MM-29709 Client side feature flags (#16212)

* Client side feature flags.

* Fix test.

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

config/client.go

@@ -334,5 +334,9 @@ func GenerateLimitedClientConfig(c *model.Config, telemetryID string, license *m
 		}
 	}
 
+	for key, value := range featureFlagsToMap(c.FeatureFlags) {
+		props["FeatureFlag"+key] = value
+	}
+
 	return props
 }

config/client_test.go

@@ -257,6 +257,19 @@ func TestGetLimitedClientConfig(t *testing.T) {
 				"PasswordRequireSymbol":    "false",
 			},
 		},
+		{
+			"Feature Flags",
+			&model.Config{
+				FeatureFlags: &model.FeatureFlags{
+					TestFeature: "myvalue",
+				},
+			},
+			"",
+			nil,
+			map[string]string{
+				"FeatureFlagTestFeature": "myvalue",
+			},
+		},
 	}
 
 	for _, testCase := range testCases {

config/feature_flags.go

@@ -88,6 +88,24 @@ func featureFlagsFromMap(featuresMap map[string]string, baseFeatureFlags model.F
 	return baseFeatureFlags
 }
 
+// featureFlagsToMap returns the feature flags as a map[string]string
+// Currently assumes that all feature flags are strings for now.
+func featureFlagsToMap(featureFlags *model.FeatureFlags) map[string]string {
+	refStructVal := reflect.ValueOf(*featureFlags)
+	refStructType := reflect.TypeOf(*featureFlags)
+	ret := make(map[string]string)
+	for i := 0; i < refStructVal.NumField(); i++ {
+		refFieldVal := refStructVal.Field(i)
+		refFieldType := refStructType.Field(i)
+		if !refFieldVal.IsValid() {
+			continue
+		}
+		ret[refFieldType.Name] = refFieldVal.String()
+	}
+
+	return ret
+}
+
 func getStructFields(s interface{}) []string {
 	structType := reflect.TypeOf(s)
 	fieldNames := make([]string, 0, structType.NumField())

config/feature_flags_test.go

@@ -73,3 +73,27 @@ func TestFeatureFlagsFromMap(t *testing.T) {
 		})
 	}
 }
+
+func TestFeatureFlagsToMap(t *testing.T) {
+	for name, tc := range map[string]struct {
+		Flags            model.FeatureFlags
+		TestFeatureValue string
+	}{
+		"empty": {
+			TestFeatureValue: "",
+			Flags:            model.FeatureFlags{},
+		},
+		"simple value": {
+			TestFeatureValue: "expectedvalue",
+			Flags:            model.FeatureFlags{TestFeature: "expectedvalue"},
+		},
+		"empty value": {
+			TestFeatureValue: "",
+			Flags:            model.FeatureFlags{TestFeature: ""},
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			require.Equal(t, tc.TestFeatureValue, featureFlagsToMap(&tc.Flags)["TestFeature"])
+		})
+	}
+}