Question 246835 in Docker Question posted in
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how to properly "extend" a docker compose service from another project

Let’s say I have two independent/standalone docker compose projects?
At some point I realized that I also need a service from the other project
the first project looks like this:

// ./module_a/docker/docker-compose.yml
version: "3"
name: "module_a"

networks:
  module_a-network:
    driver: bridge
    external: false
services:
  module_a:
    platform: linux/amd64
    image: hello-world:latest
    networks:
      - module_a-network
  module_b:
    extends:
      file: ../module_b/docker/docker-compose.yaml
      service: module_b
    networks:
      - module_a-network

The second file looks like this:

// ./module_b/docker/docker-compose.yml
version: "3"
name: "module_b"

networks:
  module_b-network:
    driver: bridge
    external: false
services:
  module_b:
    platform: linux/amd64
    image: hello-world:latest
    networks:
      - module_b-network

when I start module_a, I get this error:

service "module_b" refers to undefined network module_b-network: invalid compose project

I can’t see what I am doing wrong, any help would be really appreciated! 🙂

I tried to add – module_a-network to the module_b service but I got a similar erro in module_b

Tags:

2

Answers


  1. 0

    Have you tried to add network b to module a like this:

    version: "3"
name: "module_a"

networks:
  module_a-network:
    driver: bridge
    external: false
  module_b-network:
    driver: bridge
    external: false
services:
  module_a:
    platform: linux/amd64
    image: hello-world:latest
    networks:
      - module_a-network
  module_b:
    extends:
      file: ../module_b/docker-compose.yml
      service: module_b
    networks:
      - module_a-network
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  2. 0

    Compose automatically creates a network named default for you. Each separate Compose project has its own default network, which is basically configured exactly the way you show the manual network configuration. Also see Networking in Compose in the Docker documentation for more details on this.

    This means you can safely delete all of the networks: blocks in both files. The containers will be automatically set to networks: [default]. Now since the default network exists in the file you’re importing into (as a different per-project default network, but that shouldn’t matter) you won’t have this conflict.

    So for example you can trim down the imported project to

    # ./module_b/docker/docker-compose.yml
version: "4.x"
name: "module_b"  # NB: not supported in Compose file version 3
services:
  module_b:
    platform: linux/amd64
    image: hello-world:latest
# NB: no networks: anywhere in this file

    then you should be able to import the file into the other project

    # ./module_a/docker/docker-compose.yml
version: "4.x"
name: "module_a"
services:
  module_a:
    platform: linux/amd64
    image: hello-world:latest
  module_b:
    extends:
      file: ../module_b/docker/docker-compose.yaml
      service: module_b

    (Also consider moving these Compose files out of directories named docker. Compose uses the innermost directory name as its default project name, so if you have two projects that both have Compose files in docker directories, Compose will think they are "the same". But a module_a/docker-compose.yml will be distinct from a module_b/docker-compose.yml. That will also let you get rid of the name: directive, and you can use the Compose file version 3 format if for some reason you still need the older Python-based Compose implementation.)

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