Feature: add udp timeout configuration

docs/content/reference/static-configuration/cli-ref.md

@@ -171,6 +171,9 @@ ReadTimeout is the maximum duration for reading the entire request, including th
 `--entrypoints.<name>.transport.respondingtimeouts.writetimeout`:  
 WriteTimeout is the maximum duration before timing out writes of the response. If zero, no timeout is set. (Default: ```0```)
 
+`--entrypoints.<name>.udp.timeout`:  
+Timeout defines how long to wait on an idle session before releasing the related resources. (Default: ```3```)
+
 `--experimental.devplugin.gopath`:  
 plugin's GOPATH.
 

docs/content/reference/static-configuration/env-ref.md

@@ -171,6 +171,9 @@ ReadTimeout is the maximum duration for reading the entire request, including th
 `TRAEFIK_ENTRYPOINTS_<NAME>_TRANSPORT_RESPONDINGTIMEOUTS_WRITETIMEOUT`:  
 WriteTimeout is the maximum duration before timing out writes of the response. If zero, no timeout is set. (Default: ```0```)
 
+`TRAEFIK_ENTRYPOINTS_<NAME>_UDP_TIMEOUT`:  
+Timeout defines how long to wait on an idle session before releasing the related resources. (Default: ```3```)
+
 `TRAEFIK_EXPERIMENTAL_DEVPLUGIN_GOPATH`:  
 plugin's GOPATH.
 

docs/content/reference/static-configuration/file.toml

@@ -29,6 +29,8 @@
     [entryPoints.EntryPoint0.forwardedHeaders]
       insecure = true
       trustedIPs = ["foobar", "foobar"]
+    [entryPoints.EntryPoint0.udp]
+      timeout = 42
     [entryPoints.EntryPoint0.http]
       middlewares = ["foobar", "foobar"]
       [entryPoints.EntryPoint0.http.redirections]

docs/content/reference/static-configuration/file.yaml

@@ -33,6 +33,8 @@ entryPoints:
       - foobar
       - foobar
     enableHTTP3: true
+    udp:
+      timeout: 42
     http:
       redirections:
         entryPoint:

docs/content/routing/entrypoints.md

@@ -864,3 +864,35 @@ entryPoints:
     --entrypoints.websecure.address=:443
     --entrypoints.websecure.http.tls.certResolver=leresolver
     ```
+
+## UDP Options
+
+This whole section is dedicated to options, keyed by entry point, that will apply only to UDP routing.
+
+### Timeout
+
+_Optional, Default=3s_
+
+Timeout defines how long to wait on an idle session before releasing the related resources.
+The Timeout value must be greater than zero.
+
+```toml tab="File (TOML)"
+[entryPoints.foo]
+  address = ":8000/udp"
+
+    [entryPoints.foo.udp]
+      timeout = "10s"
+```
+
+```yaml tab="File (YAML)"
+entryPoints:
+  foo:
+    address: ':8000/udp'
+    udp:
+      timeout: 10s
+```
+
+```bash tab="CLI"
+entrypoints.foo.address=:8000/udp
+entrypoints.foo.udp.timeout=10s
+```

docs/content/routing/routers/index.md

@@ -982,8 +982,9 @@ So UDP "routers" at this time are pretty much only load-balancers in one form or
 	It basically means that some state is kept about an ongoing communication between a client and a backend,
 	notably so that the proxy knows where to forward a response packet from a backend.
 	As expected, a `timeout` is associated to each of these sessions,
-	so that they get cleaned out if they go through a period of inactivity longer than a given duration (that is hardcoded to 3 seconds for now).
-	Making this timeout configurable will be considered later if we get more usage feedback on this matter.
+	so that they get cleaned out if they go through a period of inactivity longer than a given duration. 
+	Timeout can be configured using the `entryPoints.name.udp.timeout` option as described 
+	under [entry points](../entrypoints/#udp-options).
 
 ### EntryPoints
 

pkg/config/static/entrypoints.go

@@ -5,6 +5,7 @@ import (
 	"math"
 	"strings"
 
+	ptypes "github.com/traefik/paerser/types"
 	"github.com/traefik/traefik/v2/pkg/types"
 )
 
@@ -16,6 +17,7 @@ type EntryPoint struct {
 	ForwardedHeaders *ForwardedHeaders     `description:"Trust client forwarding headers." json:"forwardedHeaders,omitempty" toml:"forwardedHeaders,omitempty" yaml:"forwardedHeaders,omitempty" export:"true"`
 	HTTP             HTTPConfig            `description:"HTTP configuration." json:"http,omitempty" toml:"http,omitempty" yaml:"http,omitempty" export:"true"`
 	EnableHTTP3      bool                  `description:"Enable HTTP3." json:"enableHTTP3,omitempty" toml:"enableHTTP3,omitempty" yaml:"enableHTTP3,omitempty" export:"true"`
+	UDP              *UDPConfig            `description:"UDP configuration." json:"udp,omitempty" toml:"udp,omitempty" yaml:"udp,omitempty"`
 }
 
 // GetAddress strips any potential protocol part of the address field of the
@@ -46,6 +48,8 @@ func (ep *EntryPoint) SetDefaults() {
 	ep.Transport = &EntryPointsTransport{}
 	ep.Transport.SetDefaults()
 	ep.ForwardedHeaders = &ForwardedHeaders{}
+	ep.UDP = &UDPConfig{}
+	ep.UDP.SetDefaults()
 }
 
 // HTTPConfig is the HTTP configuration of an entry point.
@@ -110,3 +114,13 @@ func (t *EntryPointsTransport) SetDefaults() {
 	t.RespondingTimeouts = &RespondingTimeouts{}
 	t.RespondingTimeouts.SetDefaults()
 }
+
+// UDPConfig is the UDP configuration of an entry point.
+type UDPConfig struct {
+	Timeout ptypes.Duration `description:"Timeout defines how long to wait on an idle session before releasing the related resources." json:"timeout,omitempty" toml:"timeout,omitempty" yaml:"timeout,omitempty"`
+}
+
+// SetDefaults sets the default values.
+func (u *UDPConfig) SetDefaults() {
+	u.Timeout = ptypes.Duration(DefaultUDPTimeout)
+}

pkg/config/static/static_config.go

@@ -51,6 +51,10 @@ const (
 
 	// DefaultAcmeCAServer is the default ACME API endpoint.
 	DefaultAcmeCAServer = "https://acme-v02.api.letsencrypt.org/directory"
+
+	// DefaultUDPTimeout defines how long to wait by default on an idle session,
+	// before releasing all resources related to that session.
+	DefaultUDPTimeout = 3 * time.Second
 )
 
 // Configuration is the static configuration.

pkg/server/server_entrypoint_udp.go

@@ -89,7 +89,8 @@ func NewUDPEntryPoint(cfg *static.EntryPoint) (*UDPEntryPoint, error) {
 	if err != nil {
 		return nil, err
 	}
-	listener, err := udp.Listen("udp", addr)
+
+	listener, err := udp.Listen("udp", addr, time.Duration(cfg.UDP.Timeout))
 	if err != nil {
 		return nil, err
 	}

pkg/server/server_entrypoint_udp_test.go

@@ -14,14 +14,17 @@ import (
 )
 
 func TestShutdownUDPConn(t *testing.T) {
-	entryPoint, err := NewUDPEntryPoint(&static.EntryPoint{
+	ep := static.EntryPoint{
 		Address: ":0",
 		Transport: &static.EntryPointsTransport{
 			LifeCycle: &static.LifeCycle{
 				GraceTimeOut: ptypes.Duration(5 * time.Second),
 			},
 		},
-	})
+	}
+	ep.SetDefaults()
+
+	entryPoint, err := NewUDPEntryPoint(&ep)
 	require.NoError(t, err)
 
 	go entryPoint.Start(context.Background())

pkg/udp/conn.go

@@ -12,12 +12,6 @@ const receiveMTU = 8192
 
 const closeRetryInterval = 500 * time.Millisecond
 
-// connTimeout determines how long to wait on an idle session,
-// before releasing all resources related to that session.
-const connTimeout = 3 * time.Second
-
-var timeoutTicker = connTimeout / 10
-
 var errClosedListener = errors.New("udp: listener closed")
 
 // Listener augments a session-oriented Listener over a UDP PacketConn.
@@ -31,10 +25,18 @@ type Listener struct {
 	accepting bool
 
 	acceptCh chan *Conn // no need for a Once, already indirectly guarded by accepting.
+
+	// timeout defines how long to wait on an idle session,
+	// before releasing its related resources.
+	timeout time.Duration
 }
 
 // Listen creates a new listener.
-func Listen(network string, laddr *net.UDPAddr) (*Listener, error) {
+func Listen(network string, laddr *net.UDPAddr, timeout time.Duration) (*Listener, error) {
+	if timeout <= 0 {
+		return nil, errors.New("timeout should be greater than zero")
+	}
+
 	conn, err := net.ListenUDP(network, laddr)
 	if err != nil {
 		return nil, err
@@ -45,6 +47,7 @@ func Listen(network string, laddr *net.UDPAddr) (*Listener, error) {
 		acceptCh:  make(chan *Conn),
 		conns:     make(map[string]*Conn),
 		accepting: true,
+		timeout:   timeout,
 	}
 
 	go l.readLoop()
@@ -179,7 +182,7 @@ func (l *Listener) newConn(rAddr net.Addr) *Conn {
 		readCh:    make(chan []byte),
 		sizeCh:    make(chan int),
 		doneCh:    make(chan struct{}),
-		timeout:   timeoutTicker,
+		timeout:   l.timeout,
 	}
 }
 
@@ -206,7 +209,7 @@ type Conn struct {
 // that is to say it waits on readCh to receive the slice of bytes that the Read operation wants to read onto.
 // The Read operation receives the signal that the data has been written to the slice of bytes through the sizeCh.
 func (c *Conn) readLoop() {
-	ticker := time.NewTicker(c.timeout)
+	ticker := time.NewTicker(c.timeout / 10)
 	defer ticker.Stop()
 
 	for {
@@ -216,7 +219,7 @@ func (c *Conn) readLoop() {
 				c.msgs = append(c.msgs, msg)
 			case <-ticker.C:
 				c.muActivity.RLock()
-				deadline := c.lastActivity.Add(connTimeout)
+				deadline := c.lastActivity.Add(c.timeout)
 				c.muActivity.RUnlock()
 				if time.Now().After(deadline) {
 					c.Close()
@@ -236,7 +239,7 @@ func (c *Conn) readLoop() {
 			c.msgs = append(c.msgs, msg)
 		case <-ticker.C:
 			c.muActivity.RLock()
-			deadline := c.lastActivity.Add(connTimeout)
+			deadline := c.lastActivity.Add(c.timeout)
 			c.muActivity.RUnlock()
 			if time.Now().After(deadline) {
 				c.Close()

pkg/udp/conn_test.go

@@ -15,7 +15,7 @@ func TestConsecutiveWrites(t *testing.T) {
 	addr, err := net.ResolveUDPAddr("udp", ":0")
 	require.NoError(t, err)
 
-	ln, err := Listen("udp", addr)
+	ln, err := Listen("udp", addr, 3*time.Second)
 	require.NoError(t, err)
 	defer func() {
 		err := ln.Close()
@@ -77,7 +77,7 @@ func TestListenNotBlocking(t *testing.T) {
 
 	require.NoError(t, err)
 
-	ln, err := Listen("udp", addr)
+	ln, err := Listen("udp", addr, 3*time.Second)
 	require.NoError(t, err)
 	defer func() {
 		err := ln.Close()
@@ -162,6 +162,14 @@ func TestListenNotBlocking(t *testing.T) {
 	}
 }
 
+func TestListenWithZeroTimeout(t *testing.T) {
+	addr, err := net.ResolveUDPAddr("udp", ":0")
+	require.NoError(t, err)
+
+	_, err = Listen("udp", addr, 0)
+	assert.Error(t, err)
+}
+
 func TestTimeoutWithRead(t *testing.T) {
 	testTimeout(t, true)
 }
@@ -176,7 +184,7 @@ func testTimeout(t *testing.T, withRead bool) {
 	addr, err := net.ResolveUDPAddr("udp", ":0")
 	require.NoError(t, err)
 
-	ln, err := Listen("udp", addr)
+	ln, err := Listen("udp", addr, 3*time.Second)
 	require.NoError(t, err)
 	defer func() {
 		err := ln.Close()
@@ -212,7 +220,7 @@ func testTimeout(t *testing.T, withRead bool) {
 
 	assert.Equal(t, 10, len(ln.conns))
 
-	time.Sleep(4 * time.Second)
+	time.Sleep(ln.timeout + time.Second)
 	assert.Equal(t, 0, len(ln.conns))
 }
 
@@ -220,7 +228,7 @@ func TestShutdown(t *testing.T) {
 	addr, err := net.ResolveUDPAddr("udp", ":0")
 	require.NoError(t, err)
 
-	l, err := Listen("udp", addr)
+	l, err := Listen("udp", addr, 3*time.Second)
 	require.NoError(t, err)
 
 	go func() {

pkg/udp/proxy_test.go

@@ -46,7 +46,7 @@ func newServer(t *testing.T, addr string, handler Handler) {
 	addrL, err := net.ResolveUDPAddr("udp", addr)
 	require.NoError(t, err)
 
-	listener, err := Listen("udp", addrL)
+	listener, err := Listen("udp", addrL, 3*time.Second)
 	require.NoError(t, err)
 
 	for {