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
+	})
+}