var (
	// HTTPRequests tracks the number of the http requests received since the server started.
	HTTPRequests = metrics.NewCounterVec(
		&metrics.CounterOpts{
			Subsystem:      kubeletSubsystem,
			Name:           "http_requests_total",
			Help:           "Number of the http requests received since the server started",
			StabilityLevel: metrics.ALPHA,
		},

		[]string{"method", "path", "server_type", "long_running"},
	)
	// HTTPRequestsDuration tracks the duration in seconds to serve http requests.
	HTTPRequestsDuration = metrics.NewHistogramVec(
		&metrics.HistogramOpts{
			Subsystem: kubeletSubsystem,
			Name:      "http_requests_duration_seconds",
			Help:      "Duration in seconds to serve http requests",

			Buckets:        metrics.DefBuckets,
			StabilityLevel: metrics.ALPHA,
		},
		[]string{"method", "path", "server_type", "long_running"},
	)
	// HTTPInflightRequests tracks the number of the inflight http requests.
	HTTPInflightRequests = metrics.NewGaugeVec(
		&metrics.GaugeOpts{
			Subsystem:      kubeletSubsystem,
			Name:           "http_inflight_requests",
			Help:           "Number of the inflight http requests",
			StabilityLevel: metrics.ALPHA,
		},
		[]string{"method", "path", "server_type", "long_running"},
	)
	// VolumeStatCalDuration tracks the duration in seconds to calculate volume stats.
	// this metric is mainly for comparison between fsquota monitoring and `du` for disk usage.
	VolumeStatCalDuration = metrics.NewHistogramVec(
		&metrics.HistogramOpts{
			Subsystem:      kubeletSubsystem,
			Name:           "volume_metric_collection_duration_seconds",
			Help:           "Duration in seconds to calculate volume stats",
			Buckets:        metrics.DefBuckets,
			StabilityLevel: metrics.ALPHA,
		},
		[]string{"metric_source"},
	)
	MetricsProvider = metrics.NewGaugeVec(
		&metrics.GaugeOpts{
			Subsystem:      kubeletSubsystem,
			Name:           "metrics_provider",
			Help:           "Metrics provider used by kubelet to collect container stats. Values can be 'cadvisor' and 'cri'",
			StabilityLevel: metrics.ALPHA,
		},
		[]string{"provider"},
	)
	// WebSocketStreamingRequests counts WebSocket streaming requests received by the kubelet,
	// labeled by subresource.
	WebSocketStreamingRequests = metrics.NewCounterVec(
		&metrics.CounterOpts{
			Subsystem:      kubeletSubsystem,
			Name:           "websocket_streaming_requests_total",
			Help:           "Total number of WebSocket streaming requests (exec/attach/portforward) received by the kubelet.",
			StabilityLevel: metrics.ALPHA,
		},
		[]string{"subresource"},
	)
)

type MetricsProviderType string

const (
	CAdvisorMetricsProvider MetricsProviderType = "cadvisor"
	CRIMetricsProvider      MetricsProviderType = "cri"
)