Connection between docker instances

[walbertus]

Is it possible to do connections between different docker instances?
If it's there, can you point out the documentation or how-to? I can't find it anywhere

e.g:

platforms:
  - name: pg-master
    image: ubuntu:18.04
    provision: True
  - name: pg-replica
    image: ubuntu:18.04
    provision: True

I need the pg-replica to be able to connect to pg-master

If it's not supported, any clue on which part should I look when I want to raise a PR? Thanks

[1moere1]

This is really needed for many use-cases. One example is testing Active Directory Setup Roles.

[hassenius]

I've just wrestled with this same problem, and after some pointers from the folks over at IRC found the solution in this

platforms:
  - name: ${MOLECULE_SCENARIO_NAME}-pdns
    image: pdns-alpine:4.2.3
    docker_networks: 
      - name: ${MOLECULE_SCENARIO_NAME}
    publish_all_ports: true
    env:
      PDNS_LOG_LEVEL: "5"
      PDNS_WEBSERVER_ALLOWED_FROM: 0.0.0.0/0
    pre_build_image: yes
    override_command: no
  - name: ${MOLECULE_SCENARIO_NAME}-runner
    image: python:3.9-alpine-requests
    docker_networks: 
      - name: ${MOLECULE_SCENARIO_NAME}
    pre_build_image: true
    command: sleep infinity

and then I can do things like

nslookup -type=a myhost.testzone {{ groups['all'][0] }}

and

- name: Converge
  hosts: localhost
  gather_facts: no
  tasks:
    - name: "Create test zone for a records"
      community.docker.docker_container_exec:
        container: "{{ groups['all'][0] }}"

Basically since the containers are in a custom docker network they can do service discovery based on container names, etc....

[hassenius]

Be aware though that for some of the CI tests I want to do, I also want the CI container to be a part of the same network for various validations, and to support this use case I've opened #70 such that we can have molecule place the containers in existing networks where we can access the test containers from the molecule container in the same fashion, without molecule attempting to delete the network during destroy step