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socketsdockerdocker-composehaproxy

Volume mount haproxy socket from HAProxy docker container

I want to give a peer container access to /var/run/haproxy.sock. Unfortunately, it throws an error when I try to do this through bind mounting with a named volume. Is is possible to share the haproxy.sock with other containers? I assume it is, so I wonder which piece I am missing here. Probably rights - but how to set them correctly?

worker1    | <7>haproxy-systemd-wrapper: executing /usr/local/sbin/haproxy -p /run/haproxy.pid -f /usr/local/etc/haproxy/haproxy.cfg -Ds
worker1    | [ALERT] 182/075644 (6) : Starting frontend GLOBAL: error when trying to preserve previous UNIX socket [/var/run/haproxy.sock]
worker1    | <5>haproxy-systemd-wrapper: exit, haproxy RC=1

I have the following config in haproxy.cfg:

global
    maxconn 8204
    tune.ssl.default-dh-param 2048
    stats socket /var/run/haproxy.sock mode 660 level admin
    stats timeout 30s

I use docker-compose to start my containers in swarm mode:

version: '3.2'

services:
  haproxy:
    image: haproxy:1.7.7
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - "/home/ubuntu/haproxy/haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg:ro"
      - "socket:/var/run/haproxy.sock:rw"
    ulimits:
      nofile:
        soft: 16479
        hard: 16479
    deploy:
      placement:
        constraints:
          - node.hostname==worker1

volumes:
  socket: {}
Solution

  • Named volumes can only be directories, not single files. As a result, this line;

    "socket:/var/run/haproxy.sock:rw"

    Will attempt to mount a directory (the "socket" volume) at location /var/run/haproxy.sock inside the container.

    If the location of "haproxy.sock" is configurable, you may try something like;

    "socket:/my-haproxy-socket-directory"

    (the socket itself would be located at /my-haproxy-socket-directory/haproxy.sock inside the container)