Masquerade traffic from off-cluster going through kube-proxy.

cluster/saltbase/salt/kube-proxy/kube-proxy.manifest

@@ -14,6 +14,10 @@
 {% if pillar['kubeproxy_test_args'] is defined -%}
   {% set test_args=pillar['kubeproxy_test_args'] %}
 {% endif -%}
+{% set cluster_cidr = "" -%}
+{% if pillar['cluster_cidr'] is defined -%}
+  {% set cluster_cidr=" --cluster-cidr=" + pillar['cluster_cidr'] %}
+{% endif -%}
 
 {% set log_level = pillar['log_level'] -%}
 {% if pillar['kubeproxy_test_log_level'] is defined -%}
@@ -40,7 +44,7 @@ spec:
     command:
     - /bin/sh
     - -c
-    - kube-proxy {{api_servers_with_port}} {{kubeconfig}} --resource-container="" {{log_level}} {{test_args}} 1>>/var/log/kube-proxy.log 2>&1
+    - kube-proxy {{api_servers_with_port}} {{kubeconfig}} {{cluster_cidr}} --resource-container="" {{log_level}} {{test_args}} 1>>/var/log/kube-proxy.log 2>&1
     securityContext:
       privileged: true
     volumeMounts:

cmd/kube-proxy/app/options/options.go

@@ -75,6 +75,7 @@ func (s *ProxyServerConfig) AddFlags(fs *pflag.FlagSet) {
 	fs.DurationVar(&s.IPTablesSyncPeriod.Duration, "iptables-sync-period", s.IPTablesSyncPeriod.Duration, "How often iptables rules are refreshed (e.g. '5s', '1m', '2h22m').  Must be greater than 0.")
 	fs.DurationVar(&s.ConfigSyncPeriod, "config-sync-period", s.ConfigSyncPeriod, "How often configuration from the apiserver is refreshed.  Must be greater than 0.")
 	fs.BoolVar(&s.MasqueradeAll, "masquerade-all", s.MasqueradeAll, "If using the pure iptables proxy, SNAT everything")
+	fs.StringVar(&s.ClusterCIDR, "cluster-cidr", s.ClusterCIDR, "The CIDR range of pods in the cluster. It is used to bridge traffic coming from outside of the cluster. If not provided, no off-cluster bridging will be performed.")
 	fs.BoolVar(&s.CleanupAndExit, "cleanup-iptables", s.CleanupAndExit, "If true cleanup iptables rules and exit.")
 	fs.Float32Var(&s.KubeAPIQPS, "kube-api-qps", s.KubeAPIQPS, "QPS to use while talking with kubernetes apiserver")
 	fs.IntVar(&s.KubeAPIBurst, "kube-api-burst", s.KubeAPIBurst, "Burst to use while talking with kubernetes apiserver")

cmd/kube-proxy/app/server.go

@@ -203,7 +203,7 @@ func NewProxyServerDefault(config *options.ProxyServerConfig) (*ProxyServer, err
 			return nil, fmt.Errorf("Unable to read IPTablesMasqueradeBit from config")
 		}
 
-		proxierIptables, err := iptables.NewProxier(iptInterface, execer, config.IPTablesSyncPeriod.Duration, config.MasqueradeAll, *config.IPTablesMasqueradeBit)
+		proxierIptables, err := iptables.NewProxier(iptInterface, execer, config.IPTablesSyncPeriod.Duration, config.MasqueradeAll, *config.IPTablesMasqueradeBit, config.ClusterCIDR)
 		if err != nil {
 			glog.Fatalf("Unable to create proxier: %v", err)
 		}

docs/admin/kube-proxy.md

@@ -56,6 +56,7 @@ kube-proxy
 ```
       --bind-address=0.0.0.0: The IP address for the proxy server to serve on (set to 0.0.0.0 for all interfaces)
       --cleanup-iptables[=false]: If true cleanup iptables rules and exit.
+      --cluster-cidr="": The CIDR range of pods in the cluster. It is used to bridge traffic coming from outside of the cluster. If not provided, no off-cluster bridging will be performed.
       --config-sync-period=15m0s: How often configuration from the apiserver is refreshed.  Must be greater than 0.
       --conntrack-max=262144: Maximum number of NAT connections to track (0 to leave as-is)
       --conntrack-tcp-timeout-established=24h0m0s: Idle timeout for established TCP connections (0 to leave as-is)
@@ -77,7 +78,7 @@ kube-proxy
       --udp-timeout=250ms: How long an idle UDP connection will be kept open (e.g. '250ms', '2s').  Must be greater than 0. Only applicable for proxy-mode=userspace
 ```
 
-###### Auto generated by spf13/cobra on 7-Feb-2016
+###### Auto generated by spf13/cobra on 18-Apr-2016
 
 
 <!-- BEGIN MUNGE: GENERATED_ANALYTICS -->

hack/verify-flags/exceptions.txt

@@ -33,6 +33,7 @@ cluster/saltbase/salt/kube-apiserver/kube-apiserver.manifest:{% set params = add
 cluster/saltbase/salt/kube-controller-manager/kube-controller-manager.manifest:{% set params = "--master=127.0.0.1:8080" + " " + cluster_name + " " + cluster_cidr + " " + allocate_node_cidrs + " " + terminated_pod_gc + " " + cloud_provider  + " " + cloud_config + " " + service_account_key + " " + log_level + " " + root_ca_file -%}
 cluster/saltbase/salt/kube-proxy/kube-proxy.manifest:  {% set api_servers_with_port = api_servers + ":6443" -%}
 cluster/saltbase/salt/kube-proxy/kube-proxy.manifest:  {% set api_servers_with_port = api_servers -%}
+cluster/saltbase/salt/kube-proxy/kube-proxy.manifest:  {% set cluster_cidr=" --cluster-cidr=" + pillar['cluster_cidr'] %}
 cluster/saltbase/salt/kubelet/default:  {% set api_servers_with_port = api_servers + ":6443" -%}
 cluster/saltbase/salt/kubelet/default:  {% set api_servers_with_port = api_servers -%}
 cluster/saltbase/salt/kubelet/default:  {% set enable_custom_metrics="--enable-custom-metrics=" + pillar['enable_custom_metrics'] %}

pkg/apis/componentconfig/deep_copy_generated.go

@@ -138,6 +138,7 @@ func DeepCopy_componentconfig_KubeProxyConfiguration(in KubeProxyConfiguration,
 		return err
 	}
 	out.BindAddress = in.BindAddress
+	out.ClusterCIDR = in.ClusterCIDR
 	out.HealthzBindAddress = in.HealthzBindAddress
 	out.HealthzPort = in.HealthzPort
 	out.HostnameOverride = in.HostnameOverride

pkg/apis/componentconfig/types.go

@@ -24,6 +24,10 @@ type KubeProxyConfiguration struct {
 	// bindAddress is the IP address for the proxy server to serve on (set to 0.0.0.0
 	// for all interfaces)
 	BindAddress string `json:"bindAddress"`
+	// clusterCIDR is the CIDR range of the pods in the cluster. It is used to
+	// bridge traffic coming from outside of the cluster. If not provided,
+	// no off-cluster bridging will be performed.
+	ClusterCIDR string `json:"clusterCIDR"`
 	// healthzBindAddress is the IP address for the health check server to serve on,
 	// defaulting to 127.0.0.1 (set to 0.0.0.0 for all interfaces)
 	HealthzBindAddress string `json:"healthzBindAddress"`

pkg/apis/componentconfig/v1alpha1/conversion_generated.go

@@ -49,6 +49,7 @@ func autoConvert_v1alpha1_KubeProxyConfiguration_To_componentconfig_KubeProxyCon
 		return err
 	}
 	out.BindAddress = in.BindAddress
+	out.ClusterCIDR = in.ClusterCIDR
 	out.HealthzBindAddress = in.HealthzBindAddress
 	out.HealthzPort = int(in.HealthzPort)
 	out.HostnameOverride = in.HostnameOverride
@@ -100,6 +101,7 @@ func autoConvert_componentconfig_KubeProxyConfiguration_To_v1alpha1_KubeProxyCon
 		return err
 	}
 	out.BindAddress = in.BindAddress
+	out.ClusterCIDR = in.ClusterCIDR
 	out.HealthzBindAddress = in.HealthzBindAddress
 	out.HealthzPort = int32(in.HealthzPort)
 	out.HostnameOverride = in.HostnameOverride

pkg/apis/componentconfig/v1alpha1/deep_copy_generated.go

@@ -42,6 +42,7 @@ func DeepCopy_v1alpha1_KubeProxyConfiguration(in KubeProxyConfiguration, out *Ku
 		return err
 	}
 	out.BindAddress = in.BindAddress
+	out.ClusterCIDR = in.ClusterCIDR
 	out.HealthzBindAddress = in.HealthzBindAddress
 	out.HealthzPort = in.HealthzPort
 	out.HostnameOverride = in.HostnameOverride

pkg/apis/componentconfig/v1alpha1/types.go

@@ -24,6 +24,10 @@ type KubeProxyConfiguration struct {
 	// bindAddress is the IP address for the proxy server to serve on (set to 0.0.0.0
 	// for all interfaces)
 	BindAddress string `json:"bindAddress"`
+	// clusterCIDR is the CIDR range of the pods in the cluster. It is used to
+	// bridge traffic coming from outside of the cluster. If not provided,
+	// no off-cluster bridging will be performed.
+	ClusterCIDR string `json:"clusterCIDR"`
 	// healthzBindAddress is the IP address for the health check server to serve on,
 	// defaulting to 127.0.0.1 (set to 0.0.0.0 for all interfaces)
 	HealthzBindAddress string `json:"healthzBindAddress"`

pkg/proxy/iptables/proxier.go

@@ -162,6 +162,7 @@ type Proxier struct {
 	masqueradeAll  bool
 	masqueradeMark string
 	exec           utilexec.Interface
+	clusterCIDR    string
 }
 
 type localPort struct {
@@ -187,7 +188,7 @@ var _ proxy.ProxyProvider = &Proxier{}
 // An error will be returned if iptables fails to update or acquire the initial lock.
 // Once a proxier is created, it will keep iptables up to date in the background and
 // will not terminate if a particular iptables call fails.
-func NewProxier(ipt utiliptables.Interface, exec utilexec.Interface, syncPeriod time.Duration, masqueradeAll bool, masqueradeBit int) (*Proxier, error) {
+func NewProxier(ipt utiliptables.Interface, exec utilexec.Interface, syncPeriod time.Duration, masqueradeAll bool, masqueradeBit int, clusterCIDR string) (*Proxier, error) {
 	// Set the route_localnet sysctl we need for
 	if err := utilsysctl.SetSysctl(sysctlRouteLocalnet, 1); err != nil {
 		return nil, fmt.Errorf("can't set sysctl %s: %v", sysctlRouteLocalnet, err)
@@ -223,6 +224,7 @@ func NewProxier(ipt utiliptables.Interface, exec utilexec.Interface, syncPeriod
 		masqueradeAll:  masqueradeAll,
 		masqueradeMark: masqueradeMark,
 		exec:           exec,
+		clusterCIDR:    clusterCIDR,
 	}, nil
 }
 
@@ -792,6 +794,9 @@ func (proxier *Proxier) syncProxyRules() {
 		if proxier.masqueradeAll {
 			writeLine(natRules, append(args, "-j", string(kubeMarkMasqChain))...)
 		}
+		if len(proxier.clusterCIDR) > 0 {
+			writeLine(natRules, append(args, "! -s", proxier.clusterCIDR, "-j", string(kubeMarkMasqChain))...)
+		}
 		writeLine(natRules, append(args, "-j", string(svcChain))...)
 
 		// Capture externalIPs.