probably used to connecting to the host from inside a container with the address host.docker.internal. On Linux, however, this does not work out of the box.

Docker CLI

If you run the following command on a Linux machine, you will see that DNS resolution is not working:

Terminal window
docker run --rm alpine ping -c 1 host.docker.internal

To fix this, we need to set the DNS name manually:

Terminal window
docker run --add-host=host.docker.internal:host-gateway --rm alpine ping -c 1 host.docker.internal

Instead of host.docker.internal you could use any other name.

Docker Compose

To achieve the same result in Docker Compose, use the extra_hosts property.

Create a compose.yaml file:

compose.yaml
version: '3.9'


services:
  test:
    image: alpine
    extra_hosts:
      - 'host.docker.internal:host-gateway'

Test it with:

Terminal window
docker compose run --rm test ping -c 1 host.docker.internal

Further reading

Tags

#devops #docker #dx #linux