Prometheus metrics are encoded as text, not JSON (#1101)

Co-authored-by: Sanchit Mehta <sanchit.mehta602@gmail.com>

node/api/metrics_test.go

@@ -0,0 +1,149 @@
+// 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_test
+
+import (
+	"context"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/pkg/errors"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/virtual-kubelet/virtual-kubelet/node/api"
+	"google.golang.org/protobuf/proto"
+)
+
+const (
+	prometheusContentType = "text/plain; version=0.0.4"
+)
+
+func TestHandlePodMetricsResource(t *testing.T) {
+	testCases := []struct {
+		name               string
+		handler            api.PodMetricsResourceHandlerFunc
+		expectedStatusCode int
+		expectedError      error
+	}{
+		{
+			name: "Valid PodMetricsResourceHandlerFunc",
+			handler: func(_ context.Context) ([]*dto.MetricFamily, error) {
+				// Create the expected metrics.
+				cpuUsageMetric := &dto.MetricFamily{
+					Name:   proto.String("container_cpu_usage_seconds_total"),
+					Help:   proto.String("[ALPHA] Cumulative cpu time consumed by the container in core-seconds"),
+					Type:   dto.MetricType_GAUGE.Enum(),
+					Metric: []*dto.Metric{},
+				}
+				memoryUsageMetric := &dto.MetricFamily{
+					Name:   proto.String("container_memory_working_set_bytes"),
+					Help:   proto.String("[ALPHA] Current working set of the container in bytes"),
+					Type:   dto.MetricType_GAUGE.Enum(),
+					Metric: []*dto.Metric{},
+				}
+
+				// Add the sample metrics to the metric families.
+				cpuUsageMetric.Metric = append(cpuUsageMetric.Metric, createSampleMetric(
+					map[string]string{
+						"container": "simple-hello-world-container",
+						"namespace": "k8se-apps",
+						"pod":       "test-pod--zruwatj-86454fdc54-2wwpw",
+					},
+					0.1104636, 1680536423102,
+				))
+				cpuUsageMetric.Metric = append(cpuUsageMetric.Metric, createSampleMetric(
+					map[string]string{
+						"container": "simple-hello-world-container",
+						"namespace": "k8se-apps",
+						"pod":       "test-pod--zruwatj-86454fdc54-4mzd4",
+					},
+					0.11322, 1680536423103,
+				))
+				memoryUsageMetric.Metric = append(memoryUsageMetric.Metric, createSampleMetric(
+					map[string]string{
+						"container": "simple-hello-world-container",
+						"namespace": "k8se-apps",
+						"pod":       "test-pod--zruwatj-86454fdc54-2wwpw",
+					},
+					2.3277568e+07, 1680536423102,
+				))
+				memoryUsageMetric.Metric = append(memoryUsageMetric.Metric, createSampleMetric(
+					map[string]string{
+						"container": "simple-hello-world-container",
+						"namespace": "k8se-apps",
+						"pod":       "test-pod--zruwatj-86454fdc54-4mzd4",
+					},
+					2.2450176e+07, 1680536423104,
+				))
+
+				return []*dto.MetricFamily{cpuUsageMetric, memoryUsageMetric}, nil
+			},
+			expectedStatusCode: http.StatusOK,
+		},
+		{
+			name:               "Nil PodMetricsResourceHandlerFunc",
+			handler:            nil,
+			expectedStatusCode: http.StatusNotImplemented,
+		},
+		{
+			name: "Error in PodMetricsResourceHandlerFunc",
+			handler: func(_ context.Context) ([]*dto.MetricFamily, error) {
+				return nil, errors.New("test error")
+			},
+			expectedStatusCode: http.StatusInternalServerError,
+			expectedError:      errors.New("error getting status from provider: test error"),
+		},
+		// Add more test cases as needed
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			h := api.HandlePodMetricsResource(tc.handler)
+			require.NotNil(t, h)
+
+			rr := httptest.NewRecorder()
+			req, err := http.NewRequest("GET", "/metrics/resource", nil)
+			require.NoError(t, err)
+
+			h.ServeHTTP(rr, req)
+
+			assert.Equal(t, tc.expectedStatusCode, rr.Code)
+
+			if tc.expectedError != nil {
+				bodyBytes, err := ioutil.ReadAll(rr.Body)
+				require.NoError(t, err)
+				assert.Contains(t, string(bodyBytes), tc.expectedError.Error())
+			} else if tc.expectedStatusCode == http.StatusOK {
+				contentType := rr.Header().Get("Content-Type")
+				assert.Equal(t, prometheusContentType, contentType)
+			}
+		})
+	}
+}
+
+func createSampleMetric(labels map[string]string, value float64, timestamp int64) *dto.Metric {
+	labelPairs := []*dto.LabelPair{}
+	for k, v := range labels {
+		labelPairs = append(labelPairs, &dto.LabelPair{
+			Name:  proto.String(k),
+			Value: proto.String(v),
+		})
+	}
+
+	return &dto.Metric{Label: labelPairs, Gauge: &dto.Gauge{Value: &value}, TimestampMs: &timestamp}
+}