feat: Implement multiprovider #354

jblacker · 2025-05-15T02:32:09Z

This PR

Implements the Multiprovider specified in "Appendix A: Included Utilities" of the OpenFeature Spec. This implementation is an improvement upon what I initially implemented in the go-sdk-contrib repository here & here.

This includes implementations for all three strategies described in the spec along with some common functions. Unlike my original implementation this includes full support for hooks & event handling from the included handlers.

Related Issues

open-feature/go-sdk-contrib#599

Notes

I reimplemented this here from the go-sdk-contrib repo on suggestion of other members. This includes the refactoring improvements that I was mentioning in discussions on my open PR over there.

This PR is currently in draft because it is built on top of the exported mocks in order to provide a full unit test suite.

Follow-up Tasks

e2e / Gherkin tests should be written
Minor clean up & improvements

How to test

Create an application and pass a multiprovider to the OpenFeature SDK that includes 2 or more providers. Verify that the results are as expected per the selected strategy.

- Also updated the generated filenames to remove the test prefix allowing them to be exportable - Added a sed command to prepend the build tag "testtools" to the mock files - Updated test commands to include the "testtools" build tag - Added step to delete the backups generated by sed Signed-off-by: Jordan Blacker <[email protected]>

- Remove legacy mocks - Update Makefile Signed-off-by: Jordan Blacker <[email protected]>

Signed-off-by: Jordan Blacker <[email protected]>

… reports Signed-off-by: Jordan Blacker <[email protected]>

Signed-off-by: Jordan Blacker <[email protected]>

erka · 2025-06-03T10:04:49Z

Hey @jblacker.

Is there any road block to move this forward? Do you need any help?

jblacker · 2025-06-03T12:28:49Z

I've actually been on vacation. I'm going to pick back up on this tomorrow.

Signed-off-by: Jordan Blacker <[email protected]>

This is due to the fact that slog.DiscardHandler is not introduced until go 1.24 Signed-off-by: Jordan Blacker <[email protected]>

Signed-off-by: Jordan Blacker <[email protected]>

This reverts commit ea29d0f. Signed-off-by: Jordan Blacker <[email protected]>

codecov · 2025-06-04T23:55:02Z

Codecov Report

❌ Patch coverage is 72.35495% with 243 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.79%. Comparing base (53a89f3) to head (f722ff3).

Files with missing lines	Patch %	Lines
openfeature/multiprovider/multiprovider.go	62.94%	121 Missing and 5 partials ⚠️
openfeature/multiprovider/isolation.go	61.16%	82 Missing and 5 partials ⚠️
openfeature/multiprovider/comparison_strategy.go	89.13%	17 Missing and 3 partials ⚠️
openfeature/multiprovider/strategies.go	88.37%	8 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #354      +/-   ##
==========================================
- Coverage   85.69%   80.79%   -4.90%     
==========================================
  Files          20       27       +7     
  Lines        1433     2312     +879     
==========================================
+ Hits         1228     1868     +640     
- Misses        184      408     +224     
- Partials       21       36      +15

Flag	Coverage Δ
e2e	`80.79% <72.35%> (-4.90%)`	⬇️
unit	`80.79% <72.35%> (-4.90%)`	⬇️

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sahidvelji · 2025-08-22T22:56:57Z

I'm going to be away until Sept 2nd, so I likely won't have the time to review thoroughly until then.

Signed-off-by: Jordan Blacker <[email protected]>

sahidvelji · 2025-09-05T02:15:42Z

openfeature/multiprovider/comparison_strategy.go

+
+// NewComparisonStrategy creates a new instance of ComparisonStrategy. The fallback provider specified is called when
+// there is a comparison failure -- prior to returning a default result. The Comparator parameter is optional and nil
+// can be passed as long as ObjectEvaluation is never called. Unless the `alwaysUseCustom` parameter is true the default


I don't see an alwaysUseCustom parameter here. Go doc comments also don't do anything special with backticks, so you should avoid them.

You're right. That was removed during some refactoring, but I forgot to update the docs. I'll get this cleaned up. The backticks is just a bad habit from markdown. I'll clean that up too throughout.

sahidvelji · 2025-09-05T02:18:09Z

openfeature/multiprovider/comparison_strategy.go

+// there is a comparison failure -- prior to returning a default result. The Comparator parameter is optional and nil
+// can be passed as long as ObjectEvaluation is never called. Unless the `alwaysUseCustom` parameter is true the default
+// comparisons built into Go will be used. The custom Comparator will only be used for ObjectEvaluation. However, if the
+// parameter is set to true the custom Comparator will always be used regardless of evaluation type. If ObjectEvaluation


Please use doc links to refer to any exported identifier, like [Comparator] and [of.FeatureProvider.ObjectEvaluation]. See https://tip.golang.org/doc/comment#doclinks

Updated throughout.

sahidvelji · 2025-09-05T02:21:50Z

openfeature/multiprovider/strategies.go

+	// StrategyFirstMatch First provider whose response that is not FlagNotFound will be returned. This is executed
+	// sequentially, and not in parallel.
+	StrategyFirstMatch EvaluationStrategy = "strategy-first-match"
+	// StrategyFirstSuccess First provider response that is not an error will be returned. This is executed sequentially


Suggested change

// StrategyFirstSuccess First provider response that is not an error will be returned. This is executed sequentially

// StrategyFirstSuccess returns the first provider response that is not an error. This is executed sequentially.

Write the other doc comments in a similar fashion. They should read like sentences and the first word after the identifier being documented should not be capitalized.

Ack, I'll update throughout

sahidvelji · 2025-09-05T02:23:33Z

openfeature/multiprovider/strategies.go

+	ReasonAggregated         of.Reason = "AGGREGATED"
+	ReasonAggregatedFallback of.Reason = "AGGREGATED_FALLBACK"


This should be in its own const () block since it's not an [EvaluationStrategy].

sahidvelji · 2025-09-05T02:23:53Z

openfeature/multiprovider/strategies.go

+	ReasonAggregated         of.Reason = "AGGREGATED"
+	ReasonAggregatedFallback of.Reason = "AGGREGATED_FALLBACK"
+
+	ErrAggregationNotAllowedText = "object evaluation not allowed for non-comparable types without custom comparable func"


This should be in its own const () block since it's not an [EvaluationStrategy].

openfeature/multiprovider/strategies.go

openfeature/multiprovider/multiprovider.go

sahidvelji · 2025-09-05T02:28:12Z

openfeature/multiprovider/multiprovider.go

+// AsNamedProviderSlice Converts the map into a slice of NamedProvider instances
+func toNamedProviderSlice(m ProviderMap) []*NamedProvider {


Update the doc comment to match the function name

sahidvelji · 2025-09-05T02:37:43Z

Left some more comments. I didn't get time to look at the whole PR, so I may have more comments later.

Signed-off-by: Jordan Blacker <[email protected]>

Co-authored-by: Sahid Velji <[email protected]> Signed-off-by: Jordan Blacker <[email protected]>

lukas-reining · 2025-09-23T09:40:35Z

Hey @open-feature/sdk-golang-maintainers can we get some reviews done here?
It would be great to have the multi provider for Go available.

jblacker added 16 commits May 7, 2025 15:55

chore: generate new mocks

6b6ba4c

- Remove legacy mocks - Update Makefile Signed-off-by: Jordan Blacker <[email protected]>

fix: Update test imports to use ubermock & newly generated mocks

5195e80

Signed-off-by: Jordan Blacker <[email protected]>

chore: go mod tidy

db9cc14

Signed-off-by: Jordan Blacker <[email protected]>

doc: Add information about using exported mocks

cedd7da

Signed-off-by: Jordan Blacker <[email protected]>

build: Update ci to include testtool tag for running tests

8904308

Signed-off-by: Jordan Blacker <[email protected]>

build: Update makefile to include build-tags for linting

26eff7b

Signed-off-by: Jordan Blacker <[email protected]>

fix: downgrade ubermock to prevent bumping go version

cf0c504

Signed-off-by: Jordan Blacker <[email protected]>

fix: Add codecov.yml to prevent mocks from being included in coverage…

c1e6b5c

… reports Signed-off-by: Jordan Blacker <[email protected]>

feat: Add error types

1add33d

Signed-off-by: Jordan Blacker <[email protected]>

feat: add HookIsolator helper types

af389cd

Signed-off-by: Jordan Blacker <[email protected]>

feat: add common components for strategies

8319018

Signed-off-by: Jordan Blacker <[email protected]>

chore: go mod tidy

b1bfc53

Signed-off-by: Jordan Blacker <[email protected]>

feat: Implement strategies

8ec1e9e

Signed-off-by: Jordan Blacker <[email protected]>

feat: generate Strategy mock

a952ad5

Signed-off-by: Jordan Blacker <[email protected]>

feat: Implement MultiProvider API

4560a8f

Signed-off-by: Jordan Blacker <[email protected]>

jblacker changed the title ~~Implement multiprovider~~ feat: Implement multiprovider May 15, 2025

This was referenced May 15, 2025

feat: Complete Implementation of Multi-Provider open-feature/go-sdk-contrib#678

Closed

Implement Multi-Provider open-feature/go-sdk-contrib#599

Open

Merge branch 'main' into implement-multiprovider

b638653

Signed-off-by: Jordan Blacker <[email protected]>

jblacker and others added 7 commits June 4, 2025 17:05

Merge branch 'main' into implement-multiprovider

d4463cc

Signed-off-by: Jordan Blacker <[email protected]>

chore: go mod tidy

ea29d0f

Signed-off-by: Jordan Blacker <[email protected]>

fix: Implement DiscardHandler for slog

f0dfc05

This is due to the fact that slog.DiscardHandler is not introduced until go 1.24 Signed-off-by: Jordan Blacker <[email protected]>

chore: lint everything

e401753

Signed-off-by: Jordan Blacker <[email protected]>

refactor: Made discard handler private

9b230c0

Signed-off-by: Jordan Blacker <[email protected]>

fix: eliminate potential race conditions per go test -race flag

f25b8ca

Signed-off-by: Jordan Blacker <[email protected]>

Revert "chore: go mod tidy"

b176b03

This reverts commit ea29d0f. Signed-off-by: Jordan Blacker <[email protected]>

jblacker requested review from toddbaert and sahidvelji August 22, 2025 21:13

jblacker and others added 2 commits September 4, 2025 15:06

Merge branch 'main' into implement-multiprovider

c49c65f

Signed-off-by: Jordan Blacker <[email protected]>

chore: go mod tidy

76cf8b7

Signed-off-by: Jordan Blacker <[email protected]>

jblacker force-pushed the implement-multiprovider branch from 304831b to 76cf8b7 Compare September 4, 2025 19:09

sahidvelji reviewed Sep 5, 2025

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jblacker and others added 9 commits September 7, 2025 14:40

Merge branch 'main' into implement-multiprovider

7ffa4b0

doc: Cleanup NewComparisonStrategy docs

2d38d30

Signed-off-by: Jordan Blacker <[email protected]>

doc: clean up docs in multiprovider top level

f20f8bd

Signed-off-by: Jordan Blacker <[email protected]>

refactor: Reorganize constants & update more docs

0a3d47f

Signed-off-by: Jordan Blacker <[email protected]>

doc: Update strategy docs

ba1a6ce

Signed-off-by: Jordan Blacker <[email protected]>

fix: Add missing WithCustomComparator Option

dc1a7f0

Signed-off-by: Jordan Blacker <[email protected]>

docs: Update documentation formatting throughout

ed6f308

Signed-off-by: Jordan Blacker <[email protected]>

refactor: Don't export configuration object

e614107

Signed-off-by: Jordan Blacker <[email protected]>

Update openfeature/multiprovider/strategies.go

f722ff3

Co-authored-by: Sahid Velji <[email protected]> Signed-off-by: Jordan Blacker <[email protected]>

jblacker requested a review from sahidvelji September 8, 2025 18:17

lukas-reining requested review from a team September 23, 2025 09:40

lukas-reining mentioned this pull request Sep 23, 2025

feat: add feature flag support openfga/openfga#2708

Draft

4 tasks

	// StrategyFirstSuccess First provider response that is not an error will be returned. This is executed sequentially
	// StrategyFirstSuccess returns the first provider response that is not an error. This is executed sequentially.

		ReasonAggregated of.Reason = "AGGREGATED"
		ReasonAggregatedFallback of.Reason = "AGGREGATED_FALLBACK"

		// AsNamedProviderSlice Converts the map into a slice of NamedProvider instances
		func toNamedProviderSlice(m ProviderMap) []*NamedProvider {

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Related Issues

Notes

Follow-up Tasks

How to test

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