Add /version to server and check it in client.

Will help detect client/version skew and prevent e2e test from passing
while running a version other than the one you think it's running.

pkg/client/client.go

@@ -18,6 +18,7 @@ package client
 
 import (
 	"crypto/tls"
+	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -26,6 +27,7 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/version"
 	"github.com/golang/glog"
 )
 
@@ -238,3 +240,17 @@ func (c *Client) UpdateService(svc api.Service) (result api.Service, err error)
 func (c *Client) DeleteService(name string) error {
 	return c.Delete().Path("services").Path(name).Do().Error()
 }
+
+// ServerVersion retrieves and parses the server's version.
+func (c *Client) ServerVersion() (*version.Info, error) {
+	body, err := c.Get().AbsPath("/version").Do().Raw()
+	if err != nil {
+		return nil, err
+	}
+	var info version.Info
+	err = json.Unmarshal(body, &info)
+	if err != nil {
+		return nil, fmt.Errorf("Got '%s': %v", string(body), err)
+	}
+	return &info, nil
+}

pkg/client/client_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package client
 
 import (
+	"encoding/json"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -26,6 +27,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/version"
 )
 
 // TODO: Move this to a common place, it's needed in multiple tests.
@@ -456,3 +458,30 @@ func TestDoRequestAcceptedSuccess(t *testing.T) {
 	}
 	fakeHandler.ValidateRequest(t, "/foo/bar", "GET", nil)
 }
+
+func TestGetServerVersion(t *testing.T) {
+	expect := version.Info{
+		Major:     "foo",
+		Minor:     "bar",
+		GitCommit: "baz",
+	}
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		output, err := json.Marshal(expect)
+		if err != nil {
+			t.Errorf("unexpected encoding error: %v", err)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+		w.Write(output)
+	}))
+	client := New(server.URL, nil)
+
+	got, err := client.ServerVersion()
+	if err != nil {
+		t.Fatalf("unexpected encoding error: %v", err)
+	}
+	if e, a := expect, *got; !reflect.DeepEqual(e, a) {
+		t.Errorf("expected %v, got %v", e, a)
+	}
+}