Add environment vairable to randomize resolver addresses

Makefile

@@ -420,4 +420,4 @@ endef
 .PHONY: gettrivy
 gettrivy:
 	@mkdir -p $(TOOLS_BIN)
-	curl -sfL https://raw.githubusercontent.com/aquasecurity/trivy/main/contrib/install.sh | sh -s -- -b $(TOOLS_BIN) v0.38.3
+	curl -sfL https://raw.githubusercontent.com/aquasecurity/trivy/main/contrib/install.sh | sh -s -- -b $(TOOLS_BIN) v0.51.2

coherence/common.go

@@ -40,6 +40,9 @@ const (
 	// envResolverDebug enables resolver debug messages to be displayed.
 	envResolverDebug = "COHERENCE_RESOLVER_DEBUG"
 
+	// envResolverDebug enables randomization of addresses returned by resolver
+	envResolverRandomize = "COHERENCE_RESOLVER_RANDOMIZE"
+
 	// Integer.MAX_VALUE on Java
 	integerMaxValue = 2147483647
 

coherence/doc.go

@@ -69,6 +69,10 @@ If you have multiple clusters on the same port, you can also append the cluster
 
 	coherence.WithAddress("coherence:///localhost:7574/cluster2")
 
+When using the 'coherence' gRPC resolver, the addresses are always tried in the same order as they are returned from the
+Name Service lookup. The Go Client randomizes any addresses, but you can turn this off by setting the
+environment variable COHERENCE_RESOLVER_RANDOMIZER=false.
+
 To Configure SSL, you must first enable SSL on the gRPC Proxy, see [gRPC Proxy documentation] for details.
 Refer to the section on [NewSession] for more information on setting up a SSL connection on the client.
 

coherence/resolver.go

@@ -12,8 +12,10 @@ import (
 	"github.com/oracle/coherence-go-client/coherence/discovery"
 	"google.golang.org/grpc/resolver"
 	"log"
+	"math/rand"
 	"strings"
 	"sync"
+	"time"
 )
 
 const (
@@ -25,6 +27,7 @@ var (
 	resolverDebug  = func(v ...any) {
 		// noop as default debug mode
 	}
+	randomizeAddresses bool
 )
 
 type nsLookupResolverBuilder struct {
@@ -68,7 +71,16 @@ func (r *nsLookupResolver) resolve() {
 	for i, s := range grpcEndpoints {
 		addresses[i] = resolver.Address{Addr: s}
 	}
-	resolverDebug(fmt.Sprintf("resolver produced the following addresses: %v", addresses))
+
+	if randomizeAddresses {
+		// randomize the address list
+		rand.NewSource(time.Now().UnixNano())
+		rand.Shuffle(len(addresses), func(i, j int) {
+			addresses[i], addresses[j] = addresses[j], addresses[i]
+		})
+	}
+
+	resolverDebug(fmt.Sprintf("resolver produced the following addresses: %v, randomize=%v", addresses, randomizeAddresses))
 	_ = r.cc.UpdateState(resolver.State{Addresses: addresses})
 }
 

coherence/session.go

@@ -165,6 +165,10 @@ func NewSession(ctx context.Context, options ...func(session *SessionOptions)) (
 			DisconnectTimeout:  time.Duration(0) * time.Second},
 	}
 
+	if getBoolValueFromEnvVarOrDefault(envResolverRandomize, true) {
+		randomizeAddresses = true
+	}
+
 	// ensure name resolver has been registered
 	resolver.Register(&nsLookupResolverBuilder{})