feat: adds RequireFlagsEnabled decorator #1159

kaushalkapasi · 2025-03-14T20:08:14Z

This PR

Feature: Adds a RequireFlagsEnabled decorator to allow a simple, reusable way to block access to a specific controller or endpoint based on the value of a list of one, or many, boolean flags

Notes

Discussions on the approach & implementation are welcome!

Follow-up Tasks

Update OpenFeature NestJS docs to include new RequireFlagsEnabled decorator & usage examples

How to test

npx jest --selectProject=nest

toddbaert · 2025-03-20T19:43:05Z

I think this is a good idea, and it "feels right" to me ergonomically.

Make sure you add something to the test-app to test and document this.

lukas-reining

I really like the addition!
Added some optional additions to it. Feel free to add them, otherwise we can add them in another PR :)
Thank you!

packages/nest/src/require-flags-enabled.decorator.ts

lukas-reining · 2025-03-25T21:10:13Z

packages/nest/src/require-flags-enabled.decorator.ts

+/**
+ * Options for injecting a feature flag into a route handler.
+ */
+interface RequireFlagsEnabledProps {


Also we could have a context factory here too. Basically what we globally have for the OpenFeatureModule:

js-sdk/packages/nest/src/open-feature.module.ts

Line 138 in cf89e7d

contextFactory?: ContextFactory;

But this would be optional to me. We do not have it for the other decorators too:

js-sdk/packages/nest/src/feature.decorator.ts

Line 36 in cf89e7d

interface FeatureProps<T extends FlagValue> {

So to me this is optional for this PR but it would be a great addition.

Sounds good, will do.

Cool, are you still planning to do it @kaushalkapasi? I can not see it yet, but you re-requested a review.
We can definitely leave it out for now if you want.

@lukas-reining I decided not to add this in for now.

Would you be able to elaborate how this would be used and how it would work differently compared to the ability to define the context (as on line 39)?

No worries!
The difference is, that the factory could use the ExecutionContext to get request information like headers or IP address and transform that to evaluation context.
This can currently only be done in the transaction context, having it here would allow e.g. to use a specific http header as context value for the specified flags only.

packages/nest/src/require-flags-enabled.decorator.ts

lukas-reining · 2025-03-25T21:14:39Z

packages/nest/src/require-flags-enabled.decorator.ts

+export const RequireFlagsEnabled = (props: RequireFlagsEnabledProps): ClassDecorator & MethodDecorator =>
+  applyDecorators(UseInterceptors(FlagsEnabledInterceptor(props)));


I think there could be value in similar function like: RequireFlagEquals.
But this could also be added in another PR.

Yeah! I opted to implement this first as the "easiest" option, a follow up would be to take a flag key and expected value combination to support String, Number and Object type flags.

Yep that makes sense to me. I think most people would use this current decorator, which could basically just be a shorthand for a RequireFlagEquals implementation. I think instead of a key/value combination though, a lambda predicate might be easier (a lambda taking the EvalutionDetails which will run to decide to run the request or not). For RequireFlagsEnabled, the lambda would just be evalutationDetails.value === true

@kaushalkapasi do you want to do this in this PR?
Because you requested reviews again but I could not find it yet.
We can also leave it out of here, but it might be really good to have here.

I haven't added the lambda function in this PR. My only concern is that it would complicate the usage of this Boolean only provider.

I would definitely add it when we build a decorator for other flag types (String, Number and Object).

Let me know if you think it should be implemented here and I'd be happy to do so.

If you do it like @toddbaert describes, RequireFlagsEnabled would simply be an alias for RequireFlagEquals with evalutationDetails.value === true.
It would not make the RequireFlagsEnabled more complicated in this case.

I would prefer to have it.

Sounds good, I'll update this implementation soon and tag you for a re-review when ready!

packages/nest/src/require-flags-enabled.decorator.ts

lukas-reining · 2025-03-25T21:32:51Z

I will have a look at what is wrong with the e2e test tomorrow @kaushalkapasi :)

toddbaert · 2025-03-27T18:43:33Z

I will have a look at what is wrong with the e2e test tomorrow @kaushalkapasi :)

@lukas-reining @kaushalkapasi

Seems to me like the test-harness git submodule was simply deleted. I've added it back in the latest commit. The e2e tests are working now but you have some small lint errors causing CI failures.

packages/nest/src/require-flags-enabled.decorator.ts

toddbaert · 2025-03-27T19:14:05Z

packages/nest/test/fixtures.ts

+  testBooleanFlag2: {
+    defaultVariant: 'default',
+    variants: { default: false, enabled: true },
+    disabled: false,
+  },


Could we add another integration test where we use a flag with a simple targeting rule, which requires an evaluation context value (which is injected in an interceptor) to be present? That would ensure that we are using a per-request context as expected in our decorator(s).

Sounds good, will add the test.

toddbaert

I have a couple questions, and one request for an additional test (please let me know if you think this is not necessary) but this looks really cool. Great work!

Happy to approve from my perspective after these are resolved.

lukas-reining · 2025-04-05T15:55:49Z

Sorry for taking time @kaushalkapasi, many of us have been at KubeCon.
Will have a look tomorrow or the day after :)

…er & endpoint access based on boolean flag values Signed-off-by: Kaushal Kapasi <[email protected]>

…s enabled decorator Signed-off-by: Kaushal Kapasi <[email protected]>

Signed-off-by: Kaushal Kapasi <[email protected]>

…text and allow for flags to change the default value for flag evaluation. move getClientForEvaluation method to utils file Signed-off-by: Kaushal Kapasi <[email protected]>

Signed-off-by: Todd Baert <[email protected]>

Signed-off-by: Kaushal Kapasi <[email protected]>

…add tests with targeting rules defined for the InMemoryProvider Signed-off-by: Kaushal Kapasi <[email protected]>

lukas-reining

It would be great if you could also add something to the README to show the feature and explain the usage, so people know it exists and how to use :)

toddbaert

Implementation looks great. Like @lukas-reining says I think we could use some docs so people know how to use this cool new feature... but I'm approving.

beeme1mr requested a review from lukas-reining March 18, 2025 21:15

toddbaert requested review from toddbaert and luizgribeiro March 19, 2025 19:15

kaushalkapasi force-pushed the feat/require-flags-decorator branch 2 times, most recently from ca912f0 to a67cc35 Compare March 25, 2025 17:59

kaushalkapasi marked this pull request as ready for review March 25, 2025 18:00

kaushalkapasi requested a review from a team as a code owner March 25, 2025 18:00

lukas-reining approved these changes Mar 25, 2025

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kaushalkapasi requested a review from lukas-reining March 26, 2025 15:54

toddbaert reviewed Mar 27, 2025

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packages/nest/src/require-flags-enabled.decorator.ts Show resolved Hide resolved

toddbaert reviewed Mar 27, 2025

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toddbaert self-requested a review March 27, 2025 19:16

toddbaert requested changes Mar 27, 2025

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kaushalkapasi force-pushed the feat/require-flags-decorator branch from aa03a3a to ba2c4d6 Compare March 31, 2025 15:53

kaushalkapasi requested a review from toddbaert March 31, 2025 15:54

kaushalkapasi and others added 7 commits April 7, 2025 09:48

feat: adds RequireFlagsEnabled decorator to allow reusable controll…

b06ca5d

…er & endpoint access based on boolean flag values Signed-off-by: Kaushal Kapasi <[email protected]>

fix: update imports for types and cleanup js docs on the require flag…

5e7dabe

…s enabled decorator Signed-off-by: Kaushal Kapasi <[email protected]>

feat: add tests for RequireFlagsEnabled decorator

eb3eb1f

Signed-off-by: Kaushal Kapasi <[email protected]>

feat: update options for RequireFlagsEnabled decorator to include con…

c2c5157

…text and allow for flags to change the default value for flag evaluation. move getClientForEvaluation method to utils file Signed-off-by: Kaushal Kapasi <[email protected]>

fixup: restore sm

bef054a

Signed-off-by: Todd Baert <[email protected]>

chore: remove unused import to fix lint errors

ce9852b

Signed-off-by: Kaushal Kapasi <[email protected]>

fix: update docs for context definition on RequireFlagsEnabledProps. …

f056ae6

…add tests with targeting rules defined for the InMemoryProvider Signed-off-by: Kaushal Kapasi <[email protected]>

kaushalkapasi force-pushed the feat/require-flags-decorator branch from ba2c4d6 to f056ae6 Compare April 7, 2025 13:49

kaushalkapasi requested a review from a team as a code owner April 7, 2025 13:49

lukas-reining reviewed Apr 7, 2025

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lukas-reining requested a review from a team April 7, 2025 14:18

toddbaert approved these changes Apr 10, 2025

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lukas-reining added 2 commits April 10, 2025 20:48

Merge branch 'main' into feat/require-flags-decorator

46b5f26

Merge branch 'main' into feat/require-flags-decorator

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feat: adds RequireFlagsEnabled decorator #1159

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		export const RequireFlagsEnabled = (props: RequireFlagsEnabledProps): ClassDecorator & MethodDecorator =>
		applyDecorators(UseInterceptors(FlagsEnabledInterceptor(props)));

feat: adds RequireFlagsEnabled decorator #1159

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feat: adds RequireFlagsEnabled decorator #1159

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kaushalkapasi commented Mar 14, 2025 • edited Loading

This PR

Notes

Follow-up Tasks

How to test

toddbaert commented Mar 20, 2025

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