`tensorboard` should support `--version`

[wchargin]

When dealing with path issues, such as when users (mistakenly) have
multiple versions of TensorBoard installed or are trying to coordinate
modules from multiple sources (e.g., a virtualenv plus system site
packages), having tensorboard --version would be helpful. It’s also
useful as a minimal “is TensorBoard installed?” command that’s less
verbose than tensorboard --helpshort (131 lines) and more portable
than which tensorboard (it’s where tensorboard on Windows).

Plus, come on: everything supports --version. :-)

[thealphacod3r]

@wchargin can you guide me on this I would love to work on this!!

[wchargin]

Hi @amanp592! Yes, this is probably a good starter issue.

You’ll want to define a new --version flag. There’s not a clearly
correct place for this flag to live, but it seems reasonable enough to
add it to core_plugin.py’s define_flags method. Then, in fix_flags
in the same file, you can print out the version and exit with success if
the --version flag was passed.

Let us know if you have questions.

[nfelt]

I think it might be a bit better to implement the version printing in tensorboard.program.Tensorboard.main, which is the way it works for --inspect:

tensorboard/tensorboard/program.py

Lines 219 to 223 in 58df24b

	if self.flags.inspect:
	logger.info('Not bringing up TensorBoard, but inspecting event files.')
	event_file = os.path.expanduser(self.flags.event_file)
	efi.inspect(self.flags.logdir, event_file, self.flags.tag)
	return 0

That seems slightly cleaner than just calling sys.exit() in the flag processing code itself since it keeps the functional behavior of main() all in one place and the flag processing just focused on flag processing.

[wchargin]

I think it might be a bit better to implement the version printing in
tensorboard.program.Tensorboard.main, which is the way it works for
--inspect:

That’s also fine with me, given that inspect works that way already.

(For what it’s worth, IMHO this isn’t entirely satisfactory, either,
because really main should not depend on any plugin… and really it’s
questionable whether core_plugin should be a plugin at all.)

[nfelt]

Yes, I think the problem there is that we have been putting flags that really relate mostly to program itself into CorePlugin for lack of a better place.

[shashvatshahi1998]

@wchargin, @nfelt can you please tell me what else i have to add in this PR.

[nfelt]

Fixed by #2097.