Adding session affinity support through loadbalancer distribution type

hcn/hcn.go

@@ -179,6 +179,15 @@ func AclSupportForProtocol252Supported() error {
 	return platformDoesNotSupportError("HNS ACL Policies to support protocol 252 for VXLAN")
 }
 
+// SessionAffinitySupported returns an error if the HCN version does not support Session Affinity.
+func SessionAffinitySupported() error {
+	supported := GetSupportedFeatures()
+	if supported.SessionAffinity {
+		return nil
+	}
+	return platformDoesNotSupportError("Session Affinity")
+}
+
 // RequestType are the different operations performed to settings.
 // Used to update the settings of Endpoint/Namespace objects.
 type RequestType string

hcn/hcnglobals.go

@@ -49,6 +49,8 @@ var (
 		VersionRange{MinVersion: Version{Major: 9, Minor: 3}, MaxVersion: Version{Major: 9, Minor: math.MaxInt32}},
 		VersionRange{MinVersion: Version{Major: 10, Minor: 4}, MaxVersion: Version{Major: math.MaxInt32, Minor: math.MaxInt32}},
 	}
+	// HNS 11.10 allows for session affinity for loadbalancing
+	SessionAffinityVersion = VersionRanges{VersionRange{MinVersion: Version{Major: 11, Minor: 10}, MaxVersion: Version{Major: math.MaxInt32, Minor: math.MaxInt32}}}
 )
 
 // GetGlobals returns the global properties of the HCN Service.

hcn/hcnloadbalancer.go

@@ -10,10 +10,11 @@ import (
 
 // LoadBalancerPortMapping is associated with HostComputeLoadBalancer
 type LoadBalancerPortMapping struct {
-	Protocol     uint32                       `json:",omitempty"` // EX: TCP = 6, UDP = 17
-	InternalPort uint16                       `json:",omitempty"`
-	ExternalPort uint16                       `json:",omitempty"`
-	Flags        LoadBalancerPortMappingFlags `json:",omitempty"`
+	Protocol         uint32                       `json:",omitempty"` // EX: TCP = 6, UDP = 17
+	InternalPort     uint16                       `json:",omitempty"`
+	ExternalPort     uint16                       `json:",omitempty"`
+	DistributionType LoadBalancerDistribution     `json:",omitempty"` // EX: Distribute per connection = 0, distribute traffic of the same protocol per client IP = 1, distribute per client IP = 2
+	Flags            LoadBalancerPortMappingFlags `json:",omitempty"`
 }
 
 // HostComputeLoadBalancer represents software load balancer.
@@ -53,6 +54,18 @@ var (
 	LoadBalancerPortMappingFlagsPreserveDIP LoadBalancerPortMappingFlags = 8
 )
 
+// LoadBalancerDistribution specifies how the loadbalancer distributes traffic.
+type LoadBalancerDistribution uint32
+
+var (
+	// LoadBalancerDistributionNone is the default and loadbalances each connection to the same pod.
+	LoadBalancerDistributionNone LoadBalancerDistribution
+	// LoadBalancerDistributionSourceIPProtocol loadbalances all traffic of the same protocol from a client IP to the same pod.
+	LoadBalancerDistributionSourceIPProtocol LoadBalancerDistribution = 1
+	// LoadBalancerDistributionSourceIP loadbalances all traffic from a client IP to the same pod.
+	LoadBalancerDistributionSourceIP LoadBalancerDistribution = 2
+)
+
 func getLoadBalancer(loadBalancerGuid guid.GUID, query string) (*HostComputeLoadBalancer, error) {
 	// Open loadBalancer.
 	var (

hcn/hcnsupport.go

@@ -13,6 +13,7 @@ type SupportedFeatures struct {
 	DSR                      bool        `json:"DSR"`
 	Slash32EndpointPrefixes  bool        `json:"Slash32EndpointPrefixes"`
 	AclSupportForProtocol252 bool        `json:"AclSupportForProtocol252"`
+	SessionAffinity          bool        `json:"SessionAffinity"`
 }
 
 // AclFeatures are the supported ACL possibilities.
@@ -57,6 +58,7 @@ func GetSupportedFeatures() SupportedFeatures {
 	features.DSR = isFeatureSupported(globals.Version, DSRVersion)
 	features.Slash32EndpointPrefixes = isFeatureSupported(globals.Version, Slash32EndpointPrefixesVersion)
 	features.AclSupportForProtocol252 = isFeatureSupported(globals.Version, AclSupportForProtocol252Version)
+	features.SessionAffinity = isFeatureSupported(globals.Version, SessionAffinityVersion)
 
 	return features
 }

hcn/hcnsupport_test.go

@@ -83,6 +83,17 @@ func TestAclSupportForProtocol252Support(t *testing.T) {
 	}
 }
 
+func TestSessionAffinitySupport(t *testing.T) {
+	supportedFeatures := GetSupportedFeatures()
+	err := SessionAffinitySupported()
+	if supportedFeatures.SessionAffinity && err != nil {
+		t.Fatal(err)
+	}
+	if !supportedFeatures.SessionAffinity && err == nil {
+		t.Fatal(err)
+	}
+}
+
 func TestIsFeatureSupported(t *testing.T) {
 	// HNSVersion1803 testing (single range tests)
 	if isFeatureSupported(Version{Major: 0, Minor: 0}, HNSVersion1803) {