Merge pull request #36079 from apprenda/windows_kube_proxy

Automatic merge from submit-queue

Add Windows support to kube-proxy

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**What this PR does / why we need it**:
This is the first stab at supporting kube-proxy (userspace mode) on Windows

**Which issue this PR fixes** : 
fixes #30278

**Special notes for your reviewer**:
The MVP uses `netsh portproxy` to redirect traffic from `ServiceIP:ServicePort` to a `LocalIP:LocalPort`. 
For the next version we are expecting to have guidance from Microsoft Container Networking team.

**Limitations**:
Current implementation does not support DNS queries over UDP as `netsh portproxy` currently only supports TCP. We are working with Microsoft to remediate this.

cc: @brendandburns @dcbw 

**Release note**:
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cmd/kube-proxy/app/BUILD

@@ -29,6 +29,7 @@ go_library(
         "//pkg/proxy/config:go_default_library",
         "//pkg/proxy/iptables:go_default_library",
         "//pkg/proxy/userspace:go_default_library",
+        "//pkg/proxy/winuserspace:go_default_library",
         "//pkg/types:go_default_library",
         "//pkg/util/configz:go_default_library",
         "//pkg/util/dbus:go_default_library",
@@ -36,6 +37,7 @@ go_library(
         "//pkg/util/iptables:go_default_library",
         "//pkg/util/mount:go_default_library",
         "//pkg/util/net:go_default_library",
+        "//pkg/util/netsh:go_default_library",
         "//pkg/util/node:go_default_library",
         "//pkg/util/oom:go_default_library",
         "//pkg/util/resourcecontainer:go_default_library",

cmd/kube-proxy/app/server.go

@@ -39,12 +39,14 @@ import (
 	proxyconfig "k8s.io/kubernetes/pkg/proxy/config"
 	"k8s.io/kubernetes/pkg/proxy/iptables"
 	"k8s.io/kubernetes/pkg/proxy/userspace"
+	"k8s.io/kubernetes/pkg/proxy/winuserspace"
 	"k8s.io/kubernetes/pkg/types"
 	"k8s.io/kubernetes/pkg/util/configz"
 	utildbus "k8s.io/kubernetes/pkg/util/dbus"
 	"k8s.io/kubernetes/pkg/util/exec"
 	utiliptables "k8s.io/kubernetes/pkg/util/iptables"
 	utilnet "k8s.io/kubernetes/pkg/util/net"
+	utilnetsh "k8s.io/kubernetes/pkg/util/netsh"
 	nodeutil "k8s.io/kubernetes/pkg/util/node"
 	"k8s.io/kubernetes/pkg/util/oom"
 	"k8s.io/kubernetes/pkg/util/resourcecontainer"
@@ -136,10 +138,19 @@ func NewProxyServerDefault(config *options.ProxyServerConfig) (*ProxyServer, err
 		protocol = utiliptables.ProtocolIpv6
 	}
 
+	var netshInterface utilnetsh.Interface
+	var iptInterface utiliptables.Interface
+	var dbus utildbus.Interface
+
 	// Create a iptables utils.
 	execer := exec.New()
-	dbus := utildbus.New()
-	iptInterface := utiliptables.New(execer, dbus, protocol)
+
+	if runtime.GOOS == "windows" {
+		netshInterface = utilnetsh.New(execer)
+	} else {
+		dbus = utildbus.New()
+		iptInterface = utiliptables.New(execer, dbus, protocol)
+	}
 
 	// We omit creation of pretty much everything if we run in cleanup mode
 	if config.CleanupAndExit {
@@ -223,24 +234,44 @@ func NewProxyServerDefault(config *options.ProxyServerConfig) (*ProxyServer, err
 		// set EndpointsConfigHandler to our loadBalancer
 		endpointsHandler = loadBalancer
 
-		proxierUserspace, err := userspace.NewProxier(
-			loadBalancer,
-			net.ParseIP(config.BindAddress),
-			iptInterface,
-			*utilnet.ParsePortRangeOrDie(config.PortRange),
-			config.IPTablesSyncPeriod.Duration,
-			config.IPTablesMinSyncPeriod.Duration,
-			config.UDPIdleTimeout.Duration,
-		)
+		var proxierUserspace proxy.ProxyProvider
+
+		if runtime.GOOS == "windows" {
+			proxierUserspace, err = winuserspace.NewProxier(
+				loadBalancer,
+				net.ParseIP(config.BindAddress),
+				netshInterface,
+				*utilnet.ParsePortRangeOrDie(config.PortRange),
+				// TODO @pires replace below with default values, if applicable
+				config.IPTablesSyncPeriod.Duration,
+				config.UDPIdleTimeout.Duration,
+			)
+		} else {
+			proxierUserspace, err = userspace.NewProxier(
+				loadBalancer,
+				net.ParseIP(config.BindAddress),
+				iptInterface,
+				*utilnet.ParsePortRangeOrDie(config.PortRange),
+				config.IPTablesSyncPeriod.Duration,
+				config.IPTablesMinSyncPeriod.Duration,
+				config.UDPIdleTimeout.Duration,
+			)
+		}
 		if err != nil {
 			glog.Fatalf("Unable to create proxier: %v", err)
 		}
 		proxier = proxierUserspace
-		// Remove artifacts from the pure-iptables Proxier.
-		glog.V(0).Info("Tearing down pure-iptables proxy rules.")
-		iptables.CleanupLeftovers(iptInterface)
+		// Remove artifacts from the pure-iptables Proxier, if not on Windows.
+		if runtime.GOOS != "windows" {
+			glog.V(0).Info("Tearing down pure-iptables proxy rules.")
+			iptables.CleanupLeftovers(iptInterface)
+		}
+	}
+
+	// Add iptables reload function, if not on Windows.
+	if runtime.GOOS != "windows" {
+		iptInterface.AddReloadFunc(proxier.Sync)
 	}
-	iptInterface.AddReloadFunc(proxier.Sync)
 
 	// Create configs (i.e. Watches for Services and Endpoints)
 	// Note: RegisterHandler() calls need to happen before creation of Sources because sources
@@ -300,7 +331,7 @@ func (s *ProxyServer) Run() error {
 	}
 
 	// Tune conntrack, if requested
-	if s.Conntracker != nil {
+	if s.Conntracker != nil && runtime.GOOS != "windows" {
 		max, err := getConntrackMax(s.Config)
 		if err != nil {
 			return err