refactor(kit/feature): remove target logic; expose bykey (#17949)

* refactor(kit/feature): remove target logic; expose bykey

* refactor(kit/feature): un-variadic-ify bykey arg

cmd/influxd/launcher/launcher.go

@@ -906,6 +906,7 @@ func (m *Launcher) run(ctx context.Context) (err error) {
 		WriteEventRecorder:              infprom.NewEventRecorder("write"),
 		QueryEventRecorder:              infprom.NewEventRecorder("query"),
 		Flagger:                         flagger,
+		FlagsHandler:                    feature.NewFlagsHandler(kithttp.ErrorHandler(0), feature.ByKey),
 	}
 
 	m.reg.MustRegister(m.apibackend.PrometheusCollectors()...)

http/api_handler.go

@@ -84,6 +84,7 @@ type APIBackend struct {
 	NotificationRuleStore           influxdb.NotificationRuleStore
 	NotificationEndpointService     influxdb.NotificationEndpointService
 	Flagger                         feature.Flagger
+	FlagsHandler                    http.Handler
 }
 
 // PrometheusCollectors exposes the prometheus collectors associated with an APIBackend.
@@ -205,7 +206,7 @@ func NewAPIHandler(b *APIBackend, opts ...APIHandlerOptFn) *APIHandler {
 	userHandler := NewUserHandler(b.Logger, userBackend)
 	h.Mount(prefixMe, userHandler)
 	h.Mount(prefixUsers, userHandler)
-	h.Mount("/api/v2/flags", serveFlagsHandler(b.HTTPErrorHandler))
+	h.Mount("/api/v2/flags", b.FlagsHandler)
 
 	variableBackend := NewVariableBackend(b.Logger.With(zap.String("handler", "variable")), b)
 	variableBackend.VariableService = authorizer.NewVariableService(b.VariableService)
@@ -281,16 +282,3 @@ func serveLinksHandler(errorHandler influxdb.HTTPErrorHandler) http.Handler {
 	}
 	return http.HandlerFunc(fn)
 }
-
-func serveFlagsHandler(errorHandler influxdb.HTTPErrorHandler) http.Handler {
-	fn := func(w http.ResponseWriter, r *http.Request) {
-		var (
-			ctx   = r.Context()
-			flags = feature.ExposedFlagsFromContext(ctx)
-		)
-		if err := encodeResponse(ctx, w, http.StatusOK, flags); err != nil {
-			errorHandler.HandleHTTPError(ctx, err, w)
-		}
-	}
-	return http.HandlerFunc(fn)
-}

kit/feature/feature.go

@@ -51,18 +51,19 @@ func FlagsFromContext(ctx context.Context) map[string]interface{} {
 	return v
 }
 
+type ByKeyFn func(string) (Flag, bool)
+
 // ExposedFlagsFromContext returns the filtered map of exposed  flags attached
 // to the context by Annotate, or nil if none is found.
-func ExposedFlagsFromContext(ctx context.Context) map[string]interface{} {
+func ExposedFlagsFromContext(ctx context.Context, byKey ByKeyFn) map[string]interface{} {
 	m := FlagsFromContext(ctx)
-
 	if m == nil {
 		return nil
 	}
 
 	filtered := make(map[string]interface{})
 	for k, v := range m {
-		if flag := byKey[k]; flag != nil && flag.Expose() {
+		if flag, found := byKey(k); found && flag.Expose() {
 			filtered[k] = v
 		}
 	}
@@ -131,3 +132,9 @@ func (*defaultFlagger) Flags(_ context.Context, flags ...Flag) (map[string]inter
 func Flags() []Flag {
 	return all
 }
+
+// ByKey returns the Flag corresponding to the given key.
+func ByKey(k string) (Flag, bool) {
+	v, found := byKey[k]
+	return v, found
+}

kit/feature/middleware.go

@@ -1,8 +1,10 @@
 package feature
 
 import (
+	"encoding/json"
 	"net/http"
 
+	"github.com/influxdata/influxdb/v2"
 	"go.uber.org/zap"
 )
 
@@ -41,3 +43,20 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		h.next.ServeHTTP(w, r)
 	}
 }
+
+// NewFlagsHandler returns a handler that returns the map of computed feature flags on the request context.
+func NewFlagsHandler(errorHandler influxdb.HTTPErrorHandler, byKey ByKeyFn) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.WriteHeader(http.StatusOK)
+
+		var (
+			ctx   = r.Context()
+			flags = ExposedFlagsFromContext(ctx, byKey)
+		)
+		if err := json.NewEncoder(w).Encode(flags); err != nil {
+			errorHandler.HandleHTTPError(ctx, err, w)
+		}
+	}
+	return http.HandlerFunc(fn)
+}

kit/feature/override/override.go

@@ -20,7 +20,7 @@ func Make(m map[string]string) (Flagger, error) {
 	}, nil
 }
 
-// Flags returns a map of default values. It never returns an error.
+// Flags returns a map of default values with overrides applied. It never returns an error.
 func (f Flagger) Flags(_ context.Context, flags ...feature.Flag) (map[string]interface{}, error) {
 	if len(flags) == 0 {
 		flags = feature.Flags()

kit/feature/target.go

@@ -1,68 +0,0 @@
-package feature
-
-import (
-	"context"
-	"errors"
-	"fmt"
-
-	"github.com/influxdata/influxdb/v2"
-	icontext "github.com/influxdata/influxdb/v2/context"
-)
-
-var ErrMissingTargetInfo = errors.New("unable to determine any user or org IDs from authorizer on context")
-
-// Target against which to match a feature flag rule.
-type Target struct {
-	// UserID to Target.
-	UserID influxdb.ID
-	// OrgIDs to Target.
-	OrgIDs []influxdb.ID
-}
-
-// MakeTarget returns a populated feature flag Target for the given environment,
-// including user and org information from the provided context, if available.
-//
-// If the authorizer on the context provides a user ID, it is used to fetch associated org IDs.
-// If a user ID is not provided, an org ID is taken directly off the authorizer if possible.
-// If no user or org information can be determined, a sentinel error is returned.
-func MakeTarget(ctx context.Context, urms influxdb.UserResourceMappingService) (Target, error) {
-	auth, err := icontext.GetAuthorizer(ctx)
-	if err != nil {
-		return Target{}, ErrMissingTargetInfo
-	}
-	userID := auth.GetUserID()
-
-	var orgIDs []influxdb.ID
-	if userID.Valid() {
-		orgIDs, err = fromURMs(ctx, userID, urms)
-		if err != nil {
-			return Target{}, err
-		}
-	} else if a, ok := auth.(*influxdb.Authorization); ok {
-		orgIDs = []influxdb.ID{a.OrgID}
-	} else {
-		return Target{}, ErrMissingTargetInfo
-	}
-
-	return Target{
-		UserID: userID,
-		OrgIDs: orgIDs,
-	}, nil
-}
-
-func fromURMs(ctx context.Context, userID influxdb.ID, urms influxdb.UserResourceMappingService) ([]influxdb.ID, error) {
-	m, _, err := urms.FindUserResourceMappings(ctx, influxdb.UserResourceMappingFilter{
-		UserID:       userID,
-		ResourceType: influxdb.OrgsResourceType,
-	})
-	if err != nil {
-		return nil, fmt.Errorf("finding organization mappings for user %s: %v", userID, err)
-	}
-
-	orgIDs := make([]influxdb.ID, 0, len(m))
-	for _, o := range m {
-		orgIDs = append(orgIDs, o.ResourceID)
-	}
-
-	return orgIDs, nil
-}