telmetry: add databroker storage metrics and tracing (#1161)

* telmetry: add databroker storage metrics and tracing

internal/telemetry/metrics/kv_test.go

@@ -0,0 +1,34 @@
+package metrics
+
+import (
+	"testing"
+
+	"github.com/gomodule/redigo/redis"
+	"go.opencensus.io/metric/metricdata"
+)
+
+func Test_AddRedisMetrics(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		stat redis.PoolStats
+		want int64
+	}{
+		{"redis_conns", redis.PoolStats{ActiveCount: 7}, 7},
+		{"redis_idle_conns", redis.PoolStats{IdleCount: 3}, 3},
+		{"redis_wait_count_total", redis.PoolStats{WaitCount: 2}, 2},
+	}
+
+	labelValues := []metricdata.LabelValue{
+		metricdata.NewLabelValue("redis"),
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			AddRedisMetrics(func() redis.PoolStats { return tt.stat })
+			testMetricRetrieval(registry.registry.Read(), t, labelValues, tt.want, tt.name)
+		})
+	}
+
+}