Cannot link to a running container started by docker-compose

Question

I am setting up my local development environment with docker containers. The docker-compose.yml is like following

version: \'2\'

services:
  db:
    image:         


        

Answer 1

Ok, found the answer to it. In case anyone else comes across the same problem, just do

docker network ls

This command lists all the docker networks. docker-compose will create a new network when you run docker-compose up. In my case, the network is named as myapp_default.

Note: Your app’s network is given a name based on the “project name”, which is based on the name of the directory it lives in. You can override the project name with either the --project-name flag or the COMPOSE_PROJECT_NAME environment variable. Networking in Compose

So the correct way to link to those containers is

docker run --link my_app_mq_1:mq --link my_app_db_1:db -it --net myapp_default worker 

Answer 2

When you use service definition version 2 and more, docker-compose creates user-defined network. Name resolution in a user-defined network works via Docker embedded DNS server. Here's related quote from documentation:

The Docker embedded DNS server enables name resolution for containers connected to a given [user-defined] network. This means that any connected container can ping another container on the same network by its container name.

Containers are also available by network aliases that docker-compose creates. It can be verified by command like:

docker inspect \
  -f '{{json .NetworkSettings.Networks.myapp_default.Aliases}}' my_app_db_1

It prints ["db","$CONTAINER_ID"].

Providing links with --link will not have any effect in case of existing user-defined network. You can make sure and look at /etc/hosts, which will not have the corresponding lines.

Thus the following command is sufficient:

docker run -it --net myapp_default worker

Answer 3

my command to run links

docker run --network=YOUR_NETWORK --link SERVICE -t -i app command