Docker compose network issue

General
,
1

I have the following docker-compose.yml file:

version: "3.9"
services:
    result:
        image: result
        ports:
            - "8080:80"
        networks:
            - test-wp-network

And network:

docker network list  | grep test
a18a8c7a2764   test-wp-network   bridge    local

But when I run docker-compose up the following error is shown:

service "db" refers to undefined network test-wp-network: invalid compose project

Could you please clarify what is the issue and how it can be fixed?

For example, if I run it as below:

docker run --name=db -e POSTGRES_PASSWORD=mysecretpassword --network=test-wp-network postgres:9.4

It is working fine

2

I guess I found the solution it should be as below:

version: "3.9"
services:
    db:
        image: postgres:9.4
        environment:
            - POSTGRES_HOST_AUTH_METHOD=trust
        networks:
            - test-wp-network
    result:
        image: result
        ports:
            - "8080:80"
        networks:
            - test-wp-network
networks:
    test-wp-network:

With the declared network

3

Yes, you need the definition of the network in the compose file, but docker compose will create an other network with the project name as prefix like: <projectname>_<networkname>. For example: myproject_test-wp-network. It’s fine and usually a good idea, but if you want to use the same network that you created without compose, that is an “external network”: Docker Compose documentation: external network