add the container_info{image="..."} metric

containers/container.go

@@ -32,6 +32,7 @@ type ContainerMetadata struct {
 	labels      map[string]string
 	volumes     map[string]string
 	logPath     string
+	image       string
 	logDecoder  logparser.Decoder
 	hostListens map[string][]netaddr.IPPort
 }
@@ -186,6 +187,10 @@ func (c *Container) Collect(ch chan<- prometheus.Metric) {
 	c.lock.RLock()
 	defer c.lock.RUnlock()
 
+	if c.metadata.image != "" {
+		ch <- gauge(metrics.ContainerInfo, 1, c.metadata.image)
+	}
+
 	ch <- counter(metrics.Restarts, float64(c.restarts))
 
 	if cpu, err := c.cgroup.CpuStat(); err == nil {

containers/containerd.go

@@ -56,6 +56,7 @@ func ContainerdInspect(containerID string) (*ContainerMetadata, error) {
 
 	res := &ContainerMetadata{
 		labels:  c.Labels,
+		image:   c.Image,
 		volumes: map[string]string{},
 	}
 

containers/dockerd.go

@@ -48,6 +48,7 @@ func DockerdInspect(containerID string) (*ContainerMetadata, error) {
 	res := &ContainerMetadata{
 		name:        strings.TrimPrefix(c.Name, "/"),
 		labels:      c.Config.Labels,
+		image:       c.Image,
 		volumes:     map[string]string{},
 		hostListens: map[string][]netaddr.IPPort{},
 	}

containers/metrics.go

@@ -6,7 +6,8 @@ import (
 )
 
 var metrics = struct {
-	Restarts *prometheus.Desc
+	ContainerInfo *prometheus.Desc
+	Restarts      *prometheus.Desc
 
 	CPULimit      *prometheus.Desc
 	CPUUsage      *prometheus.Desc
@@ -45,6 +46,8 @@ var metrics = struct {
 	JvmSafepointTime     *prometheus.Desc
 	JvmSafepointSyncTime *prometheus.Desc
 }{
+	ContainerInfo: metric("container_info", "Meta information about the container", "image"),
+
 	Restarts: metric("container_restarts_total", "Number of times the container was restarted"),
 
 	CPULimit:      metric("container_resources_cpu_limit_cores", "CPU limit of the container"),