add httproute weight based routing mesh conformance tests (#3827)

* add httproute weights mesh conformance tests

* gofmt

Author: LiorLieberman

conformance/tests/mesh/httproute-weight.go

@@ -0,0 +1,143 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package meshtests
+
+import (
+	"cmp"
+	"errors"
+	"fmt"
+	"math"
+	"slices"
+	"strings"
+	"sync"
+	"testing"
+
+	"golang.org/x/sync/errgroup"
+
+	"sigs.k8s.io/gateway-api/conformance/utils/echo"
+	"sigs.k8s.io/gateway-api/conformance/utils/http"
+	"sigs.k8s.io/gateway-api/conformance/utils/suite"
+	"sigs.k8s.io/gateway-api/pkg/features"
+)
+
+func init() {
+	MeshConformanceTests = append(MeshConformanceTests, MeshHTTPRouteWeight)
+}
+
+var MeshHTTPRouteWeight = suite.ConformanceTest{
+	ShortName:   "MeshHTTPRouteWeight",
+	Description: "An HTTPRoute with weighted backends",
+	Manifests:   []string{"tests/mesh/httproute-weight.yaml"},
+	Features: []features.FeatureName{
+		features.SupportMesh,
+		features.SupportHTTPRoute,
+	},
+	Test: func(t *testing.T, s *suite.ConformanceTestSuite) {
+		client := echo.ConnectToApp(t, s, echo.MeshAppEchoV1)
+
+		t.Run("Requests should have a distribution that matches the weight", func(t *testing.T) {
+			host := "echo"
+			expected := http.ExpectedResponse{
+				Request:   http.Request{Path: "/", Host: host},
+				Response:  http.Response{StatusCode: 200},
+				Namespace: "gateway-conformance-mesh",
+			}
+
+			// Assert request succeeds before doing our distribution check
+			client.MakeRequestAndExpectEventuallyConsistentResponse(t, expected, s.TimeoutConfig)
+			for i := 0; i < 10; i++ {
+				if err := testDistribution(t, client, expected); err != nil {
+					t.Logf("Traffic distribution test failed (%d/10): %s", i+1, err)
+				} else {
+					return
+				}
+			}
+			t.Fatal("Weighted distribution tests failed")
+		})
+	},
+}
+
+func testDistribution(t *testing.T, client echo.MeshPod, expected http.ExpectedResponse) error {
+	const (
+		concurrentRequests  = 10
+		tolerancePercentage = 0.05
+		totalRequests       = 500.0
+	)
+	var (
+		g               errgroup.Group
+		seenMutex       sync.Mutex
+		seen            = make(map[string]float64, 2 /* number of backends */)
+		expectedWeights = map[string]float64{
+			"echo-v1": 0.7,
+			"echo-v2": 0.3,
+		}
+	)
+	g.SetLimit(concurrentRequests)
+	for i := 0.0; i < totalRequests; i++ {
+		g.Go(func() error {
+			_, cRes, err := client.CaptureRequestResponseAndCompare(t, expected)
+			if err != nil {
+				return fmt.Errorf("failed: %w", err)
+			}
+
+			seenMutex.Lock()
+			defer seenMutex.Unlock()
+
+			for expectedBackend := range expectedWeights {
+				if strings.HasPrefix(cRes.Hostname, expectedBackend) {
+					seen[expectedBackend]++
+					return nil
+				}
+			}
+
+			return fmt.Errorf("request was handled by an unexpected pod %q", cRes.Hostname)
+		})
+	}
+
+	if err := g.Wait(); err != nil {
+		return fmt.Errorf("error while sending requests: %w", err)
+	}
+
+	var errs []error
+	if len(seen) != 2 {
+		errs = append(errs, fmt.Errorf("expected only two backends to receive traffic"))
+	}
+
+	for wantBackend, wantPercent := range expectedWeights {
+		gotCount, ok := seen[wantBackend]
+
+		if !ok && wantPercent != 0.0 {
+			errs = append(errs, fmt.Errorf("expect traffic to hit backend %q - but none was received", wantBackend))
+			continue
+		}
+
+		gotPercent := gotCount / totalRequests
+
+		if math.Abs(gotPercent-wantPercent) > tolerancePercentage {
+			errs = append(errs, fmt.Errorf("backend %q weighted traffic of %v not within tolerance %v (+/-%f)",
+				wantBackend,
+				gotPercent,
+				wantPercent,
+				tolerancePercentage,
+			))
+		}
+	}
+	slices.SortFunc(errs, func(a, b error) int {
+		return cmp.Compare(a.Error(), b.Error())
+	})
+	return errors.Join(errs...)
+}

conformance/tests/mesh/httproute-weight.yaml

@@ -0,0 +1,19 @@
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: mesh-weighted-backends
+  namespace: gateway-conformance-mesh
+spec:
+  parentRefs:
+  - group: ""
+    kind: Service
+    name: echo
+    port: 80
+  rules:
+  - backendRefs:
+    - name: echo-v1
+      port: 8080
+      weight: 70
+    - name: echo-v2
+      port: 8080
+      weight: 30

conformance/utils/echo/pod.go

@@ -105,6 +105,9 @@ func makeRequest(t *testing.T, exp *http.ExpectedResponse) []string {
 }
 
 func compareRequest(exp http.ExpectedResponse, resp Response) error {
+	if exp.ExpectedRequest == nil {
+		exp.ExpectedRequest = &http.ExpectedRequest{}
+	}
 	wantReq := exp.ExpectedRequest
 	wantResp := exp.Response
 	if fmt.Sprint(wantResp.StatusCode) != resp.Code {
@@ -220,3 +223,19 @@ func ConnectToAppInNamespace(t *testing.T, s *suite.ConformanceTestSuite, app Me
 		rcfg:      s.RestConfig,
 	}
 }
+
+func (m *MeshPod) CaptureRequestResponseAndCompare(t *testing.T, exp http.ExpectedResponse) ([]string, Response, error) {
+	req := makeRequest(t, &exp)
+
+	resp, err := m.request(req)
+	if err != nil {
+		tlog.Logf(t, "Request %v failed, not ready yet: %v", req, err.Error())
+		return []string{}, Response{}, err
+	}
+	tlog.Logf(t, "Got resp %v", resp)
+	if err := compareRequest(exp, resp); err != nil {
+		tlog.Logf(t, "Response expectation failed for request: %v  not ready yet: %v", req, err)
+		return []string{}, Response{}, err
+	}
+	return req, resp, nil
+}