feat:support slow start mode

api/v1alpha1/loadbalancer_types.go

@@ -5,10 +5,13 @@
 
 package v1alpha1
 
+import metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
 // LoadBalancer defines the load balancer policy to be applied.
 // +union
 //
 // +kubebuilder:validation:XValidation:rule="self.type == 'ConsistentHash' ? has(self.consistentHash) : !has(self.consistentHash)",message="If LoadBalancer type is consistentHash, consistentHash field needs to be set."
+// +kubebuilder:validation:XValidation:rule="self.type in ['Random', 'ConsistentHash'] ? !has(self.slowStartWindow) : true ",message="Currently SlowStartWindow is only supported for RoundRobin and LeastRequest load balancers."
 type LoadBalancer struct {
 	// Type decides the type of Load Balancer policy.
 	// Valid LoadBalancerType values are
@@ -24,6 +27,15 @@ type LoadBalancer struct {
 	//
 	// +optional
 	ConsistentHash *ConsistentHash `json:"consistentHash,omitempty"`
+
+	// SlowStartWindow defines the duration of the warm up period for newly added host.
+	// If set, during slow start window, traffic sent to the newly added hosts will gradually increase in a linear manner.
+	// Currently this is only supported for RoundRobin and LeastRequest load balancers.
+	// For additional details,
+	// see https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/cluster/v3/cluster.proto#config-cluster-v3-cluster-slowstartconfig
+	//
+	// +optional
+	SlowStartWindow *metav1.Duration `json:"slowStartWindow,omitempty"`
 }
 
 // LoadBalancerType specifies the types of LoadBalancer.

charts/gateway-helm/crds/generated/gateway.envoyproxy.io_backendtrafficpolicies.yaml

@@ -61,6 +61,14 @@ spec:
                     required:
                     - type
                     type: object
+                  slowStartWindow:
+                    description: SlowStartWindow defines the duration of the warm
+                      up period for newly added host. If set, during slow start window,
+                      traffic sent to the newly added hosts will gradually increase
+                      in a linear manner. Currently this is only supported for RoundRobin
+                      and LeastRequest load balancers. For additional details, see
+                      https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/cluster/v3/cluster.proto#config-cluster-v3-cluster-slowstartconfig
+                    type: string
                   type:
                     description: Type decides the type of Load Balancer policy. Valid
                       LoadBalancerType values are "ConsistentHash", "LeastRequest",
@@ -79,6 +87,10 @@ spec:
                     field needs to be set.
                   rule: 'self.type == ''ConsistentHash'' ? has(self.consistentHash)
                     : !has(self.consistentHash)'
+                - message: Currently SlowStartWindow is only supported for RoundRobin
+                    and LeastRequest load balancers.
+                  rule: 'self.type in [''Random'', ''ConsistentHash''] ? !has(self.slowStartWindow)
+                    : true '
               proxyProtocol:
                 description: ProxyProtocol enables the Proxy Protocol when communicating
                   with the backend.

internal/gatewayapi/backendtrafficpolicy.go

@@ -425,6 +425,9 @@ func (t *Translator) buildLoadBalancer(policy *egv1a1.BackendTrafficPolicy) *ir.
 		lb = &ir.LoadBalancer{
 			LeastRequest: &ir.LeastRequest{},
 		}
+		if policy.Spec.LoadBalancer.SlowStartWindow != nil {
+			lb.LeastRequest.SlowStartWindow = policy.Spec.LoadBalancer.SlowStartWindow.Duration
+		}
 	case egv1a1.RandomLoadBalancerType:
 		lb = &ir.LoadBalancer{
 			Random: &ir.Random{},
@@ -433,6 +436,9 @@ func (t *Translator) buildLoadBalancer(policy *egv1a1.BackendTrafficPolicy) *ir.
 		lb = &ir.LoadBalancer{
 			RoundRobin: &ir.RoundRobin{},
 		}
+		if policy.Spec.LoadBalancer.SlowStartWindow != nil {
+			lb.RoundRobin.SlowStartWindow = policy.Spec.LoadBalancer.SlowStartWindow.Duration
+		}
 	}
 
 	return lb

internal/gatewayapi/testdata/backendtrafficpolicy-with-loadbalancer.in.yaml

@@ -62,6 +62,25 @@ httpRoutes:
       backendRefs:
       - name: service-1
         port: 8080
+- apiVersion: gateway.networking.k8s.io/v1
+  kind: HTTPRoute
+  metadata:
+    namespace: default
+    name: httproute-2
+  spec:
+    hostnames:
+    - gateway.envoyproxy.io
+    parentRefs:
+    - namespace: envoy-gateway
+      name: gateway-2
+      sectionName: http
+    rules:
+    - matches:
+      - path:
+          value: "/test2"
+      backendRefs:
+      - name: service-2
+        port: 8080
 backendTrafficPolicies:
 - apiVersion: gateway.envoyproxy.io/v1alpha1
   kind: BackendTrafficPolicy
@@ -91,3 +110,31 @@ backendTrafficPolicies:
       type: ConsistentHash
       consistentHash:
         type: SourceIP
+- apiVersion: gateway.envoyproxy.io/v1alpha1
+  kind: BackendTrafficPolicy
+  metadata:
+    namespace: envoy-gateway
+    name: policy-for-gateway2
+  spec:
+    targetRef:
+      group: gateway.networking.k8s.io
+      kind: Gateway
+      name: gateway-2
+      namespace: envoy-gateway
+    loadBalancer:
+      type: RoundRobin
+      slowStartWindow: 300s
+- apiVersion: gateway.envoyproxy.io/v1alpha1
+  kind: BackendTrafficPolicy
+  metadata:
+    namespace: default
+    name: policy-for-route2
+  spec:
+    targetRef:
+      group: gateway.networking.k8s.io
+      kind: HTTPRoute
+      name: httproute-2
+      namespace: default
+    loadBalancer:
+      type: LeastRequest
+      slowStartWindow: 300s

internal/gatewayapi/testdata/backendtrafficpolicy-with-loadbalancer.out.yaml

@@ -22,6 +22,28 @@ backendTrafficPolicies:
       reason: Accepted
       status: "True"
       type: Accepted
+- apiVersion: gateway.envoyproxy.io/v1alpha1
+  kind: BackendTrafficPolicy
+  metadata:
+    creationTimestamp: null
+    name: policy-for-route2
+    namespace: default
+  spec:
+    loadBalancer:
+      slowStartWindow: 5m0s
+      type: LeastRequest
+    targetRef:
+      group: gateway.networking.k8s.io
+      kind: HTTPRoute
+      name: httproute-2
+      namespace: default
+  status:
+    conditions:
+    - lastTransitionTime: null
+      message: BackendTrafficPolicy has been accepted.
+      reason: Accepted
+      status: "True"
+      type: Accepted
 - apiVersion: gateway.envoyproxy.io/v1alpha1
   kind: BackendTrafficPolicy
   metadata:
@@ -43,6 +65,28 @@ backendTrafficPolicies:
       reason: Accepted
       status: "True"
       type: Accepted
+- apiVersion: gateway.envoyproxy.io/v1alpha1
+  kind: BackendTrafficPolicy
+  metadata:
+    creationTimestamp: null
+    name: policy-for-gateway2
+    namespace: envoy-gateway
+  spec:
+    loadBalancer:
+      slowStartWindow: 5m0s
+      type: RoundRobin
+    targetRef:
+      group: gateway.networking.k8s.io
+      kind: Gateway
+      name: gateway-2
+      namespace: envoy-gateway
+  status:
+    conditions:
+    - lastTransitionTime: null
+      message: BackendTrafficPolicy has been accepted.
+      reason: Accepted
+      status: "True"
+      type: Accepted
 gateways:
 - apiVersion: gateway.networking.k8s.io/v1
   kind: Gateway
@@ -101,7 +145,7 @@ gateways:
       protocol: HTTP
   status:
     listeners:
-    - attachedRoutes: 1
+    - attachedRoutes: 2
       conditions:
       - lastTransitionTime: null
         message: Sending translated listener configuration to the data plane
@@ -197,6 +241,44 @@ httpRoutes:
         name: gateway-2
         namespace: envoy-gateway
         sectionName: http
+- apiVersion: gateway.networking.k8s.io/v1
+  kind: HTTPRoute
+  metadata:
+    creationTimestamp: null
+    name: httproute-2
+    namespace: default
+  spec:
+    hostnames:
+    - gateway.envoyproxy.io
+    parentRefs:
+    - name: gateway-2
+      namespace: envoy-gateway
+      sectionName: http
+    rules:
+    - backendRefs:
+      - name: service-2
+        port: 8080
+      matches:
+      - path:
+          value: /test2
+  status:
+    parents:
+    - conditions:
+      - lastTransitionTime: null
+        message: Route is accepted
+        reason: Accepted
+        status: "True"
+        type: Accepted
+      - lastTransitionTime: null
+        message: Resolved all the Object references for the Route
+        reason: ResolvedRefs
+        status: "True"
+        type: ResolvedRefs
+      controllerName: gateway.envoyproxy.io/gatewayclass-controller
+      parentRef:
+        name: gateway-2
+        namespace: envoy-gateway
+        sectionName: http
 infraIR:
   envoy-gateway/gateway-1:
     proxy:
@@ -266,6 +348,26 @@ xdsIR:
       name: envoy-gateway/gateway-2/http
       port: 10080
       routes:
+      - backendWeights:
+          invalid: 0
+          valid: 0
+        destination:
+          name: httproute/default/httproute-2/rule/0
+          settings:
+          - endpoints:
+            - host: 7.7.7.7
+              port: 8080
+            protocol: HTTP
+            weight: 1
+        hostname: gateway.envoyproxy.io
+        loadBalancer:
+          leastRequest:
+            slowStartWindow: 300000000000
+        name: httproute/default/httproute-2/rule/0/match/0/gateway_envoyproxy_io
+        pathMatch:
+          distinct: false
+          name: ""
+          prefix: /test2
       - backendWeights:
           invalid: 0
           valid: 0

internal/ir/xds.go

@@ -10,6 +10,7 @@ import (
 	"errors"
 	"net"
 	"reflect"
+	"time"
 
 	"github.com/tetratelabs/multierror"
 	"golang.org/x/exp/slices"
@@ -1044,11 +1045,19 @@ func (l *LoadBalancer) Validate() error {
 
 // RoundRobin load balancer settings
 // +k8s:deepcopy-gen=true
-type RoundRobin struct{}
+type RoundRobin struct {
+	// SlowStartWindow defines the duration of the warm up period for newly added host.
+	// If set, slow start mode is enabled for newly added hosts in the cluster.
+	SlowStartWindow time.Duration `json:"slowStartWindow,omitempty" yaml:"slowStartWindow,omitempty"`
+}
 
 // LeastRequest load balancer settings
 // +k8s:deepcopy-gen=true
-type LeastRequest struct{}
+type LeastRequest struct {
+	// SlowStartWindow defines the duration of the warm up period for newly added host.
+	// If set, slow start mode is enabled for newly added hosts in the cluster.
+	SlowStartWindow time.Duration `json:"slowStartWindow,omitempty" yaml:"slowStartWindow,omitempty"`
+}
 
 // Random load balancer settings
 // +k8s:deepcopy-gen=true

internal/xds/translator/cluster.go

@@ -78,8 +78,26 @@ func buildXdsCluster(args *xdsClusterArgs) *clusterv3.Cluster {
 		cluster.LbPolicy = clusterv3.Cluster_LEAST_REQUEST
 	} else if args.loadBalancer.LeastRequest != nil {
 		cluster.LbPolicy = clusterv3.Cluster_LEAST_REQUEST
+		if args.loadBalancer.LeastRequest.SlowStartWindow > 0 {
+			cluster.LbConfig = &clusterv3.Cluster_LeastRequestLbConfig_{
+				LeastRequestLbConfig: &clusterv3.Cluster_LeastRequestLbConfig{
+					SlowStartConfig: &clusterv3.Cluster_SlowStartConfig{
+						SlowStartWindow: durationpb.New(args.loadBalancer.LeastRequest.SlowStartWindow),
+					},
+				},
+			}
+		}
 	} else if args.loadBalancer.RoundRobin != nil {
 		cluster.LbPolicy = clusterv3.Cluster_ROUND_ROBIN
+		if args.loadBalancer.RoundRobin.SlowStartWindow > 0 {
+			cluster.LbConfig = &clusterv3.Cluster_RoundRobinLbConfig_{
+				RoundRobinLbConfig: &clusterv3.Cluster_RoundRobinLbConfig{
+					SlowStartConfig: &clusterv3.Cluster_SlowStartConfig{
+						SlowStartWindow: durationpb.New(args.loadBalancer.RoundRobin.SlowStartWindow),
+					},
+				},
+			}
+		}
 	} else if args.loadBalancer.Random != nil {
 		cluster.LbPolicy = clusterv3.Cluster_RANDOM
 	} else if args.loadBalancer.ConsistentHash != nil {

internal/xds/translator/testdata/in/xds-ir/load-balancer.yaml

@@ -46,3 +46,25 @@ http:
       - endpoints:
         - host: "1.2.3.4"
           port: 50000
+  - name: "fifth-route"
+    hostname: "*"
+    loadBalancer:
+      leastRequest:
+        slowStartWindow: 100000000
+    destination:
+      name: "fifth-route-dest"
+      settings:
+      - endpoints:
+        - host: "1.2.3.4"
+          port: 50000
+  - name: "sixth-route"
+    hostname: "*"
+    loadBalancer:
+      roundRobin:
+        slowStartWindow: 600000000
+    destination:
+      name: "sixth-route-dest"
+      settings:
+      - endpoints:
+        - host: "1.2.3.4"
+          port: 50000