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

Question

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?

Answer 1

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