Django can't translate "postgres" name for postrgres database

[rllola]

I usually use the name of my docker-compose service inside my django application to connect to the database (postgres) but when I use the reverse proxy on the Django service it says it can't translate 'postgres' to a hostname :

could not translate host name "postgres" to address: Name or service not known

Usually docker-compose is able to do it.
Do you have any idea why it doesn't work when using the reverse-proxy and how I could fix it ?

[nknapp]

I don't know if you still need the answer to your problem. I feel a little sad that I hadn't written even a short notice because I actually would like to help people. But without investigating further I would not have had an answer to your question. But...

I just came across the same problem and I found out why it happened. In short: You have to configure the networks correctly in your docker-compose-file.

You can use the ghost-mysql-repo as an example:

• These lines in the docker-compose file make sure that the web-server is in the same network as the reverse-proxy and in the same network as the database
• These lines in the docker-compose file put the database in its network.
• These lines create the networks that are used in the other lines.

If the network is only defined for the webserver, it will not be in the default-network for the compose-file anymore, but the database will still be. So the webserver will not know about the database.

[jaceee]

For future reference:

When you specify the traefik network you're letting the container out of the default network, just add it to the networks too.

Example:

version: '3.1'

services:
  cache:
    restart: always
    image: redis:latest

  db:
    restart: always
    image: postgres:latest

  backend:
    restart: always
    image: whatever:latest
    links:
      - cache
      - db
    networks:
      - default # default network to be able to access cache and db
      - traefik
    labels:
      - "traefik.port=80"
      - "traefik.frontend.rule=Host:api.yggdrasil.dev"
      - "traefik.docker.network=traefik_default" # telling traefik which network to use to reach the container

networks:
  traefik:
    external:
      name: traefik_default

[nknapp]

"For future reference" sounds like this should be an example in the README.md.
Who's up for a PR?