discovery/kubernetes/kubernetes.go
func New(l log.Logger, conf *SDConfig) (*Discovery, error) {
	if l == nil {
		l = log.NewNopLogger()
	}
	var (
		kcfg *rest.Config
		err  error
	)
	if conf.APIServer.URL == nil {
		// Use the Kubernetes provided pod service account
		// as described in https://kubernetes.io/docs/admin/service-accounts-admin/
		kcfg, err = rest.InClusterConfig()
		if err != nil {
			return nil, err
		}
		level.Info(l).Log("msg", "Using pod service account via in-cluster config")
	} else {
		rt, err := config_util.NewRoundTripperFromConfig(conf.HTTPClientConfig, "kubernetes_sd")
		if err != nil {
			return nil, err
		}
		kcfg = &rest.Config{
			Host:      conf.APIServer.String(),
			Transport: rt,
		}
	}

	kcfg.UserAgent = "Prometheus/discovery"

	c, err := kubernetes.NewForConfig(kcfg)
	if err != nil {
		return nil, err
	}
	return &Discovery{
		client:             c,
		logger:             l,
		role:               conf.Role,
		namespaceDiscovery: &conf.NamespaceDiscovery,
		discoverers:        make([]discoverer, 0),
	}, nil
}
func New(l log.Logger, conf *SDConfig) (*Discovery, error) {
	if l == nil {
		l = log.NewNopLogger()
	}
	var (
		kcfg *rest.Config
		err  error
	)
	if conf.APIServer.URL == nil {
		// Use the Kubernetes provided pod service account
		// as described in https://kubernetes.io/docs/admin/service-accounts-admin/
		kcfg, err = rest.InClusterConfig()
		if err != nil {
			return nil, err
		}
		level.Info(l).Log("msg", "Using pod service account via in-cluster config")
	} else {
		rt, err := config_util.NewRoundTripperFromConfig(conf.HTTPClientConfig, "kubernetes_sd")
		if err != nil {
			return nil, err
		}
		kcfg = &rest.Config{
			Host:      conf.APIServer.String(),
			Transport: rt,
		}
	}

	kcfg.UserAgent = "Prometheus/discovery"

	c, err := kubernetes.NewForConfig(kcfg)
	if err != nil {
		return nil, err
	}
	return &Discovery{
		client:             c,
		logger:             l,
		role:               conf.Role,
		namespaceDiscovery: &conf.NamespaceDiscovery,
		discoverers:        make([]discoverer, 0),
	}, nil
}
// New creates a new Kubernetes discovery for the given role.