Local instance of drone.io cannot authenticate with local gitea using treafik subdomains. Dial tcp: lookup no such host

Question

I tired to setup local instance of of gitea and drone.io using docker-compose.

I use traefik routing for custom local subdomains .docker.localdev, dnsmasq and locally-trusted certificates with mkcert as described in this article: https://medium.com/soulweb-academy/docker-local-dev-stack-with-traefik-https-dnsmasq-locally-trusted-certificate-for-ubuntu-20-04-5f036c9af83d

I added OAuth2 application in gitea and added redirect URI https://droneio.docker.localdev/login. Client ID & Client Secret added to docker-compose.yaml.

When i authenticate Drone it results in error after final redirection:

Login Failed. Post "https://gitea.docker.localdev/login/oauth/access_token": dial tcp: lookup gitea.docker.localdev on 127.0.0.11:53: no such host

I only managed to get working setup using private LAN addresses with ports instead of treafik subdomains.

How to configure docker to make treafik subdomains accessible between these containers?

My current docker-compose.yaml:

---
version: '3'
services:
  gitea:
    image: gitea/gitea
    environment:
      - SSH_DOMAIN=gitea.docker.localdev
      - SSH_PORT=222
      - SSH_LISTEN_PORT=22
      - ROOT_URL=gitea.docker.localdev

    volumes:
      - ./gitea_data:/data
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.gitea-web.entrypoints=web"
      - "traefik.http.routers.gitea-web.rule=Host(`gitea.docker.localdev`)"
      - "traefik.http.routers.gitea-web.service=gitea-web-svc"
      - "traefik.http.services.gitea-web-svc.loadbalancer.server.port=3000"
      - traefik.http.routers.gitea-http.middlewares=gitea-https
      - traefik.http.middlewares.gitea-https.redirectscheme.scheme=https
      - traefik.http.routers.gitea-https.entrypoints=websecure
      - traefik.http.routers.gitea-https.rule=Host(`gitea.docker.localdev`)
      - traefik.http.routers.gitea-https.tls=true
      - "traefik.tcp.routers.gitea-ssh.rule=HostSNI(`*`)"
      - "traefik.tcp.routers.gitea-ssh.entrypoints=ssh"
      - "traefik.tcp.routers.gitea-ssh.service=gitea-ssh-svc"
      - "traefik.tcp.services.gitea-ssh-svc.loadbalancer.server.port=22"
    networks:
      - web

  droneio:
    image: drone/drone:latest
    container_name: droneio
    restart: unless-stopped
    volumes:
      - /etc/localtime:/etc/localtime:ro
      - /etc/timezone:/etc/timezone:ro
      - /var/docker/droneio-data:/data
    environment:
      - DRONE_SERVER_HOST=droneio.docker.localdev
      - DRONE_SERVER_PROTO=https
      - DRONE_RPC_SECRET=4810ef8120663ffa960dfa1d78c5d437
      # Gitea Config
      - DRONE_GITEA_SERVER=https://gitea.docker.localdev/
      - DRONE_GITEA_CLIENT_ID=0828a8c9-02f5-459e-9804-8b37ea0b3eb7
      - DRONE_GITEA_CLIENT_SECRET=gto_p6pydy3m5j6jetbcyz6oqzoslrpil7evsi7xbx5xgwngxywn6scq
      - DRONE_LOGS_PRETTY=true
      - DRONE_LOGS_COLOR=true
      - DRONE_DEBUG=true
      - DRONE_TRACE=true
    labels:
      - traefik.enable=true
      - traefik.http.routers.droneio-http.entrypoints=web
      - traefik.http.routers.droneio-http.rule=Host(`droneio.docker.localdev`)
      - traefik.http.routers.droneio-http.middlewares=droneio-https
      - traefik.http.middlewares.droneio-https.redirectscheme.scheme=https
      - traefik.http.routers.droneio-https.entrypoints=websecure
      - traefik.http.routers.droneio-https.rule=Host(`droneio.docker.localdev`)
      - traefik.http.routers.droneio-https.tls=true
    networks:
      - web
    depends_on:
      - gitea
  drone-runner:
    image: drone/drone-runner-docker:1
    container_name: drone-runner
    restart: unless-stopped
    volumes:
      - /etc/localtime:/etc/localtime:ro
      - /etc/timezone:/etc/timezone:ro
      - /var/run/docker.sock:/var/run/docker.sock
    environment:
      - DRONE_RPC_PROTO=https
      - DRONE_RPC_HOST=droneio.docker.localdev
      - DRONE_RPC_SECRET=4810ef8120663ffa960dfa1d78c5d437 #  random string generated by openssl rand -hex 16
      - DRONE_RUNNER_CAPACITY=2
      - DRONE_RUNNER_NAME=droneio.docker.localdev
    ports:
      - 3500:3000
    depends_on:
      - droneio

networks:
  web:
    external: true
volumes:
  git:
  db:

Answer 1

The drone container has no way to be aware of what is happening in the gitea container. That does include any locally set up dns records, since your are not setting those in a globally available way. You need to add a way for your drone container to use the gitea container, with traefik included, as your dns resolver.

Docker compose let's you do that using the following structure:

services:
 droneio:
  dns:
   - 8.8.8.8
   - gitea