unix-socket maximal path length exceeded when cloudsql-proxy tries to open a unix socket in the directory specified by -dir parameter

[Manan007224]

Description

When we start cloudsql-proxy using unix sockets using this command

./cloud_sql_proxy -dir=/cloudsql -instances=INSTANCE_CONNECTION_NAME
-credential_file=PATH_TO_KEY_FILE &

cloudsql-proxy opens a unix socket in the path /cloudsql/INSTANCE_CONNECTION_NAME. However unix-socket paths have a path lenght limit dependent on the platform it runs. If the unix socket path length exceeds the limit cloudsql-proxy throws the following error :-
bind: invalid argument.

While this could be solved by overriding the -dir parameter and provinding an absolute path in the -instance parameter, the issue of unix socket path limit should be documented somewhere, so that the users are aware of this.

[enocom]

Thanks for the bug report @Manan007224. It seems like the proxy could return a better error, in addition to whatever documentation changes we make.

[enocom]

Here are some details about the unix socket path length. Adding this here for reference:

https://unix.stackexchange.com/a/367012/26069