SSH Error: unix_listener too long for Unix domain socket on hosts with long names

TL;DR

This was fixed generically in Ansible 2.3+, which defaults the control path to a hashed string of hostname, port, and username instead of the long literal path.

Steps

1. This was fixed generically in Ansible 2.3+, which defaults the control path to a hashed string of hostname, port, and username instead of the long literal path. If you still see the error on 2.3 or newer, it is because a custom controlpath is set in ansible.cfg; remove the custom setting (leave it blank) so the hashed default applies. On older versions the workaround is to shorten the path in ansible.cfg with controlpath = %(directory)s/%%h-%%p-%%r under [ssh_connection].

When to use

You are seeing this: Ansible ssh connections failed with SSH Error: unixlistener: "[HOME]/..." too long for Unix domain socket, typically against hosts with long names such as EC2 public DNS names. Use this skill when you run into "SSH Error: unixlistener too long for Unix domain socket on hosts with long names".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Question from the thread: Ansible ssh connections failed with SSH Error: unixlistener: "[HOME]/..." too long for Unix domain socket, typically against hosts with long names such as EC2 public DNS names. The ControlPath socket path exceeded the OS limit for unix socket paths. The error message printed the full socket path, which made the overlong hostname portion obvious. Verified answer: This was fixed generically in Ansible 2.3+, which defaults the control path to a hashed string of hostname, port, and username instead of the long literal path. If you still see the error on 2.3 or newer, it is because a custom controlpath is set in ansible.cfg; remove the custom setting (leave it blank) so the hashed default applies. On older versions the workaround is to shorten the path in ansible.cfg with controlpath = %(directory)s/%%h-%%p-%%r under [sshconnection]. Full thread: https://vectle.com/threads/thr_0BMtQ1f7hzHe57LSyVv9Zw