CODEWITHSUNDEEP
dockerdocker-composedockerfiledocker-machine
The Great
The Great

Reputation: 7743

How to make Network_Mode : "host" work in docker-compose.yml file

I am trying to execute a "docker-compose up" command. Please find below my docker-compose file. I tried with network_mode: "host" but it doesn't work. I am on Linux OS. request you to let me know if I am making any blunder.

version: '3.6'
services:
   mongo:
      image: "mongo:latest"
      container_name: ohif-mongo
       ports:
         - "27017:27017"

   viewer:
      image: ohif/viewer:latest
      container_name: ohif-viewer
      ports:
        - "3030:80"
      network_mode: "host"   # please make note of the alignment
      links:
         - mongo
      environment:
         - MONGO_URL=mongodb://mongo:27017/ohif
      extra_hosts:
         - "pacsIP:172.xx.xxx.xxx"
      volumes:
         - ./dockersupport-app.json:/app/app.json

after execution, I get the below error

ERROR: for 8f4c3de7e3a3_ohif-viewer  Cannot create container for service viewer: conflicting options: host type networking can't be used with links. This would result in undefined behavior
 ERROR: for viewer  Cannot create container for service viewer: conflicting options: host type networking can't be used with links. This would result in undefined behavior

I don't know why the error message is displayed twice. Not sure whether this is expected

Second, when I change the alignment of network_mode: "host" (by 1/2 spaces)

  ports:
        - "3030:80"
        network_mode: "host"   # please see the change in alignment now
      links:
         - mongo

I get the below error message

ERROR: yaml.parser.ParserError: while parsing a block mapping
 in "./docker-compose.yml", line 10, column 5
expected <block end>, but found '<block mapping start>'
 in "./docker-compose.yml", line 14, column 6

How can I start the container with network=host mode?

Upvotes: 40

Views: 171414

Answers (3)

Nycki
Nycki

Reputation: 970

A container can't be on both the host network and the bridge network, not by using links, nor by any other combination of properties. You have to explicitly pass traffic between the host and the internal bridge network.

To get from the host to the internal network, the host network can access ports exposed by internal containers. So, for instance, note the use of 'localhost' here:

services:
  mongo:
    image: "mongo:latest"
    ports:
      - "27017:27017"
  viewer:
    image: ohif/viewer:latest
    network_mode: host
    environment:
        MONGO_URL: mongodb://localhost:27017/ohif
    # no links required

To go the other direction, from internal to host, you have to make use of the 'host-gateway' special property.

services:
  proxy-app:
    image: proxy-app
    network_mode: host
  service-app:
    image: service-app
    extra_hosts:
      - proxy-host:host-gateway
    environment:
      PROXY_URL: http://proxy-host

Upvotes: 5

joekrom
joekrom

Reputation: 396

network_mode: host is used for sharing the same networking space with the Host. For example you can want to access an application that is running on your Linux PC from the container. If you want to link services together, you can use links, or depends_on, and if the services are on different hosts just create an overlay network

Upvotes: 33

k-lusine
k-lusine

Reputation: 467

From docs:

network_mode: "host" cannot be mixed with links.

And about links

Warning: The --link flag is a legacy feature of Docker. It may eventually be removed. Unless you absolutely need to continue using it, we recommend that you use user-defined networks to facilitate communication between two containers instead of using --link. One feature that user-defined networks do not support that you can do with --link is sharing environmental variables between containers. However, you can use other mechanisms such as volumes to share environment variables between containers in a more controlled way.

Just remove the links. They are no longer required.

Upvotes: 9

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