feat: Implement new metrics endpoint for k8s 1.24+ (#1082)

node/api/metrics.go

@@ -0,0 +1,53 @@
+// Copyright © 2017 The virtual-kubelet 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 api
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+
+	"github.com/pkg/errors"
+	dto "github.com/prometheus/client_model/go"
+)
+
+// PodMetricsResourceHandlerFunc defines the handler for getting pod metrics
+type PodMetricsResourceHandlerFunc func(context.Context) ([]*dto.MetricFamily, error)
+
+// HandlePodMetricsResource makes an HTTP handler for implementing the kubelet /metrics/resource endpoint
+func HandlePodMetricsResource(h PodMetricsResourceHandlerFunc) http.HandlerFunc {
+	if h == nil {
+		return NotImplemented
+	}
+	return handleError(func(w http.ResponseWriter, req *http.Request) error {
+		metrics, err := h(req.Context())
+		if err != nil {
+			if isCancelled(err) {
+				return err
+			}
+			return errors.Wrap(err, "error getting status from provider")
+		}
+
+		b, err := json.Marshal(metrics)
+		if err != nil {
+			return errors.Wrap(err, "error marshalling metrics")
+		}
+
+		if _, err := w.Write(b); err != nil {
+			return errors.Wrap(err, "could not write to client")
+		}
+		return nil
+	})
+}

node/api/server.go

@@ -41,10 +41,13 @@ type PodHandlerConfig struct { //nolint:golint
 	// GetPodsFromKubernetes is meant to enumerate the pods that the node is meant to be running
 	GetPodsFromKubernetes PodListerFunc
 	GetStatsSummary       PodStatsSummaryHandlerFunc
+	GetMetricsResource    PodMetricsResourceHandlerFunc
 	StreamIdleTimeout     time.Duration
 	StreamCreationTimeout time.Duration
 }
 
+const MetricsResourceRouteSuffix = "/metrics/resource"
+
 // PodHandler creates an http handler for interacting with pods/containers.
 func PodHandler(p PodHandlerConfig, debug bool) http.Handler {
 	r := mux.NewRouter()
@@ -72,6 +75,11 @@ func PodHandler(p PodHandlerConfig, debug bool) http.Handler {
 		r.HandleFunc("/stats/summary/", f).Methods("GET")
 	}
 
+	if p.GetMetricsResource != nil {
+		f := HandlePodMetricsResource(p.GetMetricsResource)
+		r.HandleFunc(MetricsResourceRouteSuffix, f).Methods("GET")
+		r.HandleFunc(MetricsResourceRouteSuffix+"/", f).Methods("GET")
+	}
 	r.NotFoundHandler = http.HandlerFunc(NotFound)
 	return r
 }
@@ -97,6 +105,26 @@ func PodStatsSummaryHandler(f PodStatsSummaryHandlerFunc) http.Handler {
 	return r
 }
 
+// PodMetricsResourceHandler creates an http handler for serving pod metrics.
+//
+// If the passed in handler func is nil this will create handlers which only
+// serves http.StatusNotImplemented
+func PodMetricsResourceHandler(f PodMetricsResourceHandlerFunc) http.Handler {
+	if f == nil {
+		return http.HandlerFunc(NotImplemented)
+	}
+
+	r := mux.NewRouter()
+
+	h := HandlePodMetricsResource(f)
+
+	r.Handle(MetricsResourceRouteSuffix, ochttp.WithRouteTag(h, "PodMetricsResourceHandler")).Methods("GET")
+	r.Handle(MetricsResourceRouteSuffix+"/", ochttp.WithRouteTag(h, "PodMetricsResourceHandler")).Methods("GET")
+
+	r.NotFoundHandler = http.HandlerFunc(NotFound)
+	return r
+}
+
 // AttachPodRoutes adds the http routes for pod stuff to the passed in serve mux.
 //
 // Callers should take care to namespace the serve mux as they see fit, however
@@ -111,7 +139,8 @@ func AttachPodRoutes(p PodHandlerConfig, mux ServeMux, debug bool) {
 // The main reason for this struct is in case of expansion we do not need to break
 // the package level API.
 type PodMetricsConfig struct {
-	GetStatsSummary PodStatsSummaryHandlerFunc
+	GetStatsSummary    PodStatsSummaryHandlerFunc
+	GetMetricsResource PodMetricsResourceHandlerFunc
 }
 
 // AttachPodMetricsRoutes adds the http routes for pod/node metrics to the passed in serve mux.
@@ -120,6 +149,7 @@ type PodMetricsConfig struct {
 // these routes get called by the Kubernetes API server.
 func AttachPodMetricsRoutes(p PodMetricsConfig, mux ServeMux) {
 	mux.Handle("/", InstrumentHandler(HandlePodStatsSummary(p.GetStatsSummary)))
+	mux.Handle("/", InstrumentHandler(HandlePodMetricsResource(p.GetMetricsResource)))
 }
 
 func instrumentRequest(r *http.Request) *http.Request {