502 Bad Gateway on Caddy Reverse Proxy to YOURLS Container (Docker)

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1. The problem I’m having:

I am trying to reverse proxy from a Caddy container (running on host network mode) to a YOURLS container on the same host machine. YOURLS is exposed to host port 8010. When accessing the domain https://link.atakanozban.com/admin/, however returns 502 Bad Gateway. I’ve already opened ports on my hosting provider.

2. Error messages and/or full log output:

{"level":"error","ts":1719958424,"logger":"http.log.error.log1","msg":"dial tcp 127.0.0.1:8010: connect: connection refused","request":{"remote_ip":"X.X.X.X","proto":"HTTP/2","method":"GET","host":"link.atakanozban.com","uri":"/admin/"},"duration":0.00124,"status":502,"err_id":"xyz123","err_trace":"...connection refused"}

3. Caddy version:

v2.11.4

4. How I installed and ran Caddy:

I installed and ran Caddy using Docker Compose.

System environment:

  • OS: Ubuntu 26.04 LTS

  • Docker Version: Docker Engine v27.0

  • Hosting: Hetzner Cloud VPS

b. Command:

docker compose up -d

c. Service/unit/compose file:

version: '3.3'

services:
  db:
    image: mariadb:10.11
    container_name: yourls-db
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: 'REDACTED_DB_ROOT_PASS'
      MYSQL_DATABASE: yourls
      MYSQL_USER: yourls
      MYSQL_PASSWORD: 'REDACTED_DB_PASS'
    volumes:
      - db_data:/var/lib/mysql

  yourls:
    image: yourls:latest
    container_name: yourls-app
    restart: always
    depends_on:
      - db
    ports:
      - "8010:80"
    environment:
      - YOURLS_SITE=https://link.atakanozban.com
      - YOURLS_USER=atakan
      - YOURLS_PASS=REDACTED_USER_PASS
      - YOURLS_DB_HOST=db
      - YOURLS_DB_USER=yourls
      - YOURLS_DB_PASS=REDACTED_DB_PASS

volumes:
  db_data:

d. My complete Caddy config:

link.atakanozban.com {    
    reverse_proxy 127.0.0.1:8010
}

5. Links to relevant resources:

I suspect it might be related to a docker network isolation or a similar issue discussed here: https://caddy.community/t/caddy-reverse-proxy-error-502-bad-gateway-on-docker/25353/2