CODEWITHSUNDEEP
docker-composedocker-network
makozaki
makozaki

Reputation: 4366

Network visibility within docker-compose

I have built a docker-compose with 3 services: db, nginx, selenium. App hosted with nginx communicates with database (nginx <-> db), and selenium tests app (selenium -> app).

version: '3'
services:
  nginx:
    image: <my_private_repo>/nginx
    ...
  db:
    image: <my_private_repo>/db
    # nginx cannot communicate with db after I remove exposing port 3306
    ports:
      - "3306:3306"
    ...
  selenium:
    image: joyzoursky/python-chromedriver:3.8-selenium
    command: "bash seleniumScript.sh"
    depends_on:
      - nginx
      - db

I run my tests with docker-compose run selenium Everything works when I expose database port but when I stop exposing port 3306 nginx is unable to communicate with db.

My understanding was that all services within one docker-compose setup are automatically connected and user doesn't need to create any additional networks but I was obviously wrong.

My question is how should I setup exposing ports between services without exposing them to host machine?

Update: My nginx app has configured database host to service name db. Selenium script setup fill database using db host and tests nginx app via https://nginx url.

Upvotes: 0

Views: 1152

Answers (1)

Tom
Tom

Reputation: 4682

This question here asks something very similar.

The nginx container cannot reach the database container probably, because you're accessing it via docker host localhost.

Containers that are in the same network can always reach each other without exposing any ports, but using hostnames. See: the docker docs. That means, that you can connect to the database container from inside the nginx container using db:3306.

Compose by default creates a default network for the project, so unless you want to prevent some containers from being able to communicate with each other, you won't have to create any new networks.

Upvotes: 1

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