resolve host machine hostname inside docker container-CodePudding

I have one application running on http://home.local:8180 in container A. And the other container B is running on http://data.local:9010. Container B is using container A to hit the API. If I specify container A hostname as http://host.docker.internal:8180 in container B then it works. What I would have to do if I want to use the hostname as is (home.local:8180) Following is the docker-compose file:

  home_app:
    hostname: "home.local"
    image: "home-app"
    ports:
    - "8180:8080"
    environment:

  data_app:
    hostname: "data.local"
    image: "data-app"
    links:
      - "home_app"
    ports:
    - "9010:9010"

CodePudding user response：

Just use "home.local:8080". 8180 is just on the host machine and forwards to 8080 on the container, whereas based on your docker-compose, 8080 is the port of your application on home_app container, so within the docker-compose network, other containers should be able to access it via hostname (home.local) and the actual ports (8080).

CodePudding user response：

You need to configure your application to use the Compose service name home_app as a host name, and the port number that the process inside the container is using. Neither hostname: nor ports: has any effect on connections between containers. You don't need to (and can't) specify a custom DNS suffix. See Networking in Compose in the Docker documentation for additional details.

So I might specify:

version: '3.8'
services:
  home_app:
    image: "home-app"
    ports:
    - "8180:8080" # optional, only for access from outside Docker

  data_app:
    image: "data-app"
    ports:
    - "9010:9010"
    environment:
      HOME_APP_URL: 'http://home_app:8080'

You don't need hostname:, which only affects what a container thinks its own hostname is and has no effect on anything outside the container; and you don't need links:, which is an obsolete option from first-generation Docker networking.