docker-host

Docker image to forward all traffic to the docker host

• uses dns entry host.docker.internal if available
• or default gateway as docker host

You can manually override the destination IP address by setting the environment variable DOCKER_HOST. This allows you to use this image to forward traffic to arbitrary destinations, not only the docker host.

⚠️ On Linux systems you have to bind your application to bridge network gateway in addition to localhost(127.0.0.1). Use following docker command to get the bride network gatway IP address docker network inspect bridge --format='{{( index .IPAM.Config 0).Gateway}}'

Examples

Prerequisite

Simulate localhost webserver on port 8080.

docker run --name nginx -p 8080:80 \
  -d nginx

Docker Link

Run the dockerhost container.

docker run --name 'dockerhost' \
  --cap-add=NET_ADMIN --cap-add=NET_RAW \
  --restart on-failure \
  -d qoomon/docker-host

Run your application container and link the dockerhost container. The dockerhost will be reachable through the domain/link dockerhost of the dockerhost container e.g. dockerhost:8080 This example uses curl as an application dummy.

docker run --rm \
  --link 'dockerhost' \
  appropriate/curl 'http://dockerhost:8080'

Docker Network

Create the dockerhost network.

network_name="Network-$RANDOM"
docker network create "$network_name"

Run the dockerhost container within the dockerhost network.

docker run --name "${network_name}-dockerhost" \
  --cap-add=NET_ADMIN --cap-add=NET_RAW \
  --restart on-failure \
  --net=${network_name} --network-alias 'dockerhost' \
  qoomon/docker-host

Run your application container within the dockerhost network. The dockerhost will be reachable through the domain/network-alias dockerhost of the dockerhost container e.g. dockerhost:8080 This example uses curl as an application dummy.

docker run --rm \
  --net=${network_name} \
  appropriate/curl 'http://dockerhost:8080'

Docker Compose

version: '2'

services:
    dockerhost:
        image: qoomon/docker-host
        cap_add: [ 'NET_ADMIN', 'NET_RAW' ]
        mem_limit: 8M
        restart: on-failure
    dummy:
        depends_on: [ dockerhost ]
        image: appropriate/curl
        command: ["http://dockerhost:8080"]