Unix socket: add switch to disable adding the instance name to path

[eldad]

Feature Description

When creating a unix socket (-u), the name of the instance is concatenated to the path given by -u. This can cause an issue even if -u is very short: when using a long instance name, creating a UNIX socket can fail due to the length restriction.
(See also #970)

This can be avoided if cloud-sql-proxy would allow the user to disable adding the instance name as an extra directory, which is done here:

cloud-sql-proxy/internal/proxy/proxy.go

Line 892 in c683042

address = UnixAddress(dir, inst.Name)

I was able to workaround my local issues by building a custom version with address = dir at that line.
It would be great if there would be a switch to control this.

If this is acceptable to you, I'll be happy to contribute a PR to implement this.

Sample code

No response

Alternatives Considered

No response

Additional Details

Related issue: #970

With this simple change I can work with very long instance names:
https://github.com/eldad/cloud-sql-proxy/commit/950bb2a8e0502bd73dc0963fb1c6ed9e9eb78281
(obviously this behavior would need to be feature-flag controlled)

[hessjcg]

Hi, you are going to want to use the unix-socket-path parameter. This allows you to override the default socket path with your own, absolute path to the socket.

From the docs:

When necessary, you may specify the full path to a Unix socket. Set the
unix-socket-path query parameter to the absolute path of the Unix socket for
the database instance. The parent directory of the unix-socket-path must
exist when the Proxy starts or else socket creation will fail. For Postgres
instances, the Proxy will ensure that the last path element is
'.s.PGSQL.5432' appending it if necessary. For example,

      ./cloud-sql-proxy \
        'my-project:us-central1:my-db-server?unix-socket-path=/path/to/socket'

[eldad]

Thanks, I was not aware of this option!
It would be great if it would be at mentioned in the --help text.

[jackwotherspoon]

It would be great if it would be at mentioned in the --help text

@eldad It is mentioned in the --help text, albeit somewhat hidden in the text.

cloud-sql-proxy/cmd/root.go

Lines 160 to 169 in c683042

	When necessary, you may specify the full path to a Unix socket. Set the
	unix-socket-path query parameter to the absolute path of the Unix socket for
	the database instance. The parent directory of the unix-socket-path must
	exist when the Proxy starts or else socket creation will fail. For Postgres
	instances, the Proxy will ensure that the last path element is
	'.s.PGSQL.5432' appending it if necessary. For example,
	./cloud-sql-proxy \
	'my-project:us-central1:my-db-server?unix-socket-path=/path/to/socket'

[eldad]

Hidden in plain sight 😄 My bad, I didn't even notice the whole text before the command line switches. Thanks again!