platform agnostic lb ep hash

changelog/v1.18.0-rc2/platform-agnostic-lbephash.yaml

@@ -0,0 +1,6 @@
+changelog:
+  - type: NON_USER_FACING
+    description: >-
+      Don't use xor or native endian-ness when generating hashes.
+      This creates difficulty reproducing tests on different machines
+      where the hashes end up in goldenfiles.

projects/gateway2/krtcollections/endpoints.go

@@ -170,8 +170,8 @@ func hashEndpoints(l PodLocality, emd EndpointWithMd) uint64 {
 func hash(a, b uint64) uint64 {
 	hasher := fnv.New64a()
 	var buf [16]byte
-	binary.NativeEndian.PutUint64(buf[:8], a)
-	binary.NativeEndian.PutUint64(buf[8:], b)
+	binary.LittleEndian.PutUint64(buf[:8], a)
+	binary.LittleEndian.PutUint64(buf[8:], b)
 	hasher.Write(buf[:])
 	return hasher.Sum64()
 }

projects/gateway2/krtcollections/endpoints_test.go

@@ -2,6 +2,8 @@ package krtcollections
 
 import (
 	"context"
+	"crypto/sha256"
+	"encoding/binary"
 	"testing"
 
 	envoy_config_core_v3 "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
@@ -131,7 +133,6 @@ func TestEndpointsForUpstreamOrderDoesntMatter(t *testing.T) {
 		Zone:   "zone2",
 	}, emd2)
 	g.Expect(result1.Equals(*result4)).To(BeFalse(), "not expected %v, got %v", result1, result2)
-
 }
 
 func TestEndpointsForUpstreamWithDiscoveredUpstream(t *testing.T) {
@@ -235,11 +236,23 @@ func TestEndpointsForUpstreamWithDiscoveredUpstream(t *testing.T) {
 		Zone:   "zone",
 	}, emd2)
 
-	h1 := result1.LbEpsEqualityHash ^ result2.LbEpsEqualityHash
-	h2 := result3.LbEpsEqualityHash ^ result4.LbEpsEqualityHash
+	h1 := combineHashes(result1.LbEpsEqualityHash, result2.LbEpsEqualityHash)
+	h2 := combineHashes(result3.LbEpsEqualityHash, result4.LbEpsEqualityHash)
 
 	g.Expect(h1).NotTo(Equal(h2), "not expected %v, got %v", h1, h2)
+}
+
+func combineHashes(hash1, hash2 uint64) uint64 {
+	// Create a buffer for the combined hashes
+	buf := make([]byte, 16)
+	binary.LittleEndian.PutUint64(buf[:8], hash1)
+	binary.LittleEndian.PutUint64(buf[8:], hash2)
 
+	// Hash the combined buffer
+	sum := sha256.Sum256(buf)
+
+	// Return the first 8 bytes of the hash as a uint64
+	return binary.LittleEndian.Uint64(sum[:8])
 }
 
 func TestEndpoints(t *testing.T) {
@@ -960,5 +973,4 @@ func TestEndpoints(t *testing.T) {
 			g.Expect(eps.Equals(*res)).To(BeTrue(), "expected %v, got %v", res, eps)
 		})
 	}
-
 }

projects/gateway2/proxy_syncer/cla.go

@@ -1,6 +1,7 @@
 package proxy_syncer
 
 import (
+	"encoding/binary"
 	"fmt"
 	"hash/fnv"
 
@@ -129,18 +130,23 @@ func NewPerClientEnvoyEndpoints(logger *zap.Logger, dbg *krt.DebugHandler, uccs
 }
 
 func PrioritizeEndpoints(logger *zap.Logger, destrule *DestinationRuleWrapper, ep krtcollections.EndpointsForUpstream, ucc krtcollections.UniqlyConnectedClient) UccWithEndpoints {
-	var additionalHash uint64
 	var priorityInfo *PriorityInfo
 
+	updatedHash := ep.LbEpsEqualityHash
 	if destrule != nil {
 		trafficPolicy := getTraficPolicy(destrule, ep.Port)
 		localityLb := getLocalityLbSetting(trafficPolicy)
 		if localityLb != nil {
 			priorityInfo = getPriorityInfoFromDestrule(localityLb)
 			hasher := fnv.New64()
+
+			oldHash := make([]byte, 8)
+			binary.LittleEndian.PutUint64(oldHash, updatedHash)
+			hasher.Write(oldHash)
+
 			hasher.Write([]byte(destrule.UID))
 			hasher.Write([]byte(fmt.Sprintf("%v", destrule.Generation)))
-			additionalHash = hasher.Sum64()
+			updatedHash = hasher.Sum64()
 		}
 	}
 	lbInfo := LoadBalancingInfo{
@@ -153,7 +159,7 @@ func PrioritizeEndpoints(logger *zap.Logger, destrule *DestinationRuleWrapper, e
 	return UccWithEndpoints{
 		Client:        ucc,
 		Endpoints:     resource.NewEnvoyResource(cla),
-		EndpointsHash: ep.LbEpsEqualityHash ^ additionalHash,
+		EndpointsHash: updatedHash,
 		endpointsName: ep.ResourceName(),
 	}
 }