Can't connect to host-listening UNIX-SOCKET from container/VM

Docker Desktop
1

Expected behavior

On OSX Side:
socat -d -d - UNIX-LISTEN:/tmp/.X11-unix/X1,fork
2016/06/15 00:49:02 socat[2062] N reading from and writing to stdio
2016/06/15 00:49:02 socat[2062] N listening on LEN=19 AF=1 “/tmp/.X11-unix/X1”
2016/06/15 00:49:32 socat[2062] N accepting connection from LEN=16 AF=1 “” on LEN=19 AF=1 “/tmp/.X11-unix/X1”
2016/06/15 00:49:32 socat[2062] N forked off child process 2067
2016/06/15 00:49:32 socat[2062] N listening on LEN=19 AF=1 “/tmp/.X11-unix/X1”
2016/06/15 00:49:32 socat[2067] N starting data transfer loop with FDs [0,1] and [6,6]
2016/06/15 00:49:58 socat[2067] N socket 2 (fd 6) is at EOF
2016/06/15 00:49:59 socat[2067] N exiting with status 0
2016/06/15 00:49:59 socat[2062] N childdied(): handling signal 20

On VM/Container Side
socat -d -d UNIX-CONNECT:/tmp/.X11-unix/X1 -
2016/06/15 00:58:22 socat[2127] N opening connection to LEN=19 AF=1 “/tmp/.X11-unix/X1”
2016/06/15 00:58:22 socat[2127] N successfully connected from local address LEN=16 AF=1 “”
2016/06/15 00:58:22 socat[2127] N reading from and writing to stdio
2016/06/15 00:58:22 socat[2127] N starting data transfer loop with FDs [5,5] and [0,1]

Actual behavior

On VM
moby:/tmp/.X11-unix# socat -d -d UNIX-CONNECT:./X1 -
2016/06/15 03:59:28 socat[2784] N opening connection to AF=1 “./X1”
2016/06/15 03:59:28 socat[2784] E connect(5, AF=1 “./X1”, 6): Connection refused
2016/06/15 03:59:28 socat[2784] N exit(1)

On Container
[root@b6bf31098e33 tmp]# socat -d -d UNIX-CONNECT:/tmp/.X11-unix/X1 -
2016/06/15 04:01:00 socat[18] N opening connection to AF=1 “/tmp/.X11-unix/X1”
2016/06/15 04:01:00 socat[18] E connect(3, AF=1 “/tmp/.X11-unix/X1”, 19): Connection refused
2016/06/15 04:01:00 socat[18] N exit(1)

Information

  • the output of:

Docker for Mac: version: mac-v1.11.2-beta15
OS X: version 10.11.5 (build: 15F34)
logs: /tmp/20160615-010451.tar.gz
failure: No error was detected
[OK] docker-cli
[OK] app
[OK] menubar
[OK] virtualization
[OK] system
[OK] osxfs
[OK] db
[OK] slirp
[OK] moby-console
[OK] logs
[OK] vmnetd
[OK] env
[OK] moby
[OK] driver.amd64-linux

Darwin 15.5.0 Darwin Kernel Version 15.5.0: Tue Apr 19 18:36:36 PDT 2016; root:xnu-3248.50.21~8/RELEASE_X86_64 x86_64

Steps to reproduce the behavior

  1. install socat on OSX, VM and/or Container
  2. run socat -d -d - UNIX-LISTEN:/tmp/.X11-unix/X1,fork on OSX
  3. run socat -d -d UNIX-CONNECT:/tmp/.X11-unix/X1 - on VM and/or Container.

socat run on OSX as normal user.
socat run on VM/Container as root.
docker run commando, run both as normal user, or sudo as root with same behavior.

1 Like
2

I also this problem when mounting volumes with sockets.

Wondering why it works with the docker.sock and not with our own sockets.

3

Please see the File Types section in the docs at https://docs.docker.com/docker-for-mac/osxfs/#file-types. The docker.sock has a special case with an OS X-side server listening to it. We have plans for generic trans-hypervisor Unix domain socket support (it’s on the roadmap) but we haven’t yet built all necessary components or integrated them into development builds.

The near-term workaround is to use TCP sockets (listening on local interfaces only) with something like socat to pipe through socket files.

Hope this helps,

David

1 Like
4

Thanks for the help @dsheets. I will do it using TCP sockets.