Support List with options for custom metrics label selector

pkg/apiserver/endpoints/handlers/get.go

@@ -0,0 +1,213 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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 handlers
+
+import (
+	"context"
+	"fmt"
+	"math/rand"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/golang/glog"
+
+	"k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/api/meta"
+	metainternalversion "k8s.io/apimachinery/pkg/apis/meta/internalversion"
+	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apiserver/pkg/endpoints/handlers"
+	"k8s.io/apiserver/pkg/endpoints/metrics"
+	"k8s.io/apiserver/pkg/endpoints/request"
+	"k8s.io/apiserver/pkg/registry/rest"
+	utiltrace "k8s.io/utils/trace"
+
+	cm_rest "github.com/kubernetes-incubator/custom-metrics-apiserver/pkg/apiserver/registry/rest"
+)
+
+func ListResourceWithOptions(r cm_rest.ListerWithOptions, rw rest.Watcher, scope handlers.RequestScope, forceWatch bool, minRequestTimeout time.Duration) http.HandlerFunc {
+	list := func(w http.ResponseWriter, req *http.Request, ctx context.Context, opts *metainternalversion.ListOptions) (runtime.Object, error) {
+		extraOpts, subpath, subpathKey := r.NewListOptions()
+		if err := getRequestOptions(req, scope, extraOpts, subpath, subpathKey, false); err != nil {
+			err = errors.NewBadRequest(err.Error())
+			return nil, err
+		}
+		return r.List(ctx, opts, extraOpts)
+	}
+	return listResource(list, rw, scope, forceWatch, minRequestTimeout)
+}
+
+// getRequestOptions parses out options and can include path information.  The path information shouldn't include the subresource.
+func getRequestOptions(req *http.Request, scope handlers.RequestScope, into runtime.Object, subpath bool, subpathKey string, isSubresource bool) error {
+	if into == nil {
+		return nil
+	}
+
+	query := req.URL.Query()
+	if subpath {
+		newQuery := make(url.Values)
+		for k, v := range query {
+			newQuery[k] = v
+		}
+
+		ctx := req.Context()
+		requestInfo, _ := request.RequestInfoFrom(ctx)
+		startingIndex := 2
+		if isSubresource {
+			startingIndex = 3
+		}
+
+		p := strings.Join(requestInfo.Parts[startingIndex:], "/")
+
+		// ensure non-empty subpaths correctly reflect a leading slash
+		if len(p) > 0 && !strings.HasPrefix(p, "/") {
+			p = "/" + p
+		}
+
+		// ensure subpaths correctly reflect the presence of a trailing slash on the original request
+		if strings.HasSuffix(requestInfo.Path, "/") && !strings.HasSuffix(p, "/") {
+			p += "/"
+		}
+
+		newQuery[subpathKey] = []string{p}
+		query = newQuery
+	}
+	return scope.ParameterCodec.DecodeParameters(query, scope.Kind.GroupVersion(), into)
+}
+
+func listResource(list func(http.ResponseWriter, *http.Request, context.Context, *metainternalversion.ListOptions) (runtime.Object, error), rw rest.Watcher, scope handlers.RequestScope, forceWatch bool, minRequestTimeout time.Duration) http.HandlerFunc {
+	return func(w http.ResponseWriter, req *http.Request) {
+		// For performance tracking purposes.
+		trace := utiltrace.New("List " + req.URL.Path)
+
+		namespace, err := scope.Namer.Namespace(req)
+		if err != nil {
+			writeError(&scope, err, w, req)
+			return
+		}
+
+		// Watches for single objects are routed to this function.
+		// Treat a name parameter the same as a field selector entry.
+		hasName := true
+		_, name, err := scope.Namer.Name(req)
+		if err != nil {
+			hasName = false
+		}
+
+		ctx := req.Context()
+		ctx = request.WithNamespace(ctx, namespace)
+
+		opts := metainternalversion.ListOptions{}
+		if err := metainternalversion.ParameterCodec.DecodeParameters(req.URL.Query(), scope.MetaGroupVersion, &opts); err != nil {
+			err = errors.NewBadRequest(err.Error())
+			writeError(&scope, err, w, req)
+			return
+		}
+
+		// transform fields
+		// TODO: DecodeParametersInto should do this.
+		if opts.FieldSelector != nil {
+			fn := func(label, value string) (newLabel, newValue string, err error) {
+				return scope.Convertor.ConvertFieldLabel(scope.Kind, label, value)
+			}
+			if opts.FieldSelector, err = opts.FieldSelector.Transform(fn); err != nil {
+				// TODO: allow bad request to set field causes based on query parameters
+				err = errors.NewBadRequest(err.Error())
+				writeError(&scope, err, w, req)
+				return
+			}
+		}
+
+		if hasName {
+			// metadata.name is the canonical internal name.
+			// SelectionPredicate will notice that this is a request for
+			// a single object and optimize the storage query accordingly.
+			nameSelector := fields.OneTermEqualSelector("metadata.name", name)
+
+			// Note that fieldSelector setting explicitly the "metadata.name"
+			// will result in reaching this branch (as the value of that field
+			// is propagated to requestInfo as the name parameter.
+			// That said, the allowed field selectors in this branch are:
+			// nil, fields.Everything and field selector matching metadata.name
+			// for our name.
+			if opts.FieldSelector != nil && !opts.FieldSelector.Empty() {
+				selectedName, ok := opts.FieldSelector.RequiresExactMatch("metadata.name")
+				if !ok || name != selectedName {
+					writeError(&scope, errors.NewBadRequest("fieldSelector metadata.name doesn't match requested name"), w, req)
+					return
+				}
+			} else {
+				opts.FieldSelector = nameSelector
+			}
+		}
+
+		if opts.Watch || forceWatch {
+			if rw == nil {
+				writeError(&scope, errors.NewMethodNotSupported(scope.Resource.GroupResource(), "watch"), w, req)
+				return
+			}
+			// TODO: Currently we explicitly ignore ?timeout= and use only ?timeoutSeconds=.
+			timeout := time.Duration(0)
+			if opts.TimeoutSeconds != nil {
+				timeout = time.Duration(*opts.TimeoutSeconds) * time.Second
+			}
+			if timeout == 0 && minRequestTimeout > 0 {
+				timeout = time.Duration(float64(minRequestTimeout) * (rand.Float64() + 1.0))
+			}
+			glog.V(3).Infof("Starting watch for %s, rv=%s labels=%s fields=%s timeout=%s", req.URL.Path, opts.ResourceVersion, opts.LabelSelector, opts.FieldSelector, timeout)
+
+			watcher, err := rw.Watch(ctx, &opts)
+			if err != nil {
+				writeError(&scope, err, w, req)
+				return
+			}
+			requestInfo, _ := request.RequestInfoFrom(ctx)
+			metrics.RecordLongRunning(req, requestInfo, func() {
+				serveWatch(watcher, scope, req, w, timeout)
+			})
+			return
+		}
+
+		// Log only long List requests (ignore Watch).
+		defer trace.LogIfLong(500 * time.Millisecond)
+		trace.Step("About to List from storage")
+		result, err := list(w, req, ctx, &opts)
+		if err != nil {
+			writeError(&scope, err, w, req)
+			return
+		}
+		trace.Step("Listing from storage done")
+		numberOfItems, err := setListSelfLink(result, ctx, req, scope.Namer)
+		if err != nil {
+			writeError(&scope, err, w, req)
+			return
+		}
+		trace.Step("Self-linking done")
+		// Ensure empty lists return a non-nil items slice
+		if numberOfItems == 0 && meta.IsListType(result) {
+			if err := meta.SetList(result, []runtime.Object{}); err != nil {
+				writeError(&scope, err, w, req)
+				return
+			}
+		}
+
+		transformResponseObject(ctx, scope, req, w, http.StatusOK, result)
+		trace.Step(fmt.Sprintf("Writing http response done (%d items)", numberOfItems))
+	}
+}