Slightly improve UX around passing --metrics

daemon/cmd/daemon_main.go

@@ -686,7 +686,7 @@ func initializeFlags() {
 	flags.MarkHidden(option.MaxCtrlIntervalName)
 	option.BindEnv(Vp, option.MaxCtrlIntervalName)
 
-	flags.StringSlice(option.Metrics, []string{}, "Metrics that should be enabled or disabled from the default metric list. (+metric_foo to enable metric_foo , -metric_bar to disable metric_bar)")
+	flags.StringSlice(option.Metrics, []string{}, "Metrics that should be enabled or disabled from the default metric list. The list is expected to be separated by a space. (+metric_foo to enable metric_foo , -metric_bar to disable metric_bar)")
 	option.BindEnv(Vp, option.Metrics)
 
 	flags.Bool(option.EnableMonitorName, true, "Enable the monitor unix domain socket server")

install/kubernetes/cilium/README.md

@@ -499,7 +499,7 @@ contributors across the globe, there is almost always someone available to help.
 | preflight.validateCNPs | bool | `true` | By default we should always validate the installed CNPs before upgrading Cilium. This will make sure the user will have the policies deployed in the cluster with the right schema. |
 | priorityClassName | string | `""` | The priority class to use for cilium-agent. |
 | prometheus | object | `{"enabled":false,"metrics":null,"port":9962,"serviceMonitor":{"annotations":{},"enabled":false,"interval":"10s","labels":{},"metricRelabelings":null,"relabelings":[{"replacement":"${1}","sourceLabels":["__meta_kubernetes_pod_node_name"],"targetLabel":"node"}]}}` | Configure prometheus metrics on the configured port at /metrics |
-| prometheus.metrics | string | `nil` | Metrics that should be enabled or disabled from the default metric list. (+metric_foo to enable metric_foo , -metric_bar to disable metric_bar). ref: https://docs.cilium.io/en/stable/operations/metrics/#exported-metrics |
+| prometheus.metrics | string | `nil` | Metrics that should be enabled or disabled from the default metric list. The list is expected to be separated by a space. (+metric_foo to enable metric_foo , -metric_bar to disable metric_bar). ref: https://docs.cilium.io/en/stable/operations/metrics/#exported-metrics |
 | prometheus.serviceMonitor.annotations | object | `{}` | Annotations to add to ServiceMonitor cilium-agent |
 | prometheus.serviceMonitor.enabled | bool | `false` | Enable service monitors. This requires the prometheus CRDs to be available (see https://github.com/prometheus-operator/prometheus-operator/blob/master/example/prometheus-operator-crd/monitoring.coreos.com_servicemonitors.yaml) |
 | prometheus.serviceMonitor.interval | string | `"10s"` | Interval for scrape metrics. |

install/kubernetes/cilium/values.yaml

@@ -1586,9 +1586,9 @@ prometheus:
         replacement: ${1}
     # -- Metrics relabeling configs for the ServiceMonitor cilium-agent
     metricRelabelings: ~
-  # -- Metrics that should be enabled or disabled from the default metric
-  # list. (+metric_foo to enable metric_foo , -metric_bar to disable
-  # metric_bar).
+  # -- Metrics that should be enabled or disabled from the default metric list.
+  # The list is expected to be separated by a space. (+metric_foo to enable
+  # metric_foo , -metric_bar to disable metric_bar).
   # ref: https://docs.cilium.io/en/stable/operations/metrics/#exported-metrics
   metrics: ~
 

install/kubernetes/cilium/values.yaml.tmpl

@@ -1583,9 +1583,9 @@ prometheus:
         replacement: ${1}
     # -- Metrics relabeling configs for the ServiceMonitor cilium-agent
     metricRelabelings: ~
-  # -- Metrics that should be enabled or disabled from the default metric
-  # list. (+metric_foo to enable metric_foo , -metric_bar to disable
-  # metric_bar).
+  # -- Metrics that should be enabled or disabled from the default metric list.
+  # The list is expected to be separated by a space. (+metric_foo to enable
+  # metric_foo , -metric_bar to disable metric_bar).
   # ref: https://docs.cilium.io/en/stable/operations/metrics/#exported-metrics
   metrics: ~
 

pkg/metrics/metrics.go

@@ -679,6 +679,9 @@ func CreateConfiguration(metricsEnabled []string) (Configuration, []prometheus.C
 
 	for _, metricName := range metricsEnabled {
 		switch metricName {
+		default:
+			logrus.WithField("metric", metricName).Warning("Metric does not exist, skipping")
+
 		case Namespace + "_" + SubsystemAgent + "_api_process_time_seconds":
 			APIInteractions = prometheus.NewHistogramVec(prometheus.HistogramOpts{
 				Namespace: Namespace,