How do I connect containers using container name with docker-compose?

Question

I am trying to understand how I access containers between each other through their container name. Specifically when using a pgadmin container and connecting to a postgresql container through dns.

In docker-compose V3 , I cannot link them, nor does networks: seem to be available either.

The main reason to need this is when the containers spin up they don't have a static IP address, so in pgadmin I can't connect to the postgresql DB using the same IP every time , so a dns name would work better (ie: the container name).

Can we do this with docker-compose or at least set a static ip address for a specific container?

I have tried creating a user defined network:

networks:
  backed:

and then using it in the service:

app:
  networks:
    - backend

This causes a docker-compose error regarding an invalid option of "networks" in the app.

docker-compose.yml

version: "0.1"

services:
  devapi:
    container_name: devapi
    restart: always
    build: .
    ports:
      - "3000:3000"

  api-postgres-pgadmin:
    container_name: api-postgres-pgadmin
    image: dpage/pgadmin4:latest
    ports:
      - "5050:80"
    environment:
      - [email protected]
      - PGADMIN_DEFAULT_PASSWORD=12345

  api-postgres:
    container_name: api-postgres
    image: postgres:10
    volumes:
      - ./data:/data/db
    ports:
      - "15432:5432"
    environment:
      - POSTGRES_PASSWORD=12345

Can you clarify this sentence more "I am trying to understand how I access containers between each other through their container name. "? Also, why can't you use the host-name to communicate between containers? — jman
– jman, Commented Apr 12, 2019 at 2:11
Also, your example docker-compose.yml doesn't show your (attempted) use of networks. Can you update it to include that? It might highlight why you're seeing that error. — larsks
– larsks, Commented Apr 12, 2019 at 2:12

larsks · Accepted Answer · 2019-04-12 02:15:12Z

2

Actually, I spot one immediate problem:

version: "0.1"

Why are you doing this? The current version of the compose file format is 3.x. E.g:

version: "3"

See e.g. the Compose file version 3 reference.

The version determines which feature are available. It's entirely possible that by setting version: "0.1" you are explicitly disabling support for the networks parameter. You'll note that the reference shows examples using the networks attribute.

As an aside, unless there is a particular reason you ened it, I would drop the use of the container_name in your compose file, since this makes it impossible to run multiple instances of the same compose file on your host.

answered Apr 12, 2019 at 2:15

larsks

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Sreenivasa Reddy · Accepted Answer · 2019-04-12 02:24:43Z

0

networks are available from docker-compose version 3 but you are using version:"0.1" in your docker-compose file.

Change the version: "0.1" to version: "3" in docker-compose.yml.

answered Apr 12, 2019 at 2:24

Sreenivasa Reddy

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