Add session persistence support for NGINX Plus users using the sticky cookie directive (#4305)

Problem: Users want to be able to specify session persistence for their upstreams.

Solution: Add support for session persistence using sticky cookie directives which is only available for NGINX Plus users.

Author: salonichf5

internal/controller/manager.go

@@ -140,10 +140,13 @@ func StartManager(cfg config.Config) error {
 			GenericValidator:    genericValidator,
 			PolicyValidator:     policyManager,
 		},
-		EventRecorder:        recorder,
-		MustExtractGVK:       mustExtractGVK,
-		PlusSecrets:          plusSecrets,
-		ExperimentalFeatures: cfg.ExperimentalFeatures,
+		EventRecorder:  recorder,
+		MustExtractGVK: mustExtractGVK,
+		PlusSecrets:    plusSecrets,
+		FeatureFlags: graph.FeatureFlags{
+			Plus:         cfg.Plus,
+			Experimental: cfg.ExperimentalFeatures,
+		},
 	})
 
 	var handlerCollector handlerMetricsCollector = collectors.NewControllerNoopCollector()

internal/controller/nginx/config/http/config.go

@@ -120,6 +120,7 @@ const (
 
 // Upstream holds all configuration for an HTTP upstream.
 type Upstream struct {
+	SessionPersistence  UpstreamSessionPersistence
 	Name                string
 	ZoneSize            string // format: 512k, 1m
 	StateFile           string
@@ -129,6 +130,14 @@ type Upstream struct {
 	Servers             []UpstreamServer
 }
 
+// UpstreamSessionPersistence holds the session persistence configuration for an upstream.
+type UpstreamSessionPersistence struct {
+	Name        string
+	Expiry      string
+	Path        string
+	SessionType string
+}
+
 // UpstreamKeepAlive holds the keepalive configuration for an HTTP upstream.
 type UpstreamKeepAlive struct {
 	Time        string

internal/controller/nginx/config/upstreams.go

@@ -147,6 +147,7 @@ func (g GeneratorImpl) createUpstream(
 	processor upstreamsettings.Processor,
 ) http.Upstream {
 	var stateFile string
+	var sp http.UpstreamSessionPersistence
 	upstreamPolicySettings := processor.Process(up.Policies)
 
 	zoneSize := ossZoneSize
@@ -155,8 +156,14 @@ func (g GeneratorImpl) createUpstream(
 		// Only set state file if the upstream doesn't have resolve servers
 		// Upstreams with resolve servers can't be managed via NGINX Plus API
 		if !upstreamHasResolveServers(up) {
-			stateFile = fmt.Sprintf("%s/%s.conf", stateDir, up.Name)
+			base := up.StateFileKey
+			if base == "" {
+				base = up.Name
+			}
+			stateFile = fmt.Sprintf("%s/%s.conf", stateDir, base)
 		}
+
+		sp = getSessionPersistenceConfiguration(up.SessionPersistence)
 	}
 
 	if upstreamPolicySettings.ZoneSize != "" {
@@ -212,6 +219,7 @@ func (g GeneratorImpl) createUpstream(
 		Servers:             upstreamServers,
 		KeepAlive:           upstreamPolicySettings.KeepAlive,
 		LoadBalancingMethod: chosenLBMethod,
+		SessionPersistence:  sp,
 	}
 }
 
@@ -236,3 +244,17 @@ func upstreamHasResolveServers(upstream dataplane.Upstream) bool {
 	}
 	return false
 }
+
+// getSessionPersistenceConfiguration gets the session persistence configuration for an upstream.
+// Supported only for NGINX Plus and cookie-based type.
+func getSessionPersistenceConfiguration(sp dataplane.SessionPersistenceConfig) http.UpstreamSessionPersistence {
+	if sp.Name == "" {
+		return http.UpstreamSessionPersistence{}
+	}
+	return http.UpstreamSessionPersistence{
+		Name:        sp.Name,
+		Expiry:      sp.Expiry,
+		Path:        sp.Path,
+		SessionType: string(sp.SessionType),
+	}
+}

internal/controller/nginx/config/upstreams_template.go

@@ -17,6 +17,12 @@ upstream {{ $u.Name }} {
     zone {{ $u.Name }} {{ $u.ZoneSize }};
     {{ end -}}
 
+    {{ if $u.SessionPersistence.Name -}}
+    sticky {{ $u.SessionPersistence.SessionType }} {{ $u.SessionPersistence.Name }}
+    {{- if $u.SessionPersistence.Expiry }} expires={{ $u.SessionPersistence.Expiry }}{{- end }}
+    {{- if $u.SessionPersistence.Path }} path={{ $u.SessionPersistence.Path }}{{- end }};
+    {{ end -}}
+
     {{- if $u.StateFile }}
     state {{ $u.StateFile }};
     {{- else }}