Rector kubelet stats serving

Changes include:
- Moving stats serving & routes to pkg/kubelet/server/stats/handler.go
- Managing the routes with restful.WebService, rather than manual
parsing
- Misc cleanup

These changes will make adding the new routes for /stats/summary more
manageable.

pkg/kubelet/server/stats/handler.go

@@ -0,0 +1,220 @@
+/*
+Copyright 2016 The Kubernetes Authors 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 stats
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"path"
+	"time"
+
+	"github.com/emicklei/go-restful"
+	"github.com/golang/glog"
+	cadvisorapi "github.com/google/cadvisor/info/v1"
+
+	"k8s.io/kubernetes/pkg/api"
+	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+	"k8s.io/kubernetes/pkg/types"
+)
+
+// Host methods required by stats handlers.
+type StatsProvider interface {
+	GetContainerInfo(podFullName string, uid types.UID, containerName string, req *cadvisorapi.ContainerInfoRequest) (*cadvisorapi.ContainerInfo, error)
+	GetRawContainerInfo(containerName string, req *cadvisorapi.ContainerInfoRequest, subcontainers bool) (map[string]*cadvisorapi.ContainerInfo, error)
+	GetPodByName(namespace, name string) (*api.Pod, bool)
+}
+
+type handler struct {
+	provider StatsProvider
+}
+
+func CreateHandlers(provider StatsProvider) *restful.WebService {
+	h := &handler{provider}
+
+	ws := &restful.WebService{}
+	ws.Path("/stats/").
+		Produces(restful.MIME_JSON)
+
+	endpoints := []struct {
+		path    string
+		handler restful.RouteFunction
+	}{
+		{"", h.handleStats},
+		{"/container", h.handleSystemContainer},
+		{"/{podName}/{containerName}", h.handlePodContainer},
+		{"/{namespace}/{podName}/{uid}/{containerName}", h.handlePodContainer},
+	}
+
+	for _, e := range endpoints {
+		for _, method := range []string{"GET", "POST"} {
+			ws.Route(ws.
+				Method(method).
+				Path(e.path).
+				To(e.handler))
+		}
+	}
+
+	return ws
+}
+
+type StatsRequest struct {
+	// The name of the container for which to request stats.
+	// Default: /
+	ContainerName string `json:"containerName,omitempty"`
+
+	// Max number of stats to return.
+	// If start and end time are specified this limit is ignored.
+	// Default: 60
+	NumStats int `json:"num_stats,omitempty"`
+
+	// Start time for which to query information.
+	// If omitted, the beginning of time is assumed.
+	Start time.Time `json:"start,omitempty"`
+
+	// End time for which to query information.
+	// If omitted, current time is assumed.
+	End time.Time `json:"end,omitempty"`
+
+	// Whether to also include information from subcontainers.
+	// Default: false.
+	Subcontainers bool `json:"subcontainers,omitempty"`
+}
+
+func (r *StatsRequest) cadvisorRequest() *cadvisorapi.ContainerInfoRequest {
+	return &cadvisorapi.ContainerInfoRequest{
+		NumStats: r.NumStats,
+		Start:    r.Start,
+		End:      r.End,
+	}
+}
+
+func parseStatsRequest(request *restful.Request) (StatsRequest, error) {
+	// Default request.
+	query := StatsRequest{
+		NumStats: 60,
+	}
+
+	err := json.NewDecoder(request.Request.Body).Decode(&query)
+	if err != nil && err != io.EOF {
+		return query, err
+	}
+	return query, nil
+}
+
+// Handles root container stats requests to /stats
+func (h *handler) handleStats(request *restful.Request, response *restful.Response) {
+	query, err := parseStatsRequest(request)
+	if err != nil {
+		handleError(response, err)
+		return
+	}
+
+	// Root container stats.
+	statsMap, err := h.provider.GetRawContainerInfo("/", query.cadvisorRequest(), false)
+	if err != nil {
+		handleError(response, err)
+		return
+	}
+	writeResponse(response, statsMap["/"])
+}
+
+// Handles non-kubernetes container stats requests to /stats/container/
+func (h *handler) handleSystemContainer(request *restful.Request, response *restful.Response) {
+	query, err := parseStatsRequest(request)
+	if err != nil {
+		handleError(response, err)
+		return
+	}
+
+	// Non-Kubernetes container stats.
+	containerName := path.Join("/", query.ContainerName)
+	stats, err := h.provider.GetRawContainerInfo(
+		containerName, query.cadvisorRequest(), query.Subcontainers)
+	if err != nil {
+		handleError(response, err)
+		return
+	}
+	writeResponse(response, stats)
+}
+
+// Handles kubernetes pod/container stats requests to:
+// /stats/<pod name>/<container name>
+// /stats/<namespace>/<pod name>/<uid>/<container name>
+func (h *handler) handlePodContainer(request *restful.Request, response *restful.Response) {
+	query, err := parseStatsRequest(request)
+	if err != nil {
+		handleError(response, err)
+		return
+	}
+
+	// Default parameters.
+	params := map[string]string{
+		"namespace": api.NamespaceDefault,
+		"uid":       "",
+	}
+	for k, v := range request.PathParameters() {
+		params[k] = v
+	}
+
+	if params["podName"] == "" || params["containerName"] == "" {
+		response.WriteErrorString(http.StatusBadRequest,
+			fmt.Sprintf("Invalid pod container request: %v", params))
+		return
+	}
+
+	pod, ok := h.provider.GetPodByName(params["namespace"], params["podName"])
+	if !ok {
+		glog.V(4).Infof("Container not found: %v", params)
+		handleError(response, kubecontainer.ErrContainerNotFound)
+		return
+	}
+	stats, err := h.provider.GetContainerInfo(
+		kubecontainer.GetPodFullName(pod),
+		types.UID(params["uid"]),
+		params["containerName"],
+		query.cadvisorRequest())
+
+	if err != nil {
+		handleError(response, err)
+		return
+	}
+	writeResponse(response, stats)
+}
+
+func writeResponse(response *restful.Response, stats interface{}) {
+	if stats == nil {
+		return
+	}
+	err := response.WriteAsJson(stats)
+	if err != nil {
+		handleError(response, err)
+	}
+}
+
+// handleError serializes an error object into an HTTP response.
+func handleError(response *restful.Response, err error) {
+	switch err {
+	case kubecontainer.ErrContainerNotFound:
+		response.WriteError(http.StatusNotFound, err)
+	default:
+		msg := fmt.Sprintf("Internal Error: %v", err)
+		glog.Infof("HTTP InternalServerError: %s", msg)
+		response.WriteErrorString(http.StatusNotFound, msg)
+	}
+}