From dca7363459d2e3a594dcdeaf2ae593f7cdead3c9 Mon Sep 17 00:00:00 2001
From: Daniel Smith <dbsmith@google.com>
Date: Tue, 28 Oct 2014 17:20:40 -0700
Subject: [PATCH] Serve API version list, test with an integration test.

---
 cmd/integration/integration.go | 12 ++++++++++++
 pkg/apiserver/apiserver.go     |  7 +++++++
 pkg/client/client.go           | 15 +++++++++++++++
 pkg/client/fake.go             |  5 +++++
 pkg/master/master.go           |  2 ++
 pkg/version/version.go         |  6 ++++++
 6 files changed, 47 insertions(+)

diff --git a/cmd/integration/integration.go b/cmd/integration/integration.go
index 373d1ccca405c..a29eb8c6a7192 100644
--- a/cmd/integration/integration.go
+++ b/cmd/integration/integration.go
@@ -251,6 +251,17 @@ func runReplicationControllerTest(c *client.Client) {
 	glog.Infof("Pods created")
 }
 
+func runAPIVersionsTest(c *client.Client) {
+	v, err := c.ServerAPIVersions()
+	if err != nil {
+		glog.Fatalf("failed to get api versions: %v", err)
+	}
+	if e, a := []string{"v1beta1", "v1beta2"}, v.Versions; !reflect.DeepEqual(e, a) {
+		glog.Fatalf("Expected version list '%v', got '%v'", e, a)
+	}
+	glog.Infof("Version test passed")
+}
+
 func runAtomicPutTest(c *client.Client) {
 	var svc api.Service
 	err := c.Post().Path("services").Body(
@@ -426,6 +437,7 @@ func main() {
 		runReplicationControllerTest,
 		runAtomicPutTest,
 		runServiceTest,
+		runAPIVersionsTest,
 	}
 	var wg sync.WaitGroup
 	wg.Add(len(testFuncs))
diff --git a/pkg/apiserver/apiserver.go b/pkg/apiserver/apiserver.go
index d1e565dcd8db9..1af55671bd6e6 100644
--- a/pkg/apiserver/apiserver.go
+++ b/pkg/apiserver/apiserver.go
@@ -135,6 +135,13 @@ func handleVersion(w http.ResponseWriter, req *http.Request) {
 	writeRawJSON(http.StatusOK, version.Get(), w)
 }
 
+// APIVersionHandler returns a handler which will list the provided versions as available.
+func APIVersionHandler(versions ...string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		writeRawJSON(http.StatusOK, version.APIVersions{Versions: versions}, w)
+	})
+}
+
 // writeJSON renders an object as JSON to the response.
 func writeJSON(statusCode int, codec runtime.Codec, object runtime.Object, w http.ResponseWriter) {
 	output, err := codec.Encode(object)
diff --git a/pkg/client/client.go b/pkg/client/client.go
index 367aaff3030a0..1773ab85775a9 100644
--- a/pkg/client/client.go
+++ b/pkg/client/client.go
@@ -62,6 +62,7 @@ func (c *Client) Services(namespace string) ServiceInterface {
 // VersionInterface has a method to retrieve the server version.
 type VersionInterface interface {
 	ServerVersion() (*version.Info, error)
+	ServerAPIVersions() (*version.APIVersions, error)
 }
 
 // APIStatus is exposed by errors that can be converted to an api.Status object
@@ -88,3 +89,17 @@ func (c *Client) ServerVersion() (*version.Info, error) {
 	}
 	return &info, nil
 }
+
+// ServerAPIVersions retrieves and parses the list of API versions the server supports.
+func (c *Client) ServerAPIVersions() (*version.APIVersions, error) {
+	body, err := c.Get().AbsPath("/api").Do().Raw()
+	if err != nil {
+		return nil, err
+	}
+	var v version.APIVersions
+	err = json.Unmarshal(body, &v)
+	if err != nil {
+		return nil, fmt.Errorf("Got '%s': %v", string(body), err)
+	}
+	return &v, nil
+}
diff --git a/pkg/client/fake.go b/pkg/client/fake.go
index 6c7135b3fe8f7..b7a508ad9eaea 100644
--- a/pkg/client/fake.go
+++ b/pkg/client/fake.go
@@ -70,3 +70,8 @@ func (c *Fake) ServerVersion() (*version.Info, error) {
 	versionInfo := version.Get()
 	return &versionInfo, nil
 }
+
+func (c *Fake) ServerAPIVersions() (*version.APIVersions, error) {
+	c.Actions = append(c.Actions, FakeAction{Action: "get-apiversions", Value: nil})
+	return &version.APIVersions{Versions: []string{"v1beta1", "v1beta2"}}, nil
+}
diff --git a/pkg/master/master.go b/pkg/master/master.go
index 627e5475bab7f..33ddc974e5831 100644
--- a/pkg/master/master.go
+++ b/pkg/master/master.go
@@ -190,6 +190,8 @@ func (m *Master) init(c *Config) {
 	}
 	apiserver.NewAPIGroup(m.API_v1beta1()).InstallREST(m.mux, c.APIPrefix+"/v1beta1")
 	apiserver.NewAPIGroup(m.API_v1beta2()).InstallREST(m.mux, c.APIPrefix+"/v1beta2")
+	versionHandler := apiserver.APIVersionHandler("v1beta1", "v1beta2")
+	m.mux.Handle(c.APIPrefix, versionHandler)
 	apiserver.InstallSupport(m.mux)
 	if c.EnableLogsSupport {
 		apiserver.InstallLogsSupport(m.mux)
diff --git a/pkg/version/version.go b/pkg/version/version.go
index 1343e4bde265d..5110d1a10ba51 100644
--- a/pkg/version/version.go
+++ b/pkg/version/version.go
@@ -45,3 +45,9 @@ func Get() Info {
 func (info Info) String() string {
 	return info.GitVersion
 }
+
+// APIVersions lists the api versions that are available, to allow
+// version negotiation.
+type APIVersions struct {
+	Versions []string `json:"versions" yaml:"versions"`
+}