cli: cockroach init lack of argument validation leads to confusing error message

[rmloveland]

FEATURE REQUEST

1. Does an issue already exist addressing this request? If yes, please add a 👍 reaction to the existing issue. If not, move on to step 2.

I did not find anything via 'cli is:open'

2. Please describe the feature you are requesting, as well as your proposed use case for this feature.

1. cockroach start --join accepts hosts in the format host:port
2. cockroach init requires separate --host and --port arguments, which would be slightly odd but fine, except that
3. If you assume (based on your experience with cockroach start) that the incorrect cockroach init --host=localhost:12345 will work, it doesn't give you an invalid argument error and exit, it (apparently?) passes the bad arg through and you get a networking error (pasted below). I spent waaaaay too much time scratching my head before realizing that this was due to a bad argument and not something "network-y" on my machine. This is especially confusing because (a) I'm not a networking expert, and (b) the error message is talking about RPCs and credentials and such.

The feature request is that cockroach init validate its arguments and print an error message and exit instead of the current behavior.

Error message for incorrect --host arg to cockroach init:

/Users/rloveland/bin/cockroach init --insecure --host=localhost:26500

E180410 12:45:12.324448 1 cli/error.go:109  unable to connect or connection lost.

Please check the address and credentials such as certificates (if attempting to
communicate with a secure cluster).

initial connection heartbeat failed: rpc error: code = Unavailable desc = all SubConns are in TransientFailure
Error: unable to connect or connection lost.

Please check the address and credentials such as certificates (if attempting to
communicate with a secure cluster).

initial connection heartbeat failed: rpc error: code = Unavailable desc = all SubConns are in TransientFailure
Failed running "init"

[knz]

cc @bdarnell for triage

[bdarnell]

init is like all the other client commands in this respect, so this is a duplicate of #23277.