ServiceMonitor Support PodTargetLabels/TargetLabels/JobLabel

[weenxin]

Background

Right now our ServiceMonitor don't support setting for PodTargetLabels field.

PodTargetLabels transfers labels on the Kubernetes Pod onto the target. It is very important for some usage like relabel.

Method to add this feature

Our Kmodules.xyz has AgentSpec definition

type PrometheusSpec struct {
	// Port number for the exporter side car.
	Port int32 `json:"port,omitempty"`

	// Namespace of Prometheus. Service monitors will be created in this namespace.
	Namespace string `json:"namespace,omitempty"`
	// Labels are key value pairs that is used to select Prometheus instance via ServiceMonitor labels.
	// +optional
	Labels map[string]string `json:"labels,omitempty"`

	// Interval at which metrics should be scraped
	Interval string `json:"interval,omitempty"`

	// Parameters are key value pairs that are passed as flags to exporters.
	// Parameters map[string]string `json:"parameters,omitempty"`
}

Prometheus' definition

type ServiceMonitorSpec struct {
	// The label to use to retrieve the job name from.
	JobLabel string `json:"jobLabel,omitempty"`
	// TargetLabels transfers labels on the Kubernetes Service onto the target.
	TargetLabels []string `json:"targetLabels,omitempty"`
	// PodTargetLabels transfers labels on the Kubernetes Pod onto the target.
	PodTargetLabels []string `json:"podTargetLabels,omitempty"`
	// A list of endpoints allowed as part of this ServiceMonitor.
	Endpoints []Endpoint `json:"endpoints"`
	// Selector to select Endpoints objects.
	Selector metav1.LabelSelector `json:"selector"`
	// Selector to select which namespaces the Endpoints objects are discovered from.
	NamespaceSelector NamespaceSelector `json:"namespaceSelector,omitempty"`
	// SampleLimit defines per-scrape limit on number of scraped samples that will be accepted.
	SampleLimit uint64 `json:"sampleLimit,omitempty"`
} 

We should support JobLabel , TargetLabels , PodTargetLabels , for usage.