Add PERSISTED_FEATURE_FLAGS env

[mariusandra]

Changes

• This adds an env, PERSIST_FEATURE_FLAGS that overrides feature flags in the frontend, at least the ones in the featureFlagLogic.
• We can hardcode a value into this env inside settings.py to burn some flags into a release.
• Running with the env PERSIST_FEATURE_FLAGS=4267-taxonomic-property-filter,4535-funnel-bar-viz and not having those flags in the system, I had the new filter and the new funnels working.
• All other flags (those not in the env/setting, but still coming in with /decide) are passed through as they are.

Checklist

• All querysets/queries filter by Organization, by Team, and by User
• Django backend tests
• Jest frontend tests
• Cypress end-to-end tests
• Migrations are safe to run at scale (e.g. PostHog Cloud) – present proof if not obvious
• New/changed UI is decent on smartphones (viewport width around 360px)

[macobo]

Q: What is this solving?

[mariusandra]

We want to enable code that's behind flags 4267-taxonomic-property-filter and 4535-funnel-bar-viz in the next release. We can either make a PR to remove the flags altogether, or hardcode them in, so we could eventually remove them on app and not worry about breaking old deployments running 1.27.

So "what is this solving"? Literally the issue you opened with the fix you suggested 😁

The idea is that in a release branch before pushing it out, we edit the hardcoded list in settings.py.

[mariusandra]

Two questions I'd have here:

1. Do we want to force-enable only certain flags like we do now in this PR... and leave everything else dynamic (via /decide).... or do we want to completely ignore whatever /decide returns.
2. Naming things. PERSIST?

[timgl]

I think this is a decent solution. I wonder if it would be cleaner to before a release just remove all feature flags instead but I don't feel strongly about it.

Do you want to add 4267-taxonomic-property-filter,4535-funnel-bar-viz to this PR?

[mariusandra]

Actually, yes, let's just really release it. Updates:

• I added 4267-taxonomic-property-filter, 4535-funnel-bar-viz and save-cohort-on-modal (new one that I found, wasn't in a constant, fixed in Fix persons modal load more people #5271) to settings.
• If this is merged, then these will now be released on cloud as well to everyone.
• I also found a bunch of non-constant feature flags and moved them to constants.tsx. Except for save-cohort-on-modal which will be added in that PR.

[paolodamico]

Some comments/suggestions, but lgtm!

[mariusandra]

Of course now that the flags are force-enabled, all cypress tests fail because we never developed test with the flags on. Probably the taxonomic filter is causing issues here 😅.

[mariusandra]

On second thought, I will remove the released features themselves from this PR. Releasing them will require bigger changes to the tests and I fear this PR will get way too messy then.

Any objections to merging it in as is? I have 1 approval from @paolodamico , so merging when tests pass. I'll create separate a new PR for the actual flags.

Edit: here it is #5282