feat(feature-flags): support quota limiting for feature flags #1758

dmarticus · 2025-02-22T00:59:10Z

with PostHog/posthog#28564, we now start to respond different with the /decide and /local_evaluation APIs if users have gone over their quota limit. Now we need to change the SDKs to handle these new responses.

vercel · 2025-02-22T00:59:15Z

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greptile-apps

PR Summary

This PR implements quota limiting support for feature flags in the PostHog JavaScript SDK, handling cases where users exceed their feature flag usage limits.

Added QuotaLimitedResource enum in src/posthog-featureflags.ts to identify quota-limited resources
Added quota limit check in /decide endpoint response handling to prevent flag processing when limits are exceeded
Added warning message directing users to documentation when feature flag quota is exceeded
Added comprehensive test suite in src/__tests__/posthog-core.loaded.test.ts covering quota limiting scenarios
Implemented graceful degradation by preserving existing flag states when quota is exceeded

_{2 file(s) reviewed, 4 comment(s)}
_{Edit PR Review Bot Settings | Greptile}

src/__tests__/posthog-core.loaded.test.ts

greptile-apps · 2025-02-22T00:59:39Z

src/__tests__/posthog-core.loaded.test.ts

+            mockLogger = jest.spyOn(console, 'warn').mockImplementation()
+            instance = await createPosthog()


style: Console warning spy is created but no tests verify warning messages for quota limiting

greptile-apps · 2025-02-22T00:59:46Z

src/posthog-featureflags.ts

+enum QuotaLimitedResource {
+    FeatureFlags = 'feature_flags',
+    Recordings = 'recordings',
+}


style: Consider making this enum exported since it may be useful for other parts of the codebase that need to handle quota limiting

greptile-apps · 2025-02-22T00:59:47Z

src/posthog-featureflags.ts

@@ -302,6 +307,15 @@ export class PostHogFeatureFlags {
                }

                this._flagsLoadedFromRemote = !errorsLoading


logic: Setting _flagsLoadedFromRemote before checking quota could be misleading since flags aren't actually loaded when quota is exceeded

Suggested change

this._flagsLoadedFromRemote = !errorsLoading

if (response.json && response.json.quotaLimited?.includes(QuotaLimitedResource.FeatureFlags)) {

// log a warning and then early return

logger.warn(

'You have hit your feature flags quota limit, and will not be able to load feature flags until the quota is reset. Please visit https://posthog.com/docs/billing/limits-alerts to learn more.'

)

return

}

this._flagsLoadedFromRemote = !errorsLoading

yeah, but the variable name _flagsLoadedFromRemote is a bit misleading too – it implies that we're trying to use the flags from the /decide service, not that we actually end up using them.

github-actions · 2025-02-22T01:03:30Z

Size Change: +3.72 kB (+0.11%)

Total Size: 3.32 MB

Filename	Size	Change
`dist/array.full.es5.js`	270 kB	+376 B (+0.14%)
`dist/array.full.js`	373 kB	+372 B (+0.1%)
`dist/array.full.no-external.js`	372 kB	+372 B (+0.1%)
`dist/array.js`	183 kB	+372 B (+0.2%)
`dist/array.no-external.js`	182 kB	+372 B (+0.2%)
`dist/main.js`	184 kB	+372 B (+0.2%)
`dist/module.full.js`	373 kB	+372 B (+0.1%)
`dist/module.full.no-external.js`	372 kB	+372 B (+0.1%)
`dist/module.js`	183 kB	+372 B (+0.2%)
`dist/module.no-external.js`	182 kB	+372 B (+0.2%)

ℹ️ View Unchanged

Filename	Size
`dist/all-external-dependencies.js`	218 kB
`dist/customizations.full.js`	14 kB
`dist/dead-clicks-autocapture.js`	14.5 kB
`dist/exception-autocapture.js`	9.51 kB
`dist/external-scripts-loader.js`	2.64 kB
`dist/recorder-v2.js`	115 kB
`dist/recorder.js`	115 kB
`dist/surveys-preview.js`	70.1 kB
`dist/surveys.js`	74.8 kB
`dist/tracing-headers.js`	1.76 kB
`dist/web-vitals.js`	10.4 kB

_{compressed-size-action}

dmarticus · 2025-02-25T19:17:52Z

src/__tests__/posthog-core.loaded.test.ts

@@ -15,7 +15,7 @@ describe('loaded() with flags', () => {
            ...config,
            loaded: (ph) => {
                ph.capture = jest.fn()
-                ph._send_request = jest.fn(({ callback }) => callback?.({ status: 200, json: {} }))
+                ph._send_request = jest.fn(({ callback }) => callback?.({ statusCode: 200, json: {} }))


had to fix a squiggly red line

Squiggly red lines are the worst!

dmarticus · 2025-02-25T19:18:33Z

src/posthog-featureflags.ts

+                if (response.json && response.json.quotaLimited?.includes(QuotaLimitedResource.FeatureFlags)) {
+                    // log a warning and then early return
+                    logger.warn(
+                        'You have hit your feature flags quota limit, and will not be able to load feature flags until the quota is reset.  Please visit https://posthog.com/docs/billing/limits-alerts to learn more.'


This warning feels a bit too long – what do folks think?

It seems to be a lot longer than the other libraries. EIther we should go more detailed in all of them (with the URL), or keep them all short and make sure searching PostHog will find that page easily.

Yeah, I have a docs PR for this here: PostHog/posthog.com#10653, but that's mostly for the API and it doesn't include information on resolution. It feels appropriate to put that in the logs for the SDKs. I think I'll do this everywhere, actually – if it were me using the SDK I'd be please to see a link to how to resolve a warning log in the log itself.

dmarticus · 2025-02-25T19:23:27Z

src/posthog-featureflags.ts

@@ -302,6 +307,15 @@ export class PostHogFeatureFlags {
                }

                this._flagsLoadedFromRemote = !errorsLoading


yeah, but the variable name _flagsLoadedFromRemote is a bit misleading too – it implies that we're trying to use the flags from the /decide service, not that we actually end up using them.

haacked

Looks good to me.

haacked · 2025-02-25T19:42:24Z

src/__tests__/posthog-core.loaded.test.ts

@@ -15,7 +15,7 @@ describe('loaded() with flags', () => {
            ...config,
            loaded: (ph) => {
                ph.capture = jest.fn()
-                ph._send_request = jest.fn(({ callback }) => callback?.({ status: 200, json: {} }))
+                ph._send_request = jest.fn(({ callback }) => callback?.({ statusCode: 200, json: {} }))


Squiggly red lines are the worst!

haacked · 2025-02-25T19:44:13Z

src/posthog-featureflags.ts

+                if (response.json && response.json.quotaLimited?.includes(QuotaLimitedResource.FeatureFlags)) {
+                    // log a warning and then early return
+                    logger.warn(
+                        'You have hit your feature flags quota limit, and will not be able to load feature flags until the quota is reset.  Please visit https://posthog.com/docs/billing/limits-alerts to learn more.'


It seems to be a lot longer than the other libraries. EIther we should go more detailed in all of them (with the URL), or keep them all short and make sure searching PostHog will find that page easily.

dmarticus added 2 commits February 21, 2025 16:56

did the damn thing

d550d9d

merge conflicts on god

c542e79

greptile-apps bot reviewed Feb 22, 2025

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vercel bot deployed to Preview February 22, 2025 01:02 View deployment

dmarticus requested a review from a team February 25, 2025 18:46

clean up tests

2c85b71

vercel bot deployed to Preview February 25, 2025 19:21 View deployment

dmarticus commented Feb 25, 2025

View reviewed changes

haacked approved these changes Feb 25, 2025

View reviewed changes

This was referenced Feb 25, 2025

chore(flags): improved some logs for quota limiting PostHog/posthog-python#197

Merged

chore(flags): more quota limit logs PostHog/posthog-android#230

Merged

chore(flags): update quota-limited logs PostHog/posthog-dotnet#58

Merged

dmarticus added the bump minor Bump minor version when this PR gets merged label Feb 26, 2025

dmarticus merged commit ace91db into main Feb 27, 2025
28 checks passed

dmarticus deleted the feat/quota-limited-flags branch February 27, 2025 00:26

		mockLogger = jest.spyOn(console, 'warn').mockImplementation()
		instance = await createPosthog()

		@@ -302,6 +307,15 @@ export class PostHogFeatureFlags {
		}

		this._flagsLoadedFromRemote = !errorsLoading

feat(feature-flags): support quota limiting for feature flags #1758

feat(feature-flags): support quota limiting for feature flags #1758

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vercel bot commented Feb 22, 2025 •

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