[RFC]/[WIP] Add Python 2.7 deprecation warning

[punkrokk]

At today's TSC meeting, the subject of python 2.7 deprecation was discussed. Although the exact timeline for removing Python 2.7 support from is not yet known, the TSC agreed that it made sense to add a deprecation warning to installs that use Python 2.7.

Things that may need to be decided before this issue can be worked:

• Do this by OS/Package
• st2client
• st2 pack install
• logs
• st2web?
• When to show the deprecation warning
• other things I'm not thinking of

[nmaludy]

Couple thoughts...

• Definitely python 3 only on new OSes
• I know there is a python3.6 install path in RHEL 7, so support for python3 only should be OK there as long as the user has the packages installed.
• Not sure about python3 on Ubuntu 16.04?
• The phase out time of rhel7/ubuntu16 might be longer than we want to keep python2 around? Especially considering rhel8 and ubuntu18 andare relatively new.

👍 for depreciation warnings for python 2 users. Probably want to show that at various parts of the cli and maybe install process... potentially web ui?

[arm4b]

There are 2 types of deprecation warnings that might be useful:

• When using OS w python2 (currently EL7 and U16)
• When using python2 packs
  • Output a warning during the st2 pack install
  • Include warnings in st2 logs

@blag Want to start the dedicated Python2 deprecation discussion and also the new project in Github so we could get everything organized?

[cognifloyd]

Deprecation notices need to be in rpm, deb, and (at least for st2client) wheel.
Other possible places for deprecation warnings: the installers could print warnings, on startup (or even periodically?), all of the st2* packages could print and log a deprecation warning if running under py2.7. st2client could print a warning every time you auth or login.

Can we build rpm/deb variants so that people can select to install py3 before the official deprecation period is up on EL7/U16? Then, at the end of the period, the next release obsoletes both packages?

[arm4b]

As we're getting closer to v3.3.0 release, any takers to start adding the py2 deprecation warnings in various system parts?
As earlier we would start injecting it and communicating python 2 deprecation, - faster we can get rid of old python 2.

@StackStorm/maintainers and @StackStorm/contributors.

[amanda11]

I'll aim to start looking at adding a warning if you install a python 2 only pack next week - plan to add warning to REST API call, and CLI (I'll test what happens on the UI as well - but may or may not manage to fix UI depending on how much UI knowledge I need - but will make sure I don't break it!)

[arm4b]

@amanda11 did a great job adding python 2 deprecation warning to:

1. st2 pack install
2. st2ctl
3. st2 services logs on startup
4. @StackStorm/maintainers @StackStorm/contributors Do we want a py2 deprecation warning when installing U16 .deb and EL7 .rpm packages as well or it was enough of warnings?

[nmaludy]

I don' think we need deprecation warnings on the RPMs or DEBs IMO

[arm4b]

Thanks, everyone for brainstorming and @amanda11 for implementation. Closing this as Done 👍!

We'll still need someone from @StackStorm/maintainers to write a blog post about Python 2 future plans to keep our community up to date with the deprecation effort and give everyone enough time for migration.