Introduce an upstream-hash-by annotation to support consistent hashing by nginx variable or text

pkg/ingress/annotations/upstreamhashby/main.go

@@ -0,0 +1,42 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package upstreamhashby
+
+import (
+	extensions "k8s.io/api/extensions/v1beta1"
+
+	"k8s.io/ingress-nginx/pkg/ingress/annotations/parser"
+)
+
+const (
+	annotation = "ingress.kubernetes.io/upstream-hash-by"
+)
+
+type upstreamhashby struct {
+}
+
+// NewParser creates a new CORS annotation parser
+func NewParser() parser.IngressAnnotation {
+	return upstreamhashby{}
+}
+
+// Parse parses the annotations contained in the ingress rule
+// used to indicate if the location/s contains a fragment of
+// configuration to be included inside the paths of the rules
+func (a upstreamhashby) Parse(ing *extensions.Ingress) (interface{}, error) {
+	return parser.GetStringAnnotation(annotation, ing)
+}

pkg/ingress/annotations/upstreamhashby/main_test.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package upstreamhashby
+
+import (
+	"testing"
+
+	api "k8s.io/api/core/v1"
+	extensions "k8s.io/api/extensions/v1beta1"
+	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestParse(t *testing.T) {
+	ap := NewParser()
+	if ap == nil {
+		t.Fatalf("expected a parser.IngressAnnotation but returned nil")
+	}
+
+	testCases := []struct {
+		annotations map[string]string
+		expected    string
+	}{
+		{map[string]string{annotation: "$request_uri"}, "$request_uri"},
+		{map[string]string{annotation: "false"}, "false"},
+		{map[string]string{}, ""},
+		{nil, ""},
+	}
+
+	ing := &extensions.Ingress{
+		ObjectMeta: meta_v1.ObjectMeta{
+			Name:      "foo",
+			Namespace: api.NamespaceDefault,
+		},
+		Spec: extensions.IngressSpec{},
+	}
+
+	for _, testCase := range testCases {
+		ing.SetAnnotations(testCase.annotations)
+		result, _ := ap.Parse(ing)
+		if result != testCase.expected {
+			t.Errorf("expected %v but returned %v, annotations: %s", testCase.expected, result, testCase.annotations)
+		}
+	}
+}

pkg/ingress/controller/annotations.go

@@ -41,6 +41,7 @@ import (
 	"k8s.io/ingress-nginx/pkg/ingress/annotations/sessionaffinity"
 	"k8s.io/ingress-nginx/pkg/ingress/annotations/snippet"
 	"k8s.io/ingress-nginx/pkg/ingress/annotations/sslpassthrough"
+	"k8s.io/ingress-nginx/pkg/ingress/annotations/upstreamhashby"
 	"k8s.io/ingress-nginx/pkg/ingress/annotations/upstreamvhost"
 	"k8s.io/ingress-nginx/pkg/ingress/annotations/vtsfilterkey"
 	"k8s.io/ingress-nginx/pkg/ingress/errors"
@@ -82,6 +83,7 @@ func newAnnotationExtractor(cfg extractorConfig) annotationExtractor {
 			"Alias":                alias.NewParser(),
 			"ClientBodyBufferSize": clientbodybuffersize.NewParser(),
 			"DefaultBackend":       defaultbackend.NewParser(cfg),
+			"UpstreamHashBy":       upstreamhashby.NewParser(),
 			"UpstreamVhost":        upstreamvhost.NewParser(),
 			"VtsFilterKey":         vtsfilterkey.NewParser(),
 			"ServerSnippet":        serversnippet.NewParser(),
@@ -131,6 +133,7 @@ const (
 	clientBodyBufferSize = "ClientBodyBufferSize"
 	certificateAuth      = "CertificateAuth"
 	serverSnippet        = "ServerSnippet"
+	upstreamHashBy       = "UpstreamHashBy"
 )
 
 func (e *annotationExtractor) ServiceUpstream(ing *extensions.Ingress) bool {
@@ -189,3 +192,8 @@ func (e *annotationExtractor) ServerSnippet(ing *extensions.Ingress) string {
 	val, _ := e.annotations[serverSnippet].Parse(ing)
 	return val.(string)
 }
+
+func (e *annotationExtractor) UpstreamHashBy(ing *extensions.Ingress) string {
+	val, _ := e.annotations[upstreamHashBy].Parse(ing)
+	return val.(string)
+}

pkg/ingress/controller/annotations_test.go

@@ -37,6 +37,7 @@ const (
 	annotationAffinityType       = "ingress.kubernetes.io/affinity"
 	annotationAffinityCookieName = "ingress.kubernetes.io/session-cookie-name"
 	annotationAffinityCookieHash = "ingress.kubernetes.io/session-cookie-hash"
+	annotationUpstreamHashBy     = "ingress.kubernetes.io/upstream-hash-by"
 )
 
 type mockCfg struct {
@@ -233,6 +234,30 @@ func TestSSLPassthrough(t *testing.T) {
 	}
 }
 
+func TestUpstreamHashBy(t *testing.T) {
+	ec := newAnnotationExtractor(mockCfg{})
+	ing := buildIngress()
+
+	fooAnns := []struct {
+		annotations map[string]string
+		er          string
+	}{
+		{map[string]string{annotationUpstreamHashBy: "$request_uri"}, "$request_uri"},
+		{map[string]string{annotationUpstreamHashBy: "false"}, "false"},
+		{map[string]string{annotationUpstreamHashBy + "_no": "true"}, ""},
+		{map[string]string{}, ""},
+		{nil, ""},
+	}
+
+	for _, foo := range fooAnns {
+		ing.SetAnnotations(foo.annotations)
+		r := ec.UpstreamHashBy(ing)
+		if r != foo.er {
+			t.Errorf("Returned %v but expected %v", r, foo.er)
+		}
+	}
+}
+
 func TestAffinitySession(t *testing.T) {
 	ec := newAnnotationExtractor(mockCfg{})
 	ing := buildIngress()

pkg/ingress/controller/controller.go

@@ -707,6 +707,7 @@ func (ic *GenericController) createUpstreams(data []*extensions.Ingress, du *ing
 		secUpstream := ic.annotations.SecureUpstream(ing)
 		hz := ic.annotations.HealthCheck(ing)
 		serviceUpstream := ic.annotations.ServiceUpstream(ing)
+		upstreamHashBy := ic.annotations.UpstreamHashBy(ing)
 
 		var defBackend string
 		if ing.Spec.Backend != nil {
@@ -767,6 +768,10 @@ func (ic *GenericController) createUpstreams(data []*extensions.Ingress, du *ing
 					upstreams[name].SecureCACert = secUpstream.CACert
 				}
 
+				if upstreams[name].UpstreamHashBy == "" {
+					upstreams[name].UpstreamHashBy = upstreamHashBy
+				}
+
 				svcKey := fmt.Sprintf("%v/%v", ing.GetNamespace(), path.Backend.ServiceName)
 
 				// Add the service cluster endpoint as the upstream instead of individual endpoints

pkg/ingress/defaults/main.go

@@ -92,6 +92,12 @@ type Backend struct {
 	// Default: 0, ie use platform liveness probe
 	UpstreamFailTimeout int `json:"upstream-fail-timeout"`
 
+	// Enable stickiness by client-server mapping based on a NGINX variable, text or a combination of both.
+	// A consistent hashing method will be used which ensures only a few keys would be remapped to different
+	// servers on upstream group changes
+	// http://nginx.org/en/docs/http/ngx_http_upstream_module.html#hash
+	UpstreamHashBy string `json:"upstream-hash-by"`
+
 	// WhitelistSourceRange allows limiting access to certain client addresses
 	// http://nginx.org/en/docs/http/ngx_http_access_module.html
 	WhitelistSourceRange []string `json:"whitelist-source-range,-"`

pkg/ingress/types.go

@@ -170,6 +170,8 @@ type Backend struct {
 	Endpoints []Endpoint `json:"endpoints,omitempty"`
 	// StickySessionAffinitySession contains the StickyConfig object with stickness configuration
 	SessionAffinity SessionAffinityConfig `json:"sessionAffinityConfig"`
+	// Consistent hashing by NGINX variable
+	UpstreamHashBy string `json:"upstream-hash-by,omitempty"`
 }
 
 // SessionAffinityConfig describes different affinity configurations for new sessions.

pkg/ingress/types_equals.go

@@ -173,6 +173,9 @@ func (b1 *Backend) Equal(b2 *Backend) bool {
 	if !(&b1.SessionAffinity).Equal(&b2.SessionAffinity) {
 		return false
 	}
+	if b1.UpstreamHashBy != b2.UpstreamHashBy {
+		return false
+	}
 
 	if len(b1.Endpoints) != len(b2.Endpoints) {
 		return false