[cli] Preparing to deprecate wrapping of external commands

[john-bodley]

This PR indicates to users that the Superset CLI commands which wrap external commands such as gunicorn, celery, and flower are deprecated prior to removing the functionality at a later stage.

The reason for the change is:

1. All these commands can be run via the delegated application.
2. The current approach only exposes a limited number of command line arguments.
3. It provides unnecessary dependencies which aren't core to the application.

to: @fabianmenges @mistercrunch

[xrmx]

This looks like painful for newcomers coming from outside the python world who have no clue on how to deploy a wsgi app though. The fact that superset looked like an http service while it's just a flask application it's handy to me, also quite "cloud native" :) Would it be possible to keep the dependencies and just remove the wrappers? Anyway if we remove the wrapper we have to provide the equivalent of superset runserver in the docs if we don't want to get swamped with github issues please.

[mistercrunch]

Having some docker / docker-compose predefined setup(s) could help compensate in a better-than-its-now kind of way.

Personally cannot commit time to this but I think that'd be the modern alternative for good and easy setup.

[codecov-io]

Codecov Report

Merging #4451 into master will decrease coverage by 0.03%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #4451      +/-   ##
==========================================
- Coverage   71.88%   71.85%   -0.04%     
==========================================
  Files         204      204              
  Lines       15329    15317      -12     
  Branches     1177     1177              
==========================================
- Hits        11020    11006      -14     
- Misses       4306     4308       +2     
  Partials        3        3

Impacted Files	Coverage Δ
superset/cli.py	46.83% <0%> (-0.91%)	⬇️
superset/config.py	92.24% <100%> (ø)	⬆️
superset/utils.py	88.05% <0%> (-0.17%)	⬇️
superset/connectors/sqla/views.py	71.56% <0%> (ø)	⬆️
superset/connectors/druid/views.py	68.02% <0%> (ø)	⬆️

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[fabianmenges]

For celery the gevent flag is -P gevent

[john-bodley]

Thanks. I added --pool=gevent. I've used the long names as they're more descriptive.

[fabianmenges]

We are running gunicorn with gevent which make superset more efficient handling requests -k gevent

[john-bodley]

@fabianmenges the -k gevent argument is specified.

[john-bodley]

@fabianmenges are you ok with the changes I made per your request?

[jeffreythewang]

I do somewhat agree with @xrmx that it may be painful for newcomers, at least for the gunicorn wrapper. I still (and will probably still) use the superset cli wrapper as a shortcut for quickly spinning up an app locally.

[jeffreythewang]

nit: typo

[jeffreythewang]

minor: would these configs (and the rest of the config vars that are only used in cli.py also be tagged as # deprecated?

[john-bodley]

@jeffreythewang I added SUPERSET_WEBSERVER_TIMEOUT. Am I missing other config variables from the commands which are slated to be deprecated?

[jeffreythewang]

Sorry for the late response. I primarily meant it as adding a # deprecated and [DEPRECATED] comment, both in cli.py and the sample config.py, to the environment variables that are deprecated. I might be wrong, but I only see SUPERSET_WEBSERVER_PORT, SUPERSET_WEBSERVER_ADDRESS, and FLASK_USE_RELOAD used in cli.py.