How can I add hostnames to a container on the same docker network?

Question

Suppose I have a docker compose file with two containers. Both reference each other in their /etc/hosts file. Container A has a reference for container B and vice versa. And all of this happens automatically. Now I want to add one or more hostnames to B in A's hosts file. How can I go about doing this? Is there a special way I can achieve this in Docker Compose?

Example:

172.0.10.166 service-b my-custom-hostname

Answer 1

Yes. In your compose file, you can specify network aliases.

services:
  db:
    networks:
      default:
        aliases:
          - database
          - postgres

In this example, the db service could be reached by other containers on the default network using db, database, or postgres.

You can also add aliases to running containers using the docker network connect command with the --alias= option.