func ExampleCounter() {
	pushCounter := prometheus.NewCounter(prometheus.CounterOpts{
		Name: "repository_pushes", // Note: No help string...
	})
	err := prometheus.Register(pushCounter) // ... so this will return an error.
	if err != nil {
		fmt.Println("Push counter couldn't be registered, no counting will happen:", err)
		return
	}

	// Try it once more, this time with a help string.
	pushCounter = prometheus.NewCounter(prometheus.CounterOpts{
		Name: "repository_pushes",
		Help: "Number of pushes to external repository.",
	})
	err = prometheus.Register(pushCounter)
	if err != nil {
		fmt.Println("Push counter couldn't be registered AGAIN, no counting will happen:", err)
		return
	}

	pushComplete := make(chan struct{})
	// TODO: Start a goroutine that performs repository pushes and reports
	// each completion via the channel.
	for _ = range pushComplete {
		pushCounter.Inc()
	}
	// Output:
	// Push counter couldn't be registered, no counting will happen: descriptor Desc{fqName: "repository_pushes", help: "", constLabels: {}, variableLabels: []} is invalid: empty help string
}

func newMetrics(r prometheus.Registerer) *metrics {
	m := &metrics{}

	m.gcDuration = prometheus.NewSummary(prometheus.SummaryOpts{
		Name: "alertmanager_nflog_gc_duration_seconds",
		Help: "Duration of the last notification log garbage collection cycle.",
	})
	m.snapshotDuration = prometheus.NewSummary(prometheus.SummaryOpts{
		Name: "alertmanager_nflog_snapshot_duration_seconds",
		Help: "Duration of the last notification log snapshot.",
	})
	m.queriesTotal = prometheus.NewCounter(prometheus.CounterOpts{
		Name: "alertmanager_nflog_queries_total",
		Help: "Number of notification log queries were received.",
	})
	m.queryErrorsTotal = prometheus.NewCounter(prometheus.CounterOpts{
		Name: "alertmanager_nflog_query_errors_total",
		Help: "Number notification log received queries that failed.",
	})
	m.queryDuration = prometheus.NewHistogram(prometheus.HistogramOpts{
		Name: "alertmanager_nflog_query_duration_seconds",
		Help: "Duration of notification log query evaluation.",
	})

	if r != nil {
		r.MustRegister(
			m.gcDuration,
			m.snapshotDuration,
			m.queriesTotal,
			m.queryErrorsTotal,
			m.queryDuration,
		)
	}
	return m
}

func initPrometheusMetrics() {
	TotalClientCounter = stat.NewGauge(stat.GaugeOpts{
		Name: "total_clients",
		Help: "Total number of connected clients",
	})

	TotalNodes = stat.NewGauge(stat.GaugeOpts{
		Name: "meshnodes_total",
		Help: "Total number of Nodes",
	})

	TotalNodeTrafficRx = stat.NewCounter(stat.CounterOpts{
		Name: "total_traffic_rx",
		Help: "Total accumulated received traffic as reported by Nodes",
	})

	TotalNodeTrafficTx = stat.NewCounter(stat.CounterOpts{
		Name: "total_traffic_tx",
		Help: "Total accumulated transmitted traffic as reported by Nodes",
	})

	TotalNodeMgmtTrafficRx = stat.NewCounter(stat.CounterOpts{
		Name: "total_traffic_mgmt_rx",
		Help: "Total accumulated received management traffic as reported by Nodes",
	})

	TotalNodeMgmtTrafficTx = stat.NewCounter(stat.CounterOpts{
		Name: "total_traffic_mgmt_tx",
		Help: "Total accumulated transmitted management traffic as reported by Nodes",
	})

	OnlineNodes = stat.NewGauge(stat.GaugeOpts{
		Name: "meshnodes_online_total",
		Help: "All online nodes",
	})

	NodesTrafficRx = stat.NewCounterVec(stat.CounterOpts{
		Name: "meshnode_traffic_rx",
		Help: "Transmitted traffic from nodes",
	}, append(nodeLabels, "type"))

	NodesTrafficTx = stat.NewCounterVec(stat.CounterOpts{
		Name: "meshnode_traffic_tx",
		Help: "Received traffic on nodes",
	}, append(nodeLabels, "type"))

	NodesUptime = stat.NewCounterVec(stat.CounterOpts{
		Name: "meshnode_uptime",
		Help: "Uptime of meshnodes",
	}, nodeLabels)

	NodesClients = stat.NewGaugeVec(stat.GaugeOpts{
		Name: "meshnode_clients",
		Help: "Clients on single meshnodes",
	}, nodeLabels)
}

// NewExporter returns an initialized Exporter.
func NewExporter(apiKey, serverType string, hostURL *url.URL) *Exporter {
	var gaugeDefs []gaugeDefinition
	var counterVecDefs []counterVecDefinition

	gaugeMetrics := make(map[int]prometheus.Gauge)
	counterVecMetrics := make(map[int]*prometheus.CounterVec)

	switch serverType {
	case "recursor":
		gaugeDefs = recursorGaugeDefs
		counterVecDefs = recursorCounterVecDefs
	case "authoritative":
		gaugeDefs = authoritativeGaugeDefs
		counterVecDefs = authoritativeCounterVecDefs
	case "dnsdist":
		gaugeDefs = dnsdistGaugeDefs
		counterVecDefs = dnsdistCounterVecDefs
	}

	for _, def := range gaugeDefs {
		gaugeMetrics[def.id] = newGaugeMetric(serverType, def.name, def.desc)
	}

	for _, def := range counterVecDefs {
		counterVecMetrics[def.id] = newCounterVecMetric(serverType, def.name, def.desc, []string{def.label})
	}

	return &Exporter{
		HostURL:    hostURL,
		ServerType: serverType,
		ApiKey:     apiKey,
		up: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Subsystem: serverType,
			Name:      "up",
			Help:      "Was the last scrape of PowerDNS successful.",
		}),
		totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: serverType,
			Name:      "exporter_total_scrapes",
			Help:      "Current total PowerDNS scrapes.",
		}),
		jsonParseFailures: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: serverType,
			Name:      "exporter_json_parse_failures",
			Help:      "Number of errors while parsing PowerDNS JSON stats.",
		}),
		gaugeMetrics:      gaugeMetrics,
		counterVecMetrics: counterVecMetrics,
		gaugeDefs:         gaugeDefs,
		counterVecDefs:    counterVecDefs,
	}
}

// NewHandler constructs a new Handler.
func New(o *HandlerOptions) *Handler {
	ctx, cancel := context.WithCancel(context.Background())

	return &Handler{
		queue:  make(model.Alerts, 0, o.QueueCapacity),
		ctx:    ctx,
		cancel: cancel,
		more:   make(chan struct{}, 1),
		opts:   o,

		latency: prometheus.NewSummary(prometheus.SummaryOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "latency_seconds",
			Help:      "Latency quantiles for sending alert notifications (not including dropped notifications).",
		}),
		errors: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "errors_total",
			Help:      "Total number of errors sending alert notifications.",
		}),
		sent: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "sent_total",
			Help:      "Total number of alerts successfully sent.",
		}),
		dropped: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "dropped_total",
			Help:      "Total number of alerts dropped due to alert manager missing in configuration.",
		}),
		queueLength: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "queue_length",
			Help:      "The number of alert notifications in the queue.",
		}),
		queueCapacity: prometheus.MustNewConstMetric(
			prometheus.NewDesc(
				prometheus.BuildFQName(namespace, subsystem, "queue_capacity"),
				"The capacity of the alert notifications queue.",
				nil, nil,
			),
			prometheus.GaugeValue,
			float64(o.QueueCapacity),
		),
	}
}

// NewExporter returns a new MySQL exporter for the provided DSN.
func NewExporter(dsn string) *Exporter {
	return &Exporter{
		dsn: dsn,
		duration: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Subsystem: exporter,
			Name:      "last_scrape_duration_seconds",
			Help:      "Duration of the last scrape of metrics from MySQL.",
		}),
		totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: exporter,
			Name:      "scrapes_total",
			Help:      "Total number of times MySQL was scraped for metrics.",
		}),
		scrapeErrors: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: exporter,
			Name:      "scrape_errors_total",
			Help:      "Total number of times an error occurred scraping a MySQL.",
		}, []string{"collector"}),
		error: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Subsystem: exporter,
			Name:      "last_scrape_error",
			Help:      "Whether the last scrape of metrics from MySQL resulted in an error (1 for error, 0 for success).",
		}),
		mysqldUp: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "up",
			Help:      "Whether the MySQL server is up.",
		}),
	}
}

func NewRedisExporter(addrs []string, namespace string) *Exporter {
	e := Exporter{
		addrs:     addrs,
		namespace: namespace,

		duration: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "exporter_last_scrape_duration_seconds",
			Help:      "The last scrape duration.",
		}),
		totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Name:      "exporter_scrapes_total",
			Help:      "Current total redis scrapes.",
		}),
		scrapeErrors: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "exporter_last_scrape_error",
			Help:      "The last scrape error status.",
		}),
	}

	e.initGauges()
	return &e
}

func NewPostgreSQLExporter(dsn string, cq []metrics.CustomQuery) *Exporter {
	e := &Exporter{
		dsn: dsn,
		metrics: []metrics.Collection{
			metrics.NewBufferMetrics(),
			metrics.NewDBMetrics(strings.Split(*databases, ",")),
			metrics.NewSlowQueryMetrics(*slow),
			metrics.NewCustomQueryMetrics(cq),
		},
		totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Name:      "exporter_scrapes_total",
			Help:      "Current total postgresql scrapes.",
		}),
		duration: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "exporter_last_scrape_duration_seconds",
			Help:      "The last scrape duration.",
		}),
		errors: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "exporter_last_scrape_error",
			Help:      "The last scrape error status.",
		}),
	}

	if len(*tables) > 0 {
		e.metrics = append(e.metrics, metrics.NewTableMetrics(strings.Split(*tables, ",")))
	}

	return e
}

// NewExporter returns an initialized Exporter.
func NewExporter(uri string) *Exporter {
	return &Exporter{
		URI: uri,
		scrapeFailures: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Name:      "exporter_scrape_failures_total",
			Help:      "Number of errors while scraping nginx.",
		}),
		processedConnections: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: namespace,
			Name:      "connections_processed_total",
			Help:      "Number of connections processed by nginx",
		},
			[]string{"stage"},
		),
		currentConnections: prometheus.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "connections_current",
			Help:      "Number of connections currently processed by nginx",
		},
			[]string{"state"},
		),
		client: &http.Client{
			Transport: &http.Transport{
				TLSClientConfig: &tls.Config{InsecureSkipVerify: *insecure},
			},
		},
	}
}

// NewExporter returns a new PostgreSQL exporter for the provided DSN.
func NewExporter(dsn string, userQueriesPath string) *Exporter {
	return &Exporter{
		dsn:             dsn,
		userQueriesPath: userQueriesPath,
		duration: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Subsystem: exporter,
			Name:      "last_scrape_duration_seconds",
			Help:      "Duration of the last scrape of metrics from PostgresSQL.",
		}),
		totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: exporter,
			Name:      "scrapes_total",
			Help:      "Total number of times PostgresSQL was scraped for metrics.",
		}),
		error: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Subsystem: exporter,
			Name:      "last_scrape_error",
			Help:      "Whether the last scrape of metrics from PostgreSQL resulted in an error (1 for error, 0 for success).",
		}),
		variableMap:    nil,
		metricMap:      nil,
		queryOverrides: nil,
	}
}

func NewRethinkDBExporter(addr, auth, clusterName, namespace string) *Exporter {
	return &Exporter{
		addrs:       strings.Split(addr, ","),
		auth:        auth,
		clusterName: clusterName,
		namespace:   namespace,

		duration: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "exporter_last_scrape_duration_seconds",
			Help:      "The last scrape duration.",
		}),
		totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Name:      "exporter_scrapes_total",
			Help:      "Current total rethinkdb scrapes.",
		}),
		scrapeError: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "exporter_last_scrape_error",
			Help:      "The last scrape error status.",
		}),
		metrics: map[string]*prometheus.GaugeVec{},
	}
}

// Add prometheus logging to SkyDNS
func init() {
	server.StatsForwardCount = newCounter(prometheus.NewCounter(prometheus.CounterOpts{
		Name: "dns_forward_count",
		Help: "Counter of DNS requests forwarded",
	}))
	server.StatsLookupCount = newCounter(prometheus.NewCounter(prometheus.CounterOpts{
		Name: "dns_lookup_count",
		Help: "Counter of DNS lookups performed",
	}))
	server.StatsRequestCount = newCounter(prometheus.NewCounter(prometheus.CounterOpts{
		Name: "dns_request_count",
		Help: "Counter of DNS requests made",
	}))
	server.StatsDnssecOkCount = newCounter(prometheus.NewCounter(prometheus.CounterOpts{
		Name: "dns_dnssec_ok_count",
		Help: "Counter of DNSSEC requests that were valid",
	}))
	server.StatsDnssecCacheMiss = newCounter(prometheus.NewCounter(prometheus.CounterOpts{
		Name: "dns_dnssec_cache_miss_count",
		Help: "Counter of DNSSEC requests that missed the cache",
	}))
	server.StatsNameErrorCount = newCounter(prometheus.NewCounter(prometheus.CounterOpts{
		Name: "dns_name_error_count",
		Help: "Counter of DNS requests resulting in a name error",
	}))
	server.StatsNoDataCount = newCounter(prometheus.NewCounter(prometheus.CounterOpts{
		Name: "dns_no_data_count",
		Help: "Counter of DNS requests that contained no data",
	}))
}

// NewExporter returns an initialized exporter
func NewExporter(server string) *Exporter {
	return &Exporter{
		mc: memcache.New(server),
		up: prometheus.NewGauge(
			prometheus.GaugeOpts{
				Name:        "up",
				Namespace:   namespace,
				Help:        "Are the servers up.",
				ConstLabels: prometheus.Labels{"server": server},
			},
		),
		uptime: prometheus.NewCounter(
			prometheus.CounterOpts{
				Name:        "uptime",
				Namespace:   namespace,
				Help:        "The uptime of the server.",
				ConstLabels: prometheus.Labels{"server": server},
			},
		),
		cache: prometheus.NewCounterVec(
			prometheus.CounterOpts{
				Name:        "cache",
				Namespace:   namespace,
				Help:        "The cache hits/misses broken down by command (get, set, etc.).",
				ConstLabels: prometheus.Labels{"server": server},
			},
			[]string{"command", "status"},
		),
		usage: prometheus.NewGaugeVec(
			prometheus.GaugeOpts{
				Name:        "usage",
				Namespace:   namespace,
				Help:        "Details the resource usage (items/connections) of the server, by time (current/total).",
				ConstLabels: prometheus.Labels{"server": server},
			},
			[]string{"time", "resource"},
		),
		bytes: prometheus.NewCounterVec(
			prometheus.CounterOpts{
				Name:        "bytes",
				Namespace:   namespace,
				Help:        "The bytes sent/received by the server.",
				ConstLabels: prometheus.Labels{"server": server},
			},
			[]string{"direction"},
		),
		removals: prometheus.NewCounterVec(
			prometheus.CounterOpts{
				Name:        "removal",
				Namespace:   namespace,
				Help:        "Number of items that have been evicted/expired (status), and if the were fetched ever or not.",
				ConstLabels: prometheus.Labels{"server": server},
			},
			[]string{"status", "fetched"},
		),
	}
}

func (_ prometheusMetricsProvider) NewAddsMetric(name string) workqueue.CounterMetric {
	adds := prometheus.NewCounter(prometheus.CounterOpts{
		Subsystem: name,
		Name:      "adds",
		Help:      "Total number of adds handled by workqueue: " + name,
	})
	prometheus.Register(adds)
	return adds
}

func (_ prometheusMetricsProvider) NewRetriesMetric(name string) workqueue.CounterMetric {
	retries := prometheus.NewCounter(prometheus.CounterOpts{
		Subsystem: name,
		Name:      "retries",
		Help:      "Total number of retries handled by workqueue: " + name,
	})
	prometheus.Register(retries)
	return retries
}

// Takes a prometheus registry and returns a new Collector exposing
// the current system time in seconds since epoch.
func NewTimeCollector() (Collector, error) {
	return &timeCollector{
		metric: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: Namespace,
			Name:      "time",
			Help:      "System time in seconds since epoch (1970).",
		}),
	}, nil
}

// NewSensors creates new sensors from a raw config
func NewSensors(raw []interface{}) ([]*Sensor, error) {
	var sensors []*Sensor
	if err := utils.DecodeRaw(raw, &sensors); err != nil {
		return nil, fmt.Errorf("Sensor configuration error: %v", err)
	}
	for _, s := range sensors {
		check, err := commands.NewCommand(s.CheckExec, s.Timeout)
		if err != nil {
			return nil, fmt.Errorf("could not parse check in sensor %s: %s", s.Name, err)
		}
		check.Name = fmt.Sprintf("%s.sensor", s.Name)
		s.checkCmd = check

		// the prometheus client lib's API here is baffling... they don't expose
		// an interface or embed their Opts type in each of the Opts "subtypes",
		// so we can't share the initialization.
		switch {
		case s.Type == "counter":
			s.collector = prometheus.NewCounter(prometheus.CounterOpts{
				Namespace: s.Namespace,
				Subsystem: s.Subsystem,
				Name:      s.Name,
				Help:      s.Help,
			})
		case s.Type == "gauge":
			s.collector = prometheus.NewGauge(prometheus.GaugeOpts{
				Namespace: s.Namespace,
				Subsystem: s.Subsystem,
				Name:      s.Name,
				Help:      s.Help,
			})
		case s.Type == "histogram":
			s.collector = prometheus.NewHistogram(prometheus.HistogramOpts{
				Namespace: s.Namespace,
				Subsystem: s.Subsystem,
				Name:      s.Name,
				Help:      s.Help,
			})
		case s.Type == "summary":
			s.collector = prometheus.NewSummary(prometheus.SummaryOpts{
				Namespace: s.Namespace,
				Subsystem: s.Subsystem,
				Name:      s.Name,
				Help:      s.Help,
			})
		default:
			return nil, fmt.Errorf("invalid sensor type: %s", s.Type)
		}
		// we're going to unregister before every attempt to register
		// so that we can reload config
		prometheus.Unregister(s.collector)
		if err := prometheus.Register(s.collector); err != nil {
			return nil, err
		}
	}
	return sensors, nil
}

func NewExporter(uri string) *Exporter {
	return &Exporter{
		URI: uri,
		up: prometheus.NewDesc(
			prometheus.BuildFQName(namespace, "", "up"),
			"Could the apache server be reached",
			nil,
			nil),
		scrapeFailures: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Name:      "exporter_scrape_failures_total",
			Help:      "Number of errors while scraping apache.",
		}),
		accessesTotal: prometheus.NewDesc(
			prometheus.BuildFQName(namespace, "", "accesses_total"),
			"Current total apache accesses",
			nil,
			nil),
		kBytesTotal: prometheus.NewDesc(
			prometheus.BuildFQName(namespace, "", "sent_kilobytes_total"),
			"Current total kbytes sent",
			nil,
			nil),
		uptime: prometheus.NewDesc(
			prometheus.BuildFQName(namespace, "", "uptime_seconds_total"),
			"Current uptime in seconds",
			nil,
			nil),
		workers: prometheus.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "workers",
			Help:      "Apache worker statuses",
		},
			[]string{"state"},
		),
		scoreboard: prometheus.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "scoreboard",
			Help:      "Apache scoreboard statuses",
		},
			[]string{"state"},
		),
		connections: prometheus.NewGaugeVec(prometheus.GaugeOpts{
			Namespace: namespace,
			Name:      "connections",
			Help:      "Apache connection statuses",
		},
			[]string{"state"},
		),
		client: &http.Client{
			Transport: &http.Transport{
				TLSClientConfig: &tls.Config{InsecureSkipVerify: *insecure},
			},
		},
	}
}

// NewNotificationHandler constructs a new NotificationHandler.
func NewNotificationHandler(o *NotificationHandlerOptions) *NotificationHandler {
	return &NotificationHandler{
		alertmanagerURL:      strings.TrimRight(o.AlertmanagerURL, "/"),
		pendingNotifications: make(chan NotificationReqs, o.QueueCapacity),

		httpClient: httputil.NewDeadlineClient(o.Deadline, nil),

		notificationLatency: prometheus.NewSummary(prometheus.SummaryOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "latency_milliseconds",
			Help:      "Latency quantiles for sending alert notifications (not including dropped notifications).",
		}),
		notificationErrors: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "errors_total",
			Help:      "Total number of errors sending alert notifications.",
		}),
		notificationDropped: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "dropped_total",
			Help:      "Total number of alert notifications dropped due to alert manager missing in configuration.",
		}),
		notificationsQueueLength: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: namespace,
			Subsystem: subsystem,
			Name:      "queue_length",
			Help:      "The number of alert notifications in the queue.",
		}),
		notificationsQueueCapacity: prometheus.MustNewConstMetric(
			prometheus.NewDesc(
				prometheus.BuildFQName(namespace, subsystem, "queue_capacity"),
				"The capacity of the alert notifications queue.",
				nil, nil,
			),
			prometheus.GaugeValue,
			float64(o.QueueCapacity),
		),
		stopped: make(chan struct{}),
	}
}

// Takes a prometheus registry and returns a new Collector exposing
// network device stats.
func NewStatCollector() (Collector, error) {
	return &statCollector{
		cpu: prometheus.NewCounterVec(
			prometheus.CounterOpts{
				Namespace: Namespace,
				Name:      "cpu",
				Help:      "Seconds the cpus spent in each mode.",
			},
			[]string{"cpu", "mode"},
		),
		intr: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: Namespace,
			Name:      "intr",
			Help:      "Total number of interrupts serviced.",
		}),
		ctxt: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: Namespace,
			Name:      "context_switches",
			Help:      "Total number of context switches.",
		}),
		forks: prometheus.NewCounter(prometheus.CounterOpts{
			Namespace: Namespace,
			Name:      "forks",
			Help:      "Total number of forks.",
		}),
		btime: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: Namespace,
			Name:      "boot_time",
			Help:      "Node boot time, in unixtime.",
		}),
		procsRunning: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: Namespace,
			Name:      "procs_running",
			Help:      "Number of processes in runnable state.",
		}),
		procsBlocked: prometheus.NewGauge(prometheus.GaugeOpts{
			Namespace: Namespace,
			Name:      "procs_blocked",
			Help:      "Number of processes blocked waiting for I/O to complete.",
		}),
	}, nil
}