What is linux equivalent of “host.docker.internal”

Question

On Mac and Windows it is possible to use docker.for.mac.host.internal (replaces docker.for.mac.localhost) and docker.for.win.host.int

Answer 1

Depends what you're trying to do. If you're running with --net=host, localhost should work fine. If you're using default networking, use the static IP 172.17.0.1. I suspect neither will behave quite the same as those domains.

Answer 2

Using the docker0 interface ip, say 172.17.0.1, could be a good workaround.

Just be sure that the service you need to reach listens to external connections. A typical example is Mysql who binds to 127.0.0.1 by default, resulting unreachable until you allow external connections (es. binding to 0.0.0.0)

Answer 3

One solution is to use a special container which redirects traffic to the host. You can find such a container here: https://github.com/qoomon/docker-host. The idea is to grab the default route from within the container and install that as a NAT gateway for incoming connections.

An imaginary example usage:

docker-host:
  image: qoomon/docker-host
  cap_add: [ 'NET_ADMIN', 'NET_RAW' ]
  restart: on-failure
  environment:
    - PORTS=999

some-service:
  image: ...
  environment:
    SERVER_URL: "http://docker-host:999"
  command: ...
  depends_on:
    - docker-host