fix(Kong#5658): handle edge cases for tag filtering detection

Signed-off-by: Hoang Quoc Trung <trung.hoang@pricehubble.com>

internal/dataplane/sendconfig/kong.go

@@ -2,6 +2,7 @@ package sendconfig
 
 import (
 	"context"
+	"errors"
 	"fmt"
 
 	"github.com/blang/semver/v4"
@@ -11,6 +12,11 @@ import (
 	"github.com/kong/kubernetes-ingress-controller/v3/internal/adminapi"
 )
 
+var (
+	ErrAdminAPIUnreachable  = errors.New("Kong Admin API is unreachable")
+	ErrAdminAPITagsDisabled = errors.New("Kong Admin API does not support tags")
+)
+
 // Config gathers parameters that are needed for sending configuration to Kong Admin APIs.
 type Config struct {
 	// Currently, this assumes that all underlying clients are using the same version
@@ -47,13 +53,18 @@ func (c *Config) Init(
 	ctx context.Context,
 	logger logr.Logger,
 	kongClients []*adminapi.Client,
-) {
+) error {
 	if err := tagsFilteringEnabled(ctx, kongClients); err != nil {
-		logger.Error(err, "Tag filtering disabled")
-		c.FilterTags = nil
-	} else {
-		logger.Info("Tag filtering enabled", "tags", c.FilterTags)
+		if errors.Is(err, ErrAdminAPITagsDisabled) {
+			logger.Error(err, "Tag filtering disabled")
+			c.FilterTags = nil
+			return nil
+		}
+		return err
 	}
+
+	logger.Info("Tag filtering enabled", "tags", c.FilterTags)
+	return nil
 }
 
 func tagsFilteringEnabled(ctx context.Context, kongClients []*adminapi.Client) error {
@@ -62,11 +73,12 @@ func tagsFilteringEnabled(ctx context.Context, kongClients []*adminapi.Client) e
 		cl := cl
 		errg.Go(func() error {
 			ok, err := cl.AdminAPIClient().Tags.Exists(ctx)
-			if err != nil {
-				return fmt.Errorf("Kong Admin API (%s) does not support tags: %w", cl.BaseRootURL(), err)
-			}
+
 			if !ok {
-				return fmt.Errorf("Kong Admin API (%s) does not support tags", cl.BaseRootURL())
+				if err == nil {
+					return fmt.Errorf("%w", ErrAdminAPIUnreachable)
+				}
+				return fmt.Errorf("%w: %w", ErrAdminAPIUnreachable, err)
 			}
 			return nil
 		})

internal/manager/run.go

@@ -123,7 +123,9 @@ func Run(
 		ExpressionRoutes:           dpconf.ShouldEnableExpressionRoutes(routerFlavor),
 		SanitizeKonnectConfigDumps: featureGates.Enabled(featuregates.SanitizeKonnectConfigDumps),
 	}
-	kongConfig.Init(ctx, setupLog, initialKongClients)
+	if err := kongConfig.Init(ctx, setupLog, initialKongClients); err != nil {
+		return fmt.Errorf("unable to check if tags filtering is enabled: %w", err)
+	}
 
 	setupLog.Info("Configuring and building the controller manager")
 	managerOpts, err := setupManagerOptions(ctx, setupLog, c, dbMode)