create pkg/probe as successor to pkg/health.

pkg/probe/tcp/tcp.go

@@ -0,0 +1,46 @@
+/*
+Copyright 2015 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tcp
+
+import (
+	"net"
+	"strconv"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/probe"
+
+	"github.com/golang/glog"
+)
+
+func Probe(host string, port int) (probe.Status, error) {
+	return DoTCPProbe(net.JoinHostPort(host, strconv.Itoa(port)))
+}
+
+// DoTCPProbe checks that a TCP socket to the address can be opened.
+// If the socket can be opened, it returns Healthy.
+// If the socket fails to open, it returns Unhealthy.
+// This is exported because some other packages may want to do direct TCP probes.
+func DoTCPProbe(addr string) (probe.Status, error) {
+	conn, err := net.Dial("tcp", addr)
+	if err != nil {
+		return probe.Unhealthy, nil
+	}
+	err = conn.Close()
+	if err != nil {
+		glog.Errorf("unexpected error closing health check socket: %v (%#v)", err, err)
+	}
+	return probe.Healthy, nil
+}