feat: add current pids metrics

Author: davidborzek

internal/collector/collector.go

@@ -110,6 +110,7 @@ func (c *DockerCollector) collectContainerMetrics(ctx context.Context, container
 	c.memoryMetrics(ch, name, stats)
 	c.networkMetrics(ch, name, stats)
 	c.blockIOMetrics(ch, name, stats)
+	c.pidsMetrics(ch, name, stats)
 }
 
 func (c *DockerCollector) cpuMetrics(ch chan<- prometheus.Metric, name string, stats *types.StatsJSON) {
@@ -240,6 +241,14 @@ func (c *DockerCollector) blockIOMetrics(ch chan<- prometheus.Metric, name strin
 	)
 }
 
+func (c *DockerCollector) pidsMetrics(ch chan<- prometheus.Metric, name string, stats *types.StatsJSON) {
+	ch <- prometheus.MustNewConstMetric(pidsCurrent,
+		prometheus.GaugeValue,
+		float64(stats.PidsStats.Current),
+		name,
+	)
+}
+
 // containerStats gets the stats of a single containers.
 func (c *DockerCollector) containerStats(ctx context.Context, containerID string) (*types.StatsJSON, error) {
 	r, err := c.client.ContainerStats(ctx, containerID, false)

internal/collector/collector_test.go

@@ -90,6 +90,9 @@ func TestCollectMetrics(t *testing.T) {
 	# HELP docker_container_network_tx_packets Network sent packets total
 	# TYPE docker_container_network_tx_packets gauge
 	docker_container_network_tx_packets{name="testName",network="eth0"} 864
+	# HELP docker_container_pids_current Current number of pids
+	# TYPE docker_container_pids_current gauge
+	docker_container_pids_current{name="testName"} 12
 	# HELP docker_container_state State of the container
 	# TYPE docker_container_state gauge
 	docker_container_state{name="testName",state="running"} 1
@@ -165,6 +168,9 @@ func buildStatsResponse() types.StatsJSON {
 				SystemUsage: 1223,
 				OnlineCPUs:  4,
 			},
+			PidsStats: types.PidsStats{
+				Current: 12,
+			},
 		},
 		Networks: map[string]types.NetworkStats{
 			"eth0": {

internal/collector/metrics.go

@@ -137,4 +137,15 @@ var (
 		[]string{"name"},
 		nil,
 	)
+
+	/*
+		PIDs Metrics
+	*/
+
+	pidsCurrent = prometheus.NewDesc(
+		"docker_container_pids_current",
+		"Current number of pids",
+		[]string{"name"},
+		nil,
+	)
 )