Use only via Unix sockets(without TCP)

[ch1c0t]

Hi, thanks for LavinMQ and for making it in public.

I am trying to set it up so that it be accessible only via Unix sockets. Each user on my Debian system would have a dedicated LavinMQ instance for user-specific needs.

Here is my setup so far, made with mitamae.

It seems to work, but it also starts to listen on TCP ports:

Jan 30 22:17:34 desk systemd[1889]: Started lavinmq.service - LavinMQ Message Broker.                                                                          
Jan 30 22:17:34 desk lavinmq[13302]:  lmq[level: "Info", target: "stdout"] Logger settings                                                                     
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher LavinMQ 2.6.5                                                                                               
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher Crystal 1.18.2 (2025-10-21)                                                                                 
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher LLVM: 19.1.7                                                                                                
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher Default target: x86_64-pc-linux-gnu                                                                         
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher Build flags: --release --debug                                                                              
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher Multithreading: 4 threads                                                                                   
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher PID: 13302                                                                                                  
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher Config file: /home/om/.config/lavinmq/lavinmq.ini                                                           
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher Data directory: /home/om/.local/share/lavinmq/data                                                          
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher Max mmap count: 1048576                                                                                     
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.launcher FD limit: 524288                                                                                            Jan 30 22:17:34 desk lavinmq[13302]:  systemd.memory_pressure Monitoring memory pressure on regular file: /sys/fs/cgroup/user.slice/user-1001.slice/user@1001.s
ervice/app.slice/lavinmq.service/memory.pressure                                                                                                               
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.vhost[vhost: "/"] Loading default definitions                                                                        
Jan 30 22:17:34 desk lavinmq[13302]:  lmq.vhost[vhost: "/"] Compacting definitions                                                                 
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.vhost_store Created vhost /                                                                                          
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.http.server Bound to 127.0.0.1:15672                                                                                 
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.http.server Bound to /home/om/.local/share/lavinmq/mgmt.sock                                                         
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.http.server Bound to /tmp/lavinmqctl.sock                                                                            
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.metrics.server Bound to 127.0.0.1:15692                                                                              
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.server Listening for AMQP on 127.0.0.1:5672                                                                          
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.server Listening for AMQP on /home/om/.local/share/lavinmq/amqp.sock                                                 
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.server Listening for MQTT on 127.0.0.1:1883                                                              
Jan 30 22:17:35 desk lavinmq[13302]:  lmq.launcher Finished startup in 0.236931284s                                                                

Could you advise on how to disable listening on TCP ports and make it work only via Unix sockets?

[carlhoerberg]

Set port to -1

[ch1c0t]

Thanks, it worked.

[ch1c0t]

This answers the first part of my question(namely, listening on TCP ports).

However, I haven't succeeded yet in making it work via Unix socket.

This Crystal client reports, after a few seconds of wait, that the connection was closed by server:

1% shards run
Dependencies are satisfied
Building: amqp_via_unix_sockets
Executing: amqp_via_unix_sockets 
Path["/home/om/.local/share/lavinmq/amqp.sock"]
Unhandled exception: Connection closed by server host=/home/om/.local/share/lavinmq/amqp.sock user=guest vhost=/ (AMQP::Client::Connection::ClosedException)
  from lib/amqp-client/src/amqp-client.cr:146:10 in 'connect'
  from lib/amqp-client/src/amqp-client.cr:43:12 in '__crystal_main'
  from /home/om/.local/share/mise/installs/crystal/1.18.2/share/crystal/src/crystal/main.cr:129:5 in 'main_user_code'
  from /home/om/.local/share/mise/installs/crystal/1.18.2/share/crystal/src/crystal/main.cr:115:7 in 'main'
  from /home/om/.local/share/mise/installs/crystal/1.18.2/share/crystal/src/crystal/system/unix/main.cr:9:3 in 'main'
  from /lib/x86_64-linux-gnu/libc.so.6 in '??'
  from /lib/x86_64-linux-gnu/libc.so.6 in '__libc_start_main'
  from /home/om/sources/crystal/amqp_via_unix_sockets/bin/amqp_via_unix_sockets in '_start'
  from ???

[ch1c0t]

I see in the server logs:

Feb 01 21:46:11 desk lavinmq[1941]:  lmq.server Error accepting connection from /home/om/.local/share/lavinmq/amqp.sock
Feb 01 21:46:11 desk lavinmq[1941]:  Error accepting connection from /home/om/.local/share/lavinmq/amqp.sock (IO::TimeoutError)
Feb 01 21:46:11 desk lavinmq[1941]:    from /usr/share/crystal/src/crystal/system/thread.cr:82:3 in 'unbuffered_read'
Feb 01 21:46:11 desk lavinmq[1941]:    from /usr/share/crystal/src/io/buffered.cr:273:5 in 'peek'
Feb 01 21:46:11 desk lavinmq[1941]:    from /usr/share/crystal/src/io.cr:717:18 in '->'
Feb 01 21:46:11 desk lavinmq[1941]:    from /usr/share/crystal/src/fiber.cr:170:11 in 'run'
Feb 01 21:46:11 desk lavinmq[1941]:    from ???

It's not yet clear to me why.

[carlhoerberg]

Set unix_proxy_protocol to 0, it unfortunately defaults to 1

lavinmq/src/lavinmq/config.cr

Line 27 in 8a9151a

property unix_proxy_protocol = 1_u8 # PROXY protocol version on unix domain socket connections