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ankitkamboj
ankitkamboj

Reputation: 541

Docker Compose V2 network error

I am trying to communicate between two containers, but unable to do the same. I add a service named 'server' in docker compose dependent on another service named 'endpoint'. I am need to pass the ip and port of 'endpoint' to 'server', and i am doing the same as below 

command: -userver -e endpoint:51393

But now on i don't see 'endpoint' in the list of hosts using below command:

docker-compose exec server cat /etc/hosts

Here is output:

127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
172.21.0.3      49f4808fa677

My Full docker-compose.yml file is as below:

version: '2'

services:
  endpoint:
    build:
      context: .
      dockerfile: Dockerfile
    image: myimage_end:0.1
    command: -uendpoint
    ports:
      - 51393:51393
    networks:
      - internal

  server:
    build:
      context: .
      dockerfile: Dockerfile
    image: myimage_server:0.1
    command: -userver -e endpoint:51393
    ports:
      - 51392:51392
    depends_on:
      - endpoint
    networks:
      - internal
    volumes:
      - /local_path/dataset:/dataset

networks:
  internal:
    driver: bridge

Upvotes: 0

Views: 577

Answers (1)

Andreas Jägle
Andreas Jägle

Reputation: 12240

When you use a current version of docker compose, reaching one container from another is no longer done by manipulating a container's hosts file, because this is a pretty static setup.

Nowadays docker-compose uses some kind of dns service that allows all containers in the same network to see each other under their service names. This allows dependent containers to be stopped without causing a depending container to also stop/restart. For this to work, you also don't need to specify depends_on. This is only required to trigger a restart of the depending service when a dependency is restarted.

For more details, please have a look at the docker-compose docs about networking.

Some commands for debugging your situation:

docker-compose exec server nslookup endpoint

docker inspect <container_name_of_service>

Upvotes: 2

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