Add a mechanism to format the sticky cookie value

Co-authored-by: Jean-Baptiste Doumenjou <925513+jbdoumenjou@users.noreply.github.com>

docs/content/routing/services/index.md

@@ -167,8 +167,8 @@ For now, only round robin load balancing is supported:
 
 #### Sticky sessions
 
-When sticky sessions are enabled, a cookie is set on the initial request and response to let the client know which server handles the first response.
+When sticky sessions are enabled, a `Set-Cookie` header is set on the initial response to let the client know which server handles the first response.
-On subsequent requests, to keep the session alive with the same server, the client should resend the same cookie.
+On subsequent requests, to keep the session alive with the same server, the client should send the cookie with the value set.
 
 !!! info "Stickiness on multiple levels"
 

go.mod

@@ -77,7 +77,7 @@ require (
 	github.com/unrolled/render v1.0.2
 	github.com/unrolled/secure v1.0.7
 	github.com/vdemeester/shakers v0.1.0
-	github.com/vulcand/oxy v1.2.0
+	github.com/vulcand/oxy v1.3.0
 	github.com/vulcand/predicate v1.1.0
 	go.elastic.co/apm v1.7.0
 	go.elastic.co/apm/module/apmot v1.7.0

go.sum

@@ -912,6 +912,8 @@ github.com/santhosh-tekuri/jsonschema v1.2.4 h1:hNhW8e7t+H1vgY+1QeEQpveR6D4+OwKP
 github.com/santhosh-tekuri/jsonschema v1.2.4/go.mod h1:TEAUOeZSmIxTTuHatJzrvARHiuO9LYd+cIxzgEHCQI4=
 github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529 h1:nn5Wsu0esKSJiIVhscUtVbo7ada43DJhG55ua/hjS5I=
 github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529/go.mod h1:DxrIzT+xaE7yg65j358z/aeFdxmN0P9QXhEzd20vsDc=
+github.com/segmentio/fasthash v1.0.3 h1:EI9+KE1EwvMLBWwjpRDc+fEM+prwxDYbslddQGtrmhM=
+github.com/segmentio/fasthash v1.0.3/go.mod h1:waKX8l2N8yckOgmSsXJi7x1ZfdKZ4x7KRMzBtS3oedY=
 github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
 github.com/shopspring/decimal v1.2.0 h1:abSATXmQEYyShuxI4/vyW3tV1MrKAJzCZ/0zLUXYbsQ=
 github.com/shopspring/decimal v1.2.0/go.mod h1:DKyhrW/HYNuLGql+MJL6WCR6knT2jwCFRcu2hWCYk4o=
@@ -1039,8 +1041,8 @@ github.com/vdemeester/shakers v0.1.0/go.mod h1:IZ1HHynUOQt32iQ3rvAeVddXLd19h/6LW
 github.com/vektah/gqlparser v1.1.2/go.mod h1:1ycwN7Ij5njmMkPPAOaRFY4rET2Enx7IkVv3vaXspKw=
 github.com/viant/assertly v0.4.8/go.mod h1:aGifi++jvCrUaklKEKT0BU95igDNaqkvz+49uaYMPRU=
 github.com/viant/toolbox v0.24.0/go.mod h1:OxMCG57V0PXuIP2HNQrtJf2CjqdmbrOx5EkMILuUhzM=
-github.com/vulcand/oxy v1.2.0 h1:Y2Wt1EgQddA/qMnp1+YXjehPsyw2Gy8CAfavkFF+fQk=
+github.com/vulcand/oxy v1.3.0 h1:358BVHmJNLjhOrhbjq2EVJX5NQ3HxrP0d5OyHLRliX0=
-github.com/vulcand/oxy v1.2.0/go.mod h1:nGeNTWfyYQj3ghi3W8ok7vLSkw7Gkvr0x+G/v8Wk7vM=
+github.com/vulcand/oxy v1.3.0/go.mod h1:hN/gw/jg+GH4A+bqvznsW26Izd4jNGV6h1z3s7drRzs=
 github.com/vulcand/predicate v1.1.0 h1:Gq/uWopa4rx/tnZu2opOSBqHK63Yqlou/SzrbwdJiNg=
 github.com/vulcand/predicate v1.1.0/go.mod h1:mlccC5IRBoc2cIFmCB8ZM62I3VDb6p2GXESMHa3CnZg=
 github.com/vultr/govultr/v2 v2.4.0 h1:6ySGGAsoOann0lmVNkS8grLvbAT2iYWnO4R1RVYFg0A=

pkg/server/service/service.go

@@ -26,6 +26,7 @@ import (
 	"github.com/traefik/traefik/v2/pkg/server/service/loadbalancer/mirror"
 	"github.com/traefik/traefik/v2/pkg/server/service/loadbalancer/wrr"
 	"github.com/vulcand/oxy/roundrobin"
+	"github.com/vulcand/oxy/roundrobin/stickycookie"
 )
 
 const (
@@ -310,7 +311,13 @@ func (m *Manager) getLoadBalancer(ctx context.Context, serviceName string, servi
 			SameSite: convertSameSite(service.Sticky.Cookie.SameSite),
 		}
 
-		options = append(options, roundrobin.EnableStickySession(roundrobin.NewStickySessionWithOptions(cookieName, opts)))
+		// Sticky Cookie Value
+		cv, err := stickycookie.NewFallbackValue(&stickycookie.RawValue{}, &stickycookie.HashValue{})
+		if err != nil {
+			return nil, err
+		}
+
+		options = append(options, roundrobin.EnableStickySession(roundrobin.NewStickySessionWithOptions(cookieName, opts).SetCookieValue(cv)))
 
 		logger.Debugf("Sticky session cookie name: %v", cookieName)
 	}

pkg/server/service/service_test.go

@@ -120,6 +120,7 @@ func TestGetLoadBalancerServiceHandler(t *testing.T) {
 		serviceName      string
 		service          *dynamic.ServersLoadBalancer
 		responseModifier func(*http.Response) error
+		cookieRawValue   string
 
 		expected []ExpectedResult
 	}{
@@ -258,6 +259,34 @@ func TestGetLoadBalancerServiceHandler(t *testing.T) {
 				},
 			},
 		},
+		{
+			desc:        "Cookie value is backward compatible",
+			serviceName: "test",
+			service: &dynamic.ServersLoadBalancer{
+				Sticky: &dynamic.Sticky{
+					Cookie: &dynamic.Cookie{},
+				},
+				Servers: []dynamic.Server{
+					{
+						URL: server1.URL,
+					},
+					{
+						URL: server2.URL,
+					},
+				},
+			},
+			cookieRawValue: "_6f743=" + server1.URL,
+			expected: []ExpectedResult{
+				{
+					StatusCode: http.StatusOK,
+					XFrom:      "first",
+				},
+				{
+					StatusCode: http.StatusOK,
+					XFrom:      "first",
+				},
+			},
+		},
 	}
 
 	for _, test := range testCases {
@@ -269,6 +298,10 @@ func TestGetLoadBalancerServiceHandler(t *testing.T) {
 			assert.NotNil(t, handler)
 
 			req := testhelpers.MustNewRequest(http.MethodGet, "http://callme", nil)
+			if test.cookieRawValue != "" {
+				req.Header.Set("Cookie", test.cookieRawValue)
+			}
+
 			for _, expected := range test.expected {
 				recorder := httptest.NewRecorder()
 
@@ -282,6 +315,7 @@ func TestGetLoadBalancerServiceHandler(t *testing.T) {
 					req.Header.Set("Cookie", cookieHeader)
 					assert.Equal(t, expected.SecureCookie, strings.Contains(cookieHeader, "Secure"))
 					assert.Equal(t, expected.HTTPOnlyCookie, strings.Contains(cookieHeader, "HttpOnly"))
+					assert.NotContains(t, cookieHeader, "://")
 				}
 			}
 		})