[GitHub] [apisix-docker] ChristophBaierATB commented on issue #470: nginx: [emerg] bind() to unix:/usr/local/apisix/conf/config_listen.sock failed (98: Address already in use)

["ChristophBaierATB (via GitHub)" <gi...@apache.org>]

ChristophBaierATB commented on issue #470:
URL: https://github.com/apache/apisix-docker/issues/470#issuecomment-1633956607

   ## Reproduction of the Bug
   
   ### Minimal Setup
   
   Create these two files in the same directory:
   
   1. docker-compose.yml
   
      ```yaml
      version: "3"
      services:
        etcd:
          image: bitnami/etcd:3.4.15
          container_name: etcd
          environment:
            ETCD_ENABLE_V2: "true"
            ALLOW_NONE_AUTHENTICATION: "yes"
            ETCD_ADVERTISE_CLIENT_URLS: "http://etcd:2379"
            ETCD_LISTEN_CLIENT_URLS: "http://0.0.0.0:2379"
      
        apisix:
          image: apache/apisix:3.3.0-debian
          container_name: apisix
          depends_on:
            - etcd
          volumes:
            - ./config.yaml:/usr/local/apisix/conf/config.yaml:ro
      ```
   
   2. config.yaml
   
      ```yaml
      deployment:
        etcd:
          host:
            - "http://etcd:2379"
          prefix: "/apisix"
          timeout: 30
      ```
   
   Start the setup:
   
   ```bash
   docker-compose up -d
   ```
   
   Both services should start successfully.
   
   
   
   ### Trigger the Bug
   
   ```bash
   docker kill apisix # simulate host crash
   docker-compose up -d # start the container again 
   docker logs apisix
   ```
   
   Output:
   
   ```
   ...
   2023/07/13 09:41:38 [emerg] 1#1: bind() to unix:/usr/local/apisix/conf/config_listen.sock failed (98: Address already in use)
   nginx: [emerg] bind() to unix:/usr/local/apisix/conf/config_listen.sock failed (98: Address already in use)
   ...
   ```
   
   
   
   ### Possible Explanation
   
   * When APISIX container starts, it creates a lock file for `config_listen.sock`, indicating that it is already in use. This prevents multiple APISIX processes from starting and accessing this socket at the same time. When the container is gracefully stopped (e.g. via `docker stop apisix`), this lock file is deleted. When the APISIX container is restarted (e.g. via `docker start apisix`), it can create a new lock file, so no problem.
   * When APISIX container is shut down by force, e.g. by a host crash (simulated by `docker kill apisix`), the container will not shut down gracefully and the lock file will not be deleted. It persists within the docker container. When the host is rebooted and the APISIX container is started again, APISIX will try to create a lock file, but since such a file already exists, APISIX will think that the socket is already in use, leading to the above error message.
   
   
   
   ### Workaround Solution
   
   It is possible to simply delete the container and start a new one that does not contain the lock file.
   
   ```bash
   docker rm -f apisix
   docker-compose up -d
   ```
   
   However, this will not solve the problem, as it will recur every time the host crashes and restarts.


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