Merge branch v2.8 into v2.9

docs/content/providers/ecs.md

@@ -169,6 +169,70 @@ providers:
 # ...
 ```
 
+### `constraints`
+
+_Optional, Default=""_
+
+The `constraints` option can be set to an expression that Traefik matches against the container labels (task),
+to determine whether to create any route for that container. 
+If none of the container labels match the expression, no route for that container is created. 
+If the expression is empty, all detected containers are included.
+
+The expression syntax is based on the `Label("key", "value")`, and `LabelRegex("key", "value")` functions,
+as well as the usual boolean logic, as shown in examples below.
+
+??? example "Constraints Expression Examples"
+
+    ```toml
+    # Includes only containers having a label with key `a.label.name` and value `foo`
+    constraints = "Label(`a.label.name`, `foo`)"
+    ```
+
+    ```toml
+    # Excludes containers having any label with key `a.label.name` and value `foo`
+    constraints = "!Label(`a.label.name`, `value`)"
+    ```
+
+    ```toml
+    # With logical AND.
+    constraints = "Label(`a.label.name`, `valueA`) && Label(`another.label.name`, `valueB`)"
+    ```
+
+    ```toml
+    # With logical OR.
+    constraints = "Label(`a.label.name`, `valueA`) || Label(`another.label.name`, `valueB`)"
+    ```
+
+    ```toml
+    # With logical AND and OR, with precedence set by parentheses.
+    constraints = "Label(`a.label.name`, `valueA`) && (Label(`another.label.name`, `valueB`) || Label(`yet.another.label.name`, `valueC`))"
+    ```
+
+    ```toml
+    # Includes only containers having a label with key `a.label.name` and a value matching the `a.+` regular expression.
+    constraints = "LabelRegex(`a.label.name`, `a.+`)"
+    ```
+
+For additional information, refer to [Restrict the Scope of Service Discovery](./overview.md#restrict-the-scope-of-service-discovery).
+
+```yaml tab="File (YAML)"
+providers:
+  ecs:
+    constraints: "Label(`a.label.name`,`foo`)"
+    # ...
+```
+
+```toml tab="File (TOML)"
+[providers.ecs]
+  constraints = "Label(`a.label.name`,`foo`)"
+  # ...
+```
+
+```bash tab="CLI"
+--providers.ecs.constraints=Label(`a.label.name`,`foo`)
+# ...
+```
+
 ### `defaultRule`
 
 _Optional, Default=```Host(`{{ normalize .Name }}`)```_

docs/content/providers/overview.md

@@ -213,6 +213,7 @@ you can do so in two different ways:
 List of providers that support these features:
 
 - [Docker](./docker.md#exposedbydefault)
+- [ECS](./ecs.md#exposedbydefault)
 - [Consul Catalog](./consul-catalog.md#exposedbydefault)
 - [Nomad](./nomad.md#exposedbydefault)
 - [Rancher](./rancher.md#exposedbydefault)
@@ -223,6 +224,7 @@ List of providers that support these features:
 List of providers that support constraints:
 
 - [Docker](./docker.md#constraints)
+- [ECS](./ecs.md#constraints)
 - [Consul Catalog](./consul-catalog.md#constraints)
 - [Nomad](./nomad.md#constraints)
 - [Rancher](./rancher.md#constraints)

pkg/provider/consulcatalog/config.go

@@ -195,29 +195,27 @@ func (p *Provider) addServerTCP(item itemData, loadBalancer *dynamic.TCPServersL
 		return errors.New("load-balancer is not defined")
 	}
 
-	var port string
-	if len(loadBalancer.Servers) > 0 {
-		port = loadBalancer.Servers[0].Port
-	}
-
 	if len(loadBalancer.Servers) == 0 {
 		loadBalancer.Servers = []dynamic.TCPServer{{}}
 	}
 
-	if item.Port != "" && port == "" {
-		port = item.Port
-	}
-	loadBalancer.Servers[0].Port = ""
-
-	if port == "" {
-		return errors.New("port is missing")
-	}
-
 	if item.Address == "" {
 		return errors.New("address is missing")
 	}
 
+	port := loadBalancer.Servers[0].Port
+	loadBalancer.Servers[0].Port = ""
+
+	if port == "" {
+		port = item.Port
+	}
+
+	if port == "" {
+		return errors.New("port is missing")
+	}
+
 	loadBalancer.Servers[0].Address = net.JoinHostPort(item.Address, port)
+
 	return nil
 }
 
@@ -230,21 +228,23 @@ func (p *Provider) addServerUDP(item itemData, loadBalancer *dynamic.UDPServersL
 		loadBalancer.Servers = []dynamic.UDPServer{{}}
 	}
 
-	var port string
+	if item.Address == "" {
-	if item.Port != "" {
+		return errors.New("address is missing")
+	}
+
+	port := loadBalancer.Servers[0].Port
+	loadBalancer.Servers[0].Port = ""
+
+	if port == "" {
 		port = item.Port
-		loadBalancer.Servers[0].Port = ""
 	}
 
 	if port == "" {
 		return errors.New("port is missing")
 	}
 
-	if item.Address == "" {
-		return errors.New("address is missing")
-	}
-
 	loadBalancer.Servers[0].Address = net.JoinHostPort(item.Address, port)
+
 	return nil
 }
 
@@ -253,11 +253,6 @@ func (p *Provider) addServer(item itemData, loadBalancer *dynamic.ServersLoadBal
 		return errors.New("load-balancer is not defined")
 	}
 
-	var port string
-	if len(loadBalancer.Servers) > 0 {
-		port = loadBalancer.Servers[0].Port
-	}
-
 	if len(loadBalancer.Servers) == 0 {
 		server := dynamic.Server{}
 		server.SetDefaults()
@@ -265,17 +260,19 @@ func (p *Provider) addServer(item itemData, loadBalancer *dynamic.ServersLoadBal
 		loadBalancer.Servers = []dynamic.Server{server}
 	}
 
-	if item.Port != "" && port == "" {
+	if item.Address == "" {
-		port = item.Port
+		return errors.New("address is missing")
 	}
+
+	port := loadBalancer.Servers[0].Port
 	loadBalancer.Servers[0].Port = ""
 
 	if port == "" {
-		return errors.New("port is missing")
+		port = item.Port
 	}
 
-	if item.Address == "" {
+	if port == "" {
-		return errors.New("address is missing")
+		return errors.New("port is missing")
 	}
 
 	scheme := loadBalancer.Servers[0].Scheme

pkg/provider/consulcatalog/config_test.go

@@ -2220,7 +2220,7 @@ func Test_buildConfiguration(t *testing.T) {
 					Labels: map[string]string{
 						"traefik.tcp.routers.foo.rule":                      "HostSNI(`foo.bar`)",
 						"traefik.tcp.routers.foo.tls.options":               "foo",
-						"traefik.tcp.services.foo.loadbalancer.server.port": "80",
+						"traefik.tcp.services.foo.loadbalancer.server.port": "8080",
 					},
 					Address: "127.0.0.1",
 					Port:    "80",
@@ -2244,7 +2244,7 @@ func Test_buildConfiguration(t *testing.T) {
 							LoadBalancer: &dynamic.TCPServersLoadBalancer{
 								Servers: []dynamic.TCPServer{
 									{
-										Address: "127.0.0.1:80",
+										Address: "127.0.0.1:8080",
 									},
 								},
 								TerminationDelay: Int(100),
@@ -2858,6 +2858,57 @@ func Test_buildConfiguration(t *testing.T) {
 				},
 			},
 		},
+		{
+			desc:         "UDP service with labels only",
+			ConnectAware: true,
+			items: []itemData{
+				{
+					ID:         "1",
+					Node:       "Node1",
+					Datacenter: "dc1",
+					Name:       "Test",
+					Namespace:  "ns",
+					Labels: map[string]string{
+						"traefik.udp.routers.test-udp-label.service":                           "test-udp-label-service",
+						"traefik.udp.routers.test-udp-label.entryPoints":                       "udp",
+						"traefik.udp.services.test-udp-label-service.loadBalancer.server.port": "21116",
+					},
+					Address: "127.0.0.1",
+					Port:    "80",
+					Status:  api.HealthPassing,
+				},
+			},
+			expected: &dynamic.Configuration{
+				TCP: &dynamic.TCPConfiguration{
+					Routers:     map[string]*dynamic.TCPRouter{},
+					Middlewares: map[string]*dynamic.TCPMiddleware{},
+					Services:    map[string]*dynamic.TCPService{},
+				},
+				UDP: &dynamic.UDPConfiguration{
+					Routers: map[string]*dynamic.UDPRouter{
+						"test-udp-label": {
+							EntryPoints: []string{"udp"},
+							Service:     "test-udp-label-service",
+						},
+					},
+					Services: map[string]*dynamic.UDPService{
+						"test-udp-label-service": {
+							LoadBalancer: &dynamic.UDPServersLoadBalancer{
+								Servers: []dynamic.UDPServer{
+									{Address: "127.0.0.1:21116"},
+								},
+							},
+						},
+					},
+				},
+				HTTP: &dynamic.HTTPConfiguration{
+					Routers:           map[string]*dynamic.Router{},
+					Middlewares:       map[string]*dynamic.Middleware{},
+					Services:          map[string]*dynamic.Service{},
+					ServersTransports: map[string]*dynamic.ServersTransport{},
+				},
+			},
+		},
 	}
 
 	for _, test := range testCases {

pkg/provider/docker/config.go

@@ -196,28 +196,24 @@ func (p *Provider) addServerTCP(ctx context.Context, container dockerData, loadB
 		return errors.New("load-balancer is not defined")
 	}
 
-	var serverPort string
+	if len(loadBalancer.Servers) == 0 {
-	if len(loadBalancer.Servers) > 0 {
+		loadBalancer.Servers = []dynamic.TCPServer{{}}
-		serverPort = loadBalancer.Servers[0].Port
-		loadBalancer.Servers[0].Port = ""
 	}
 
+	serverPort := loadBalancer.Servers[0].Port
+	loadBalancer.Servers[0].Port = ""
+
 	ip, port, err := p.getIPPort(ctx, container, serverPort)
 	if err != nil {
 		return err
 	}
 
-	if len(loadBalancer.Servers) == 0 {
-		server := dynamic.TCPServer{}
-
-		loadBalancer.Servers = []dynamic.TCPServer{server}
-	}
-
 	if port == "" {
 		return errors.New("port is missing")
 	}
 
 	loadBalancer.Servers[0].Address = net.JoinHostPort(ip, port)
+
 	return nil
 }
 
@@ -226,28 +222,24 @@ func (p *Provider) addServerUDP(ctx context.Context, container dockerData, loadB
 		return errors.New("load-balancer is not defined")
 	}
 
-	var serverPort string
+	if len(loadBalancer.Servers) == 0 {
-	if len(loadBalancer.Servers) > 0 {
+		loadBalancer.Servers = []dynamic.UDPServer{{}}
-		serverPort = loadBalancer.Servers[0].Port
-		loadBalancer.Servers[0].Port = ""
 	}
 
+	serverPort := loadBalancer.Servers[0].Port
+	loadBalancer.Servers[0].Port = ""
+
 	ip, port, err := p.getIPPort(ctx, container, serverPort)
 	if err != nil {
 		return err
 	}
 
-	if len(loadBalancer.Servers) == 0 {
-		server := dynamic.UDPServer{}
-
-		loadBalancer.Servers = []dynamic.UDPServer{server}
-	}
-
 	if port == "" {
 		return errors.New("port is missing")
 	}
 
 	loadBalancer.Servers[0].Address = net.JoinHostPort(ip, port)
+
 	return nil
 }
 
@@ -256,17 +248,6 @@ func (p *Provider) addServer(ctx context.Context, container dockerData, loadBala
 		return errors.New("load-balancer is not defined")
 	}
 
-	var serverPort string
-	if len(loadBalancer.Servers) > 0 {
-		serverPort = loadBalancer.Servers[0].Port
-		loadBalancer.Servers[0].Port = ""
-	}
-
-	ip, port, err := p.getIPPort(ctx, container, serverPort)
-	if err != nil {
-		return err
-	}
-
 	if len(loadBalancer.Servers) == 0 {
 		server := dynamic.Server{}
 		server.SetDefaults()
@@ -274,6 +255,14 @@ func (p *Provider) addServer(ctx context.Context, container dockerData, loadBala
 		loadBalancer.Servers = []dynamic.Server{server}
 	}
 
+	serverPort := loadBalancer.Servers[0].Port
+	loadBalancer.Servers[0].Port = ""
+
+	ip, port, err := p.getIPPort(ctx, container, serverPort)
+	if err != nil {
+		return err
+	}
+
 	if port == "" {
 		return errors.New("port is missing")
 	}

pkg/provider/ecs/config.go

@@ -185,7 +185,7 @@ func (p *Provider) filterInstance(ctx context.Context, instance ecsInstance) boo
 
 	matches, err := constraints.MatchLabels(instance.Labels, p.Constraints)
 	if err != nil {
-		logger.Errorf("Error matching constraints expression: %v", err)
+		logger.Errorf("Error matching constraint expression: %v", err)
 		return false
 	}
 	if !matches {
@@ -201,28 +201,24 @@ func (p *Provider) addServerTCP(instance ecsInstance, loadBalancer *dynamic.TCPS
 		return errors.New("load-balancer is not defined")
 	}
 
-	var serverPort string
+	if len(loadBalancer.Servers) == 0 {
-	if len(loadBalancer.Servers) > 0 {
+		loadBalancer.Servers = []dynamic.TCPServer{{}}
-		serverPort = loadBalancer.Servers[0].Port
-		loadBalancer.Servers[0].Port = ""
 	}
 
+	serverPort := loadBalancer.Servers[0].Port
+	loadBalancer.Servers[0].Port = ""
+
 	ip, port, err := p.getIPPort(instance, serverPort)
 	if err != nil {
 		return err
 	}
 
-	if len(loadBalancer.Servers) == 0 {
-		server := dynamic.TCPServer{}
-
-		loadBalancer.Servers = []dynamic.TCPServer{server}
-	}
-
 	if port == "" {
 		return errors.New("port is missing")
 	}
 
 	loadBalancer.Servers[0].Address = net.JoinHostPort(ip, port)
+
 	return nil
 }
 
@@ -231,28 +227,24 @@ func (p *Provider) addServerUDP(instance ecsInstance, loadBalancer *dynamic.UDPS
 		return errors.New("load-balancer is not defined")
 	}
 
-	var serverPort string
+	if len(loadBalancer.Servers) == 0 {
-	if len(loadBalancer.Servers) > 0 {
+		loadBalancer.Servers = []dynamic.UDPServer{{}}
-		serverPort = loadBalancer.Servers[0].Port
-		loadBalancer.Servers[0].Port = ""
 	}
 
+	serverPort := loadBalancer.Servers[0].Port
+	loadBalancer.Servers[0].Port = ""
+
 	ip, port, err := p.getIPPort(instance, serverPort)
 	if err != nil {
 		return err
 	}
 
-	if len(loadBalancer.Servers) == 0 {
-		server := dynamic.UDPServer{}
-
-		loadBalancer.Servers = []dynamic.UDPServer{server}
-	}
-
 	if port == "" {
 		return errors.New("port is missing")
 	}
 
 	loadBalancer.Servers[0].Address = net.JoinHostPort(ip, port)
+
 	return nil
 }
 
@@ -261,17 +253,6 @@ func (p *Provider) addServer(instance ecsInstance, loadBalancer *dynamic.Servers
 		return errors.New("load-balancer is not defined")
 	}
 
-	var serverPort string
-	if len(loadBalancer.Servers) > 0 {
-		serverPort = loadBalancer.Servers[0].Port
-		loadBalancer.Servers[0].Port = ""
-	}
-
-	ip, port, err := p.getIPPort(instance, serverPort)
-	if err != nil {
-		return err
-	}
-
 	if len(loadBalancer.Servers) == 0 {
 		server := dynamic.Server{}
 		server.SetDefaults()
@@ -279,6 +260,14 @@ func (p *Provider) addServer(instance ecsInstance, loadBalancer *dynamic.Servers
 		loadBalancer.Servers = []dynamic.Server{server}
 	}
 
+	serverPort := loadBalancer.Servers[0].Port
+	loadBalancer.Servers[0].Port = ""
+
+	ip, port, err := p.getIPPort(instance, serverPort)
+	if err != nil {
+		return err
+	}
+
 	if port == "" {
 		return errors.New("port is missing")
 	}

pkg/provider/nomad/config.go

@@ -175,29 +175,27 @@ func (p *Provider) addServerTCP(i item, lb *dynamic.TCPServersLoadBalancer) erro
 		return errors.New("load-balancer is missing")
 	}
 
-	var port string
-	if len(lb.Servers) > 0 {
-		port = lb.Servers[0].Port
-	}
-
 	if len(lb.Servers) == 0 {
 		lb.Servers = []dynamic.TCPServer{{}}
 	}
 
-	if i.Port != 0 && port == "" {
-		port = strconv.Itoa(i.Port)
-	}
-	lb.Servers[0].Port = ""
-
-	if port == "" {
-		return errors.New("port is missing")
-	}
-
 	if i.Address == "" {
 		return errors.New("address is missing")
 	}
 
+	port := lb.Servers[0].Port
+	lb.Servers[0].Port = ""
+
+	if port == "" && i.Port > 0 {
+		port = strconv.Itoa(i.Port)
+	}
+
+	if port == "" {
+		return errors.New("port is missing")
+	}
+
 	lb.Servers[0].Address = net.JoinHostPort(i.Address, port)
+
 	return nil
 }
 
@@ -206,29 +204,27 @@ func (p *Provider) addServerUDP(i item, lb *dynamic.UDPServersLoadBalancer) erro
 		return errors.New("load-balancer is missing")
 	}
 
-	var port string
-	if len(lb.Servers) > 0 {
-		port = lb.Servers[0].Port
-	}
-
 	if len(lb.Servers) == 0 {
 		lb.Servers = []dynamic.UDPServer{{}}
 	}
 
-	if i.Port != 0 && port == "" {
-		port = strconv.Itoa(i.Port)
-	}
-	lb.Servers[0].Port = ""
-
-	if port == "" {
-		return errors.New("port is missing")
-	}
-
 	if i.Address == "" {
 		return errors.New("address is missing")
 	}
 
+	port := lb.Servers[0].Port
+	lb.Servers[0].Port = ""
+
+	if port == "" && i.Port > 0 {
+		port = strconv.Itoa(i.Port)
+	}
+
+	if port == "" {
+		return errors.New("port is missing")
+	}
+
 	lb.Servers[0].Address = net.JoinHostPort(i.Address, port)
+
 	return nil
 }
 
@@ -237,11 +233,6 @@ func (p *Provider) addServer(i item, lb *dynamic.ServersLoadBalancer) error {
 		return errors.New("load-balancer is missing")
 	}
 
-	var port string
-	if len(lb.Servers) > 0 {
-		port = lb.Servers[0].Port
-	}
-
 	if len(lb.Servers) == 0 {
 		server := dynamic.Server{}
 		server.SetDefaults()
@@ -249,19 +240,21 @@ func (p *Provider) addServer(i item, lb *dynamic.ServersLoadBalancer) error {
 		lb.Servers = []dynamic.Server{server}
 	}
 
-	if i.Port != 0 && port == "" {
+	if i.Address == "" {
+		return errors.New("address is missing")
+	}
+
+	port := lb.Servers[0].Port
+	lb.Servers[0].Port = ""
+
+	if port == "" && i.Port > 0 {
 		port = strconv.Itoa(i.Port)
 	}
-	lb.Servers[0].Port = ""
 
 	if port == "" {
 		return errors.New("port is missing")
 	}
 
-	if i.Address == "" {
-		return errors.New("address is missing")
-	}
-
 	scheme := lb.Servers[0].Scheme
 	lb.Servers[0].Scheme = ""
 	lb.Servers[0].URL = fmt.Sprintf("%s://%s", scheme, net.JoinHostPort(i.Address, port))

pkg/provider/rancher/config.go

@@ -160,7 +160,7 @@ func (p *Provider) keepService(ctx context.Context, service rancherData) bool {
 
 	matches, err := constraints.MatchLabels(service.Labels, p.Constraints)
 	if err != nil {
-		logger.Errorf("Error matching constraints expression: %v", err)
+		logger.Errorf("Error matching constraint expression: %v", err)
 		return false
 	}
 	if !matches {
@@ -185,23 +185,19 @@ func (p *Provider) keepService(ctx context.Context, service rancherData) bool {
 func (p *Provider) addServerTCP(ctx context.Context, service rancherData, loadBalancer *dynamic.TCPServersLoadBalancer) error {
 	log.FromContext(ctx).Debugf("Trying to add servers for service  %s \n", service.Name)
 
-	serverPort := ""
+	if loadBalancer == nil {
-
+		return errors.New("load-balancer is not defined")
-	if loadBalancer != nil && len(loadBalancer.Servers) > 0 {
-		serverPort = loadBalancer.Servers[0].Port
 	}
 
-	port := getServicePort(service)
-
 	if len(loadBalancer.Servers) == 0 {
-		server := dynamic.TCPServer{}
+		loadBalancer.Servers = []dynamic.TCPServer{{}}
-
-		loadBalancer.Servers = []dynamic.TCPServer{server}
 	}
 
-	if serverPort != "" {
+	port := loadBalancer.Servers[0].Port
-		port = serverPort
+	loadBalancer.Servers[0].Port = ""
-		loadBalancer.Servers[0].Port = ""
+
+	if port == "" {
+		port = getServicePort(service)
 	}
 
 	if port == "" {
@@ -216,29 +212,26 @@ func (p *Provider) addServerTCP(ctx context.Context, service rancherData, loadBa
 	}
 
 	loadBalancer.Servers = servers
+
 	return nil
 }
 
 func (p *Provider) addServerUDP(ctx context.Context, service rancherData, loadBalancer *dynamic.UDPServersLoadBalancer) error {
 	log.FromContext(ctx).Debugf("Trying to add servers for service  %s \n", service.Name)
 
-	serverPort := ""
+	if loadBalancer == nil {
-
+		return errors.New("load-balancer is not defined")
-	if loadBalancer != nil && len(loadBalancer.Servers) > 0 {
-		serverPort = loadBalancer.Servers[0].Port
 	}
 
-	port := getServicePort(service)
-
 	if len(loadBalancer.Servers) == 0 {
-		server := dynamic.UDPServer{}
+		loadBalancer.Servers = []dynamic.UDPServer{{}}
-
-		loadBalancer.Servers = []dynamic.UDPServer{server}
 	}
 
-	if serverPort != "" {
+	port := loadBalancer.Servers[0].Port
-		port = serverPort
+	loadBalancer.Servers[0].Port = ""
-		loadBalancer.Servers[0].Port = ""
+
+	if port == "" {
+		port = getServicePort(service)
 	}
 
 	if port == "" {
@@ -253,14 +246,16 @@ func (p *Provider) addServerUDP(ctx context.Context, service rancherData, loadBa
 	}
 
 	loadBalancer.Servers = servers
+
 	return nil
 }
 
 func (p *Provider) addServers(ctx context.Context, service rancherData, loadBalancer *dynamic.ServersLoadBalancer) error {
 	log.FromContext(ctx).Debugf("Trying to add servers for service  %s \n", service.Name)
 
-	serverPort := getLBServerPort(loadBalancer)
+	if loadBalancer == nil {
-	port := getServicePort(service)
+		return errors.New("load-balancer is not defined")
+	}
 
 	if len(loadBalancer.Servers) == 0 {
 		server := dynamic.Server{}
@@ -269,9 +264,11 @@ func (p *Provider) addServers(ctx context.Context, service rancherData, loadBala
 		loadBalancer.Servers = []dynamic.Server{server}
 	}
 
-	if serverPort != "" {
+	port := loadBalancer.Servers[0].Port
-		port = serverPort
+	loadBalancer.Servers[0].Port = ""
-		loadBalancer.Servers[0].Port = ""
+
+	if port == "" {
+		port = getServicePort(service)
 	}
 
 	if port == "" {
@@ -286,14 +283,8 @@ func (p *Provider) addServers(ctx context.Context, service rancherData, loadBala
 	}
 
 	loadBalancer.Servers = servers
-	return nil
-}
 
-func getLBServerPort(loadBalancer *dynamic.ServersLoadBalancer) string {
+	return nil
-	if loadBalancer != nil && len(loadBalancer.Servers) > 0 {
-		return loadBalancer.Servers[0].Port
-	}
-	return ""
 }
 
 func getServicePort(data rancherData) string {

pkg/server/service/proxy.go

@@ -15,6 +15,7 @@ import (
 	ptypes "github.com/traefik/paerser/types"
 	"github.com/traefik/traefik/v2/pkg/config/dynamic"
 	"github.com/traefik/traefik/v2/pkg/log"
+	"golang.org/x/net/http/httpguts"
 )
 
 // StatusClientClosedRequest non-standard HTTP status code for client disconnection.
@@ -67,16 +68,18 @@ func buildProxy(passHostHeader *bool, responseForwarding *dynamic.ResponseForwar
 			// some servers need Sec-WebSocket-Key, Sec-WebSocket-Extensions, Sec-WebSocket-Accept,
 			// Sec-WebSocket-Protocol and Sec-WebSocket-Version to be case-sensitive.
 			// https://tools.ietf.org/html/rfc6455#page-20
-			outReq.Header["Sec-WebSocket-Key"] = outReq.Header["Sec-Websocket-Key"]
+			if isWebSocketUpgrade(outReq) {
-			outReq.Header["Sec-WebSocket-Extensions"] = outReq.Header["Sec-Websocket-Extensions"]
+				outReq.Header["Sec-WebSocket-Key"] = outReq.Header["Sec-Websocket-Key"]
-			outReq.Header["Sec-WebSocket-Accept"] = outReq.Header["Sec-Websocket-Accept"]
+				outReq.Header["Sec-WebSocket-Extensions"] = outReq.Header["Sec-Websocket-Extensions"]
-			outReq.Header["Sec-WebSocket-Protocol"] = outReq.Header["Sec-Websocket-Protocol"]
+				outReq.Header["Sec-WebSocket-Accept"] = outReq.Header["Sec-Websocket-Accept"]
-			outReq.Header["Sec-WebSocket-Version"] = outReq.Header["Sec-Websocket-Version"]
+				outReq.Header["Sec-WebSocket-Protocol"] = outReq.Header["Sec-Websocket-Protocol"]
-			delete(outReq.Header, "Sec-Websocket-Key")
+				outReq.Header["Sec-WebSocket-Version"] = outReq.Header["Sec-Websocket-Version"]
-			delete(outReq.Header, "Sec-Websocket-Extensions")
+				delete(outReq.Header, "Sec-Websocket-Key")
-			delete(outReq.Header, "Sec-Websocket-Accept")
+				delete(outReq.Header, "Sec-Websocket-Extensions")
-			delete(outReq.Header, "Sec-Websocket-Protocol")
+				delete(outReq.Header, "Sec-Websocket-Accept")
-			delete(outReq.Header, "Sec-Websocket-Version")
+				delete(outReq.Header, "Sec-Websocket-Protocol")
+				delete(outReq.Header, "Sec-Websocket-Version")
+			}
 		},
 		Transport:     roundTripper,
 		FlushInterval: time.Duration(flushInterval),
@@ -112,6 +115,14 @@ func buildProxy(passHostHeader *bool, responseForwarding *dynamic.ResponseForwar
 	return proxy, nil
 }
 
+func isWebSocketUpgrade(req *http.Request) bool {
+	if !httpguts.HeaderValuesContainsToken(req.Header["Connection"], "Upgrade") {
+		return false
+	}
+
+	return strings.EqualFold(req.Header.Get("Upgrade"), "websocket")
+}
+
 func statusText(statusCode int) string {
 	if statusCode == StatusClientClosedRequest {
 		return StatusClientClosedRequestText