Introduce Scraper interface

Signed-off-by: Kamil Dziedzic <arvenil@klecza.pl>

collector/binlog.go

@@ -38,7 +38,20 @@ var (
 )
 
 // ScrapeBinlogSize colects from `SHOW BINARY LOGS`.
-func ScrapeBinlogSize(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeBinlogSize struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeBinlogSize) Name() string {
+	return "binlog_size"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeBinlogSize) Help() string {
+	return "Collect the current size of all registered binlog files"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeBinlogSize) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	var logBin uint8
 	err := db.QueryRow(logbinQuery).Scan(&logBin)
 	if err != nil {

collector/binlog_test.go

@@ -27,7 +27,7 @@ func TestScrapeBinlogSize(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeBinlogSize(db, ch); err != nil {
+		if err = (ScrapeBinlogSize{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/engine_innodb.go

@@ -19,7 +19,20 @@ const (
 )
 
 // ScrapeEngineInnodbStatus scrapes from `SHOW ENGINE INNODB STATUS`.
-func ScrapeEngineInnodbStatus(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeEngineInnodbStatus struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeEngineInnodbStatus) Name() string {
+	return "engine_innodb_status"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeEngineInnodbStatus) Help() string {
+	return "Collect from SHOW ENGINE INNODB STATUS"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeEngineInnodbStatus) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	rows, err := db.Query(engineInnodbStatusQuery)
 	if err != nil {
 		return err

collector/engine_innodb_test.go

@@ -140,7 +140,7 @@ END OF INNODB MONITOR OUTPUT
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeEngineInnodbStatus(db, ch); err != nil {
+		if err = (ScrapeEngineInnodbStatus{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/engine_tokudb.go

@@ -16,26 +16,21 @@ const (
 	engineTokudbStatusQuery = `SHOW ENGINE TOKUDB STATUS`
 )
 
-func sanitizeTokudbMetric(metricName string) string {
-	replacements := map[string]string{
-		">": "",
-		",": "",
-		":": "",
-		"(": "",
-		")": "",
-		" ": "_",
-		"-": "_",
-		"+": "and",
-		"/": "and",
-	}
-	for r := range replacements {
-		metricName = strings.Replace(metricName, r, replacements[r], -1)
-	}
-	return metricName
+// ScrapeEngineTokudbStatus scrapes from `SHOW ENGINE TOKUDB STATUS`.
+type ScrapeEngineTokudbStatus struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeEngineTokudbStatus) Name() string {
+	return "engine_tokudb_status"
 }
 
-// ScrapeEngineTokudbStatus scrapes from `SHOW ENGINE TOKUDB STATUS`.
-func ScrapeEngineTokudbStatus(db *sql.DB, ch chan<- prometheus.Metric) error {
+// Help describes the role of the Scraper.
+func (ScrapeEngineTokudbStatus) Help() string {
+	return "Collect from SHOW ENGINE TOKUDB STATUS"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeEngineTokudbStatus) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	tokudbRows, err := db.Query(engineTokudbStatusQuery)
 	if err != nil {
 		return err
@@ -60,3 +55,21 @@ func ScrapeEngineTokudbStatus(db *sql.DB, ch chan<- prometheus.Metric) error {
 	}
 	return nil
 }
+
+func sanitizeTokudbMetric(metricName string) string {
+	replacements := map[string]string{
+		">": "",
+		",": "",
+		":": "",
+		"(": "",
+		")": "",
+		" ": "_",
+		"-": "_",
+		"+": "and",
+		"/": "and",
+	}
+	for r := range replacements {
+		metricName = strings.Replace(metricName, r, replacements[r], -1)
+	}
+	return metricName
+}

collector/engine_tokudb_test.go

@@ -44,7 +44,7 @@ func TestScrapeEngineTokudbStatus(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeEngineTokudbStatus(db, ch); err != nil {
+		if err = (ScrapeEngineTokudbStatus{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/exporter.go

@@ -4,6 +4,7 @@ import (
 	"database/sql"
 	"fmt"
 	"strings"
+	"sync"
 	"time"
 
 	_ "github.com/go-sql-driver/mysql"
@@ -28,7 +29,7 @@ const (
 	upQuery = `SELECT 1`
 )
 
-// Metric descriptors.
+// Tunable flags.
 var (
 	exporterLockTimeout = kingpin.Flag(
 		"exporter.lock_wait_timeout",
@@ -38,7 +39,10 @@ var (
 		"exporter.log_slow_filter",
 		"Add a log_slow_filter to avoid slow query logging of scrapes. NOTE: Not supported by Oracle MySQL.",
 	).Default("false").Bool()
+)
 
+// Metric descriptors.
+var (
 	scrapeDurationDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, exporter, "collector_duration_seconds"),
 		"Collector time duration.",
@@ -46,42 +50,10 @@ var (
 	)
 )
 
-// Collect defines which metrics we should collect
-type Collect struct {
-	Processlist             bool
-	TableSchema             bool
-	InnodbTablespaces       bool
-	InnodbMetrics           bool
-	GlobalStatus            bool
-	GlobalVariables         bool
-	SlaveStatus             bool
-	AutoIncrementColumns    bool
-	BinlogSize              bool
-	PerfTableIOWaits        bool
-	PerfIndexIOWaits        bool
-	PerfTableLockWaits      bool
-	PerfEventsStatements    bool
-	PerfEventsWaits         bool
-	PerfFileEvents          bool
-	PerfFileInstances       bool
-	PerfRepGroupMemberStats bool
-	UserStat                bool
-	ClientStat              bool
-	TableStat               bool
-	InnodbCmp               bool
-	InnodbCmpMem            bool
-	QueryResponseTime       bool
-	EngineTokudbStatus      bool
-	EngineInnodbStatus      bool
-	Heartbeat               bool
-	HeartbeatDatabase       string
-	HeartbeatTable          string
-}
-
 // Exporter collects MySQL metrics. It implements prometheus.Collector.
 type Exporter struct {
 	dsn          string
-	collect      Collect
+	scrapers     []Scraper
 	error        prometheus.Gauge
 	totalScrapes prometheus.Counter
 	scrapeErrors *prometheus.CounterVec
@@ -89,7 +61,7 @@ type Exporter struct {
 }
 
 // New returns a new MySQL exporter for the provided DSN.
-func New(dsn string, collect Collect) *Exporter {
+func New(dsn string, scrapers []Scraper) *Exporter {
 	// Setup extra params for the DSN, default to having a lock timeout.
 	dsnParams := []string{fmt.Sprintf(timeoutParam, *exporterLockTimeout)}
 
@@ -106,7 +78,7 @@ func New(dsn string, collect Collect) *Exporter {
 
 	return &Exporter{
 		dsn:      dsn,
-		collect: collect,
+		scrapers: scrapers,
 		totalScrapes: prometheus.NewCounter(prometheus.CounterOpts{
 			Namespace: namespace,
 			Subsystem: exporter,
@@ -203,237 +175,20 @@ func (e *Exporter) scrape(ch chan<- prometheus.Metric) {
 
 	ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "connection")
 
-	if e.collect.GlobalStatus {
-		scrapeTime = time.Now()
-		if err = ScrapeGlobalStatus(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.global_status:", err)
-			e.scrapeErrors.WithLabelValues("collect.global_status").Inc()
+	wg := &sync.WaitGroup{}
+	defer wg.Wait()
+	for _, scraper := range e.scrapers {
+		wg.Add(1)
+		go func(scraper Scraper) {
+			defer wg.Done()
+			label := "collect." + scraper.Name()
+			scrapeTime := time.Now()
+			if err := scraper.Scrape(db, ch); err != nil {
+				log.Errorln("Error scraping for "+label+":", err)
+				e.scrapeErrors.WithLabelValues(label).Inc()
 				e.error.Set(1)
 			}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.global_status")
-	}
-	if e.collect.GlobalVariables {
-		scrapeTime = time.Now()
-		if err = ScrapeGlobalVariables(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.global_variables:", err)
-			e.scrapeErrors.WithLabelValues("collect.global_variables").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.global_variables")
-	}
-	if e.collect.SlaveStatus {
-		scrapeTime = time.Now()
-		if err = ScrapeSlaveStatus(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.slave_status:", err)
-			e.scrapeErrors.WithLabelValues("collect.slave_status").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.slave_status")
-	}
-	if e.collect.Processlist {
-		scrapeTime = time.Now()
-		if err = ScrapeProcesslist(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.processlist:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.processlist").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.processlist")
-	}
-	if e.collect.TableSchema {
-		scrapeTime = time.Now()
-		if err = ScrapeTableSchema(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.tables:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.tables").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.tables")
-	}
-	if e.collect.InnodbTablespaces {
-		scrapeTime = time.Now()
-		if err = ScrapeInfoSchemaInnodbTablespaces(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.innodb_sys_tablespaces:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.innodb_sys_tablespaces").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.innodb_sys_tablespaces")
-	}
-	if e.collect.InnodbMetrics {
-		if err = ScrapeInnodbMetrics(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.innodb_metrics:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.innodb_metrics").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.innodb_metrics")
-	}
-	if e.collect.AutoIncrementColumns {
-		scrapeTime = time.Now()
-		if err = ScrapeAutoIncrementColumns(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.auto_increment.columns:", err)
-			e.scrapeErrors.WithLabelValues("collect.auto_increment.columns").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.auto_increment.columns")
-	}
-	if e.collect.BinlogSize {
-		scrapeTime = time.Now()
-		if err = ScrapeBinlogSize(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.binlog_size:", err)
-			e.scrapeErrors.WithLabelValues("collect.binlog_size").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.binlog_size")
-	}
-	if e.collect.PerfTableIOWaits {
-		scrapeTime = time.Now()
-		if err = ScrapePerfTableIOWaits(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.perf_schema.tableiowaits:", err)
-			e.scrapeErrors.WithLabelValues("collect.perf_schema.tableiowaits").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.perf_schema.tableiowaits")
-	}
-	if e.collect.PerfIndexIOWaits {
-		scrapeTime = time.Now()
-		if err = ScrapePerfIndexIOWaits(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.perf_schema.indexiowaits:", err)
-			e.scrapeErrors.WithLabelValues("collect.perf_schema.indexiowaits").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.perf_schema.indexiowaits")
-	}
-	if e.collect.PerfTableLockWaits {
-		scrapeTime = time.Now()
-		if err = ScrapePerfTableLockWaits(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.perf_schema.tablelocks:", err)
-			e.scrapeErrors.WithLabelValues("collect.perf_schema.tablelocks").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.perf_schema.tablelocks")
-	}
-	if e.collect.PerfEventsStatements {
-		scrapeTime = time.Now()
-		if err = ScrapePerfEventsStatements(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.perf_schema.eventsstatements:", err)
-			e.scrapeErrors.WithLabelValues("collect.perf_schema.eventsstatements").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.perf_schema.eventsstatements")
-	}
-	if e.collect.PerfEventsWaits {
-		scrapeTime = time.Now()
-		if err = ScrapePerfEventsWaits(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.perf_schema.eventswaits:", err)
-			e.scrapeErrors.WithLabelValues("collect.perf_schema.eventswaits").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.perf_schema.eventswaits")
-	}
-	if e.collect.PerfFileEvents {
-		scrapeTime = time.Now()
-		if err = ScrapePerfFileEvents(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.perf_schema.file_events:", err)
-			e.scrapeErrors.WithLabelValues("collect.perf_schema.file_events").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.perf_schema.file_events")
-	}
-	if e.collect.PerfFileInstances {
-		scrapeTime = time.Now()
-		if err = ScrapePerfFileInstances(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.perf_schema.file_instances:", err)
-			e.scrapeErrors.WithLabelValues("collect.perf_schema.file_instances").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.perf_schema.file_instances")
-	}
-	if e.collect.PerfRepGroupMemberStats {
-		scrapeTime = time.Now()
-		if err = ScrapeReplicationGroupMemberStats(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.replication_group_member_stats:", err)
-			e.scrapeErrors.WithLabelValues("collect.replication_group_member_stats").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.replication_group_member_stats")
-	}
-	if e.collect.UserStat {
-		scrapeTime = time.Now()
-		if err = ScrapeUserStat(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.userstats:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.userstats").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.userstats")
-	}
-	if e.collect.InnodbCmp {
-		scrapeTime = time.Now()
-		if err = ScrapeInnodbCmp(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.innodbcmp:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.innodbcmp").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.innodbcmp")
-	}
-	if e.collect.InnodbCmpMem {
-		scrapeTime = time.Now()
-		if err = ScrapeInnodbCmpMem(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.innodbcmpmem:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.innodbcmpmem").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.innodbcmpmem")
-	}
-	if e.collect.ClientStat {
-		scrapeTime = time.Now()
-		if err = ScrapeClientStat(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.clientstats:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.clientstats").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.clientstats")
-	}
-	if e.collect.TableStat {
-		scrapeTime = time.Now()
-		if err = ScrapeTableStat(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.tablestats:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.tablestats").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.tablestats")
-	}
-	if e.collect.QueryResponseTime {
-		scrapeTime = time.Now()
-		if err = ScrapeQueryResponseTime(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.info_schema.query_response_time:", err)
-			e.scrapeErrors.WithLabelValues("collect.info_schema.query_response_time").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.info_schema.query_response_time")
-	}
-	if e.collect.EngineTokudbStatus {
-		scrapeTime = time.Now()
-		if err = ScrapeEngineTokudbStatus(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.engine_tokudb_status:", err)
-			e.scrapeErrors.WithLabelValues("collect.engine_tokudb_status").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.engine_tokudb_status")
-	}
-	if e.collect.EngineInnodbStatus {
-		scrapeTime = time.Now()
-		if err = ScrapeEngineInnodbStatus(db, ch); err != nil {
-			log.Errorln("Error scraping for collect.engine_innodb_status:", err)
-			e.scrapeErrors.WithLabelValues("collect.engine_innodb_status").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.engine_innodb_status")
-	}
-	if e.collect.Heartbeat {
-		scrapeTime = time.Now()
-		if err = ScrapeHeartbeat(db, ch, e.collect.HeartbeatDatabase, e.collect.HeartbeatTable); err != nil {
-			log.Errorln("Error scraping for collect.heartbeat:", err)
-			e.scrapeErrors.WithLabelValues("collect.heartbeat").Inc()
-			e.error.Set(1)
-		}
-		ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "collect.heartbeat")
+			ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), label)
+		}(scraper)
 	}
 }

collector/exporter_test.go

@@ -15,8 +15,8 @@ func TestExporter(t *testing.T) {
 		t.Skip("-short is passed, skipping test")
 	}
 
-	exporter := New(dsn, Collect{
-		GlobalStatus: true,
+	exporter := New(dsn, []Scraper{
+		ScrapeGlobalStatus{},
 	})
 
 	convey.Convey("Metrics describing", t, func() {

collector/global_status.go

@@ -11,7 +11,7 @@ import (
 )
 
 const (
-	// Scrape query
+	// Scrape query.
 	globalStatusQuery = `SHOW GLOBAL STATUS`
 	// Subsystem.
 	globalStatus = "global_status"
@@ -20,6 +20,7 @@ const (
 // Regexp to match various groups of status vars.
 var globalStatusRE = regexp.MustCompile(`^(com|handler|connection_errors|innodb_buffer_pool_pages|innodb_rows|performance_schema)_(.*)$`)
 
+// Metric descriptors.
 var (
 	globalCommandsDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, globalStatus, "commands_total"),
@@ -59,7 +60,20 @@ var (
 )
 
 // ScrapeGlobalStatus collects from `SHOW GLOBAL STATUS`.
-func ScrapeGlobalStatus(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeGlobalStatus struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeGlobalStatus) Name() string {
+	return globalStatus
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeGlobalStatus) Help() string {
+	return "Collect from SHOW GLOBAL STATUS"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeGlobalStatus) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	globalStatusRows, err := db.Query(globalStatusQuery)
 	if err != nil {
 		return err

collector/global_status_test.go

@@ -38,7 +38,7 @@ func TestScrapeGlobalStatus(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeGlobalStatus(db, ch); err != nil {
+		if err = (ScrapeGlobalStatus{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/global_variables.go

@@ -19,7 +19,20 @@ const (
 )
 
 // ScrapeGlobalVariables collects from `SHOW GLOBAL VARIABLES`.
-func ScrapeGlobalVariables(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeGlobalVariables struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeGlobalVariables) Name() string {
+	return globalVariables
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeGlobalVariables) Help() string {
+	return "Collect from SHOW GLOBAL VARIABLES"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeGlobalVariables) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	globalVariablesRows, err := db.Query(globalVariablesQuery)
 	if err != nil {
 		return err

collector/global_variables_test.go

@@ -37,7 +37,7 @@ func TestScrapeGlobalVariables(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeGlobalVariables(db, ch); err != nil {
+		if err = (ScrapeGlobalVariables{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/heartbeat.go

@@ -8,6 +8,7 @@ import (
 	"strconv"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"gopkg.in/alecthomas/kingpin.v2"
 )
 
 const (
@@ -20,6 +21,17 @@ const (
 	heartbeatQuery = "SELECT UNIX_TIMESTAMP(ts), UNIX_TIMESTAMP(NOW(6)), server_id from `%s`.`%s`"
 )
 
+var (
+	collectHeartbeatDatabase = kingpin.Flag(
+		"collect.heartbeat.database",
+		"Database from where to collect heartbeat data",
+	).Default("heartbeat").String()
+	collectHeartbeatTable = kingpin.Flag(
+		"collect.heartbeat.table",
+		"Table from where to collect heartbeat data",
+	).Default("heartbeat").String()
+)
+
 // Metric descriptors.
 var (
 	HeartbeatStoredDesc = prometheus.NewDesc(
@@ -41,8 +53,21 @@ var (
 //  ts                    varchar(26) NOT NULL,
 //  server_id             int unsigned NOT NULL PRIMARY KEY,
 // );
-func ScrapeHeartbeat(db *sql.DB, ch chan<- prometheus.Metric, collectDatabase, collectTable string) error {
-	query := fmt.Sprintf(heartbeatQuery, collectDatabase, collectTable)
+type ScrapeHeartbeat struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeHeartbeat) Name() string {
+	return "heartbeat"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeHeartbeat) Help() string {
+	return "Collect from heartbeat"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeHeartbeat) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
+	query := fmt.Sprintf(heartbeatQuery, *collectHeartbeatDatabase, *collectHeartbeatTable)
 	heartbeatRows, err := db.Query(query)
 	if err != nil {
 		return err

collector/heartbeat_test.go

@@ -7,9 +7,18 @@ import (
 	dto "github.com/prometheus/client_model/go"
 	"github.com/smartystreets/goconvey/convey"
 	"gopkg.in/DATA-DOG/go-sqlmock.v1"
+	"gopkg.in/alecthomas/kingpin.v2"
 )
 
 func TestScrapeHeartbeat(t *testing.T) {
+	_, err := kingpin.CommandLine.Parse([]string{
+		"--collect.heartbeat.database", "heartbeat-test",
+		"--collect.heartbeat.table", "heartbeat-test",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	db, mock, err := sqlmock.New()
 	if err != nil {
 		t.Fatalf("error opening a stub database connection: %s", err)
@@ -19,13 +28,11 @@ func TestScrapeHeartbeat(t *testing.T) {
 	columns := []string{"UNIX_TIMESTAMP(ts)", "UNIX_TIMESTAMP(NOW(6))", "server_id"}
 	rows := sqlmock.NewRows(columns).
 		AddRow("1487597613.001320", "1487598113.448042", 1)
-	mock.ExpectQuery(sanitizeQuery("SELECT UNIX_TIMESTAMP(ts), UNIX_TIMESTAMP(NOW(6)), server_id from `heartbeat`.`heartbeat`")).WillReturnRows(rows)
+	mock.ExpectQuery(sanitizeQuery("SELECT UNIX_TIMESTAMP(ts), UNIX_TIMESTAMP(NOW(6)), server_id from `heartbeat-test`.`heartbeat-test`")).WillReturnRows(rows)
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		database := "heartbeat"
-		table := "heartbeat"
-		if err = ScrapeHeartbeat(db, ch, database, table); err != nil {
+		if err = (ScrapeHeartbeat{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_auto_increment.go

@@ -22,6 +22,7 @@ const infoSchemaAutoIncrementQuery = `
 		  WHERE c.extra = 'auto_increment' AND t.auto_increment IS NOT NULL
 		`
 
+// Metric descriptors.
 var (
 	globalInfoSchemaAutoIncrementDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, informationSchema, "auto_increment_column"),
@@ -36,7 +37,20 @@ var (
 )
 
 // ScrapeAutoIncrementColumns collects auto_increment column information.
-func ScrapeAutoIncrementColumns(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeAutoIncrementColumns struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeAutoIncrementColumns) Name() string {
+	return "auto_increment.columns"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeAutoIncrementColumns) Help() string {
+	return "Collect auto_increment columns and max values from information_schema"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeAutoIncrementColumns) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	autoIncrementRows, err := db.Query(infoSchemaAutoIncrementQuery)
 	if err != nil {
 		return err

collector/info_schema_clientstats.go

@@ -128,7 +128,20 @@ var (
 )
 
 // ScrapeClientStat collects from `information_schema.client_statistics`.
-func ScrapeClientStat(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeClientStat struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeClientStat) Name() string {
+	return "info_schema.clientstats"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeClientStat) Help() string {
+	return "If running with userstat=1, set to true to collect client statistics"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeClientStat) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	var varName, varVal string
 	err := db.QueryRow(userstatCheckQuery).Scan(&varName, &varVal)
 	if err != nil {

collector/info_schema_clientstats_test.go

@@ -26,7 +26,7 @@ func TestScrapeClientStat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeClientStat(db, ch); err != nil {
+		if err = (ScrapeClientStat{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_innodb_cmp.go

@@ -14,6 +14,7 @@ const innodbCmpQuery = `
 		  FROM information_schema.innodb_cmp
 		`
 
+// Metric descriptors.
 var (
 	infoSchemaInnodbCmpCompressOps = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, informationSchema, "innodb_cmp_compress_ops_total"),
@@ -43,7 +44,20 @@ var (
 )
 
 // ScrapeInnodbCmp collects from `information_schema.innodb_cmp`.
-func ScrapeInnodbCmp(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeInnodbCmp struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeInnodbCmp) Name() string {
+	return informationSchema + ".innodb_cmp"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeInnodbCmp) Help() string {
+	return "Collect metrics from information_schema.innodb_cmp"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeInnodbCmp) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 
 	informationSchemaInnodbCmpRows, err := db.Query(innodbCmpQuery)
 	if err != nil {

collector/info_schema_innodb_cmp_test.go

@@ -23,7 +23,7 @@ func TestScrapeInnodbCmp(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeInnodbCmp(db, ch); err != nil {
+		if err = (ScrapeInnodbCmp{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_innodb_cmpmem.go

@@ -14,6 +14,7 @@ const innodbCmpMemQuery = `
                   FROM information_schema.innodb_cmpmem
                 `
 
+// Metric descriptors.
 var (
 	infoSchemaInnodbCmpMemPagesRead = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, informationSchema, "innodb_cmpmem_pages_used_total"),
@@ -38,7 +39,20 @@ var (
 )
 
 // ScrapeInnodbCmp collects from `information_schema.innodb_cmp`.
-func ScrapeInnodbCmpMem(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeInnodbCmpMem struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeInnodbCmpMem) Name() string {
+	return informationSchema + ".innodb_cmpmem"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeInnodbCmpMem) Help() string {
+	return "Collect metrics from information_schema.innodb_cmpmem"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeInnodbCmpMem) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 
 	informationSchemaInnodbCmpMemRows, err := db.Query(innodbCmpMemQuery)
 	if err != nil {

collector/info_schema_innodb_cmpmem_test.go

@@ -23,7 +23,7 @@ func TestScrapeInnodbCmpMem(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeInnodbCmpMem(db, ch); err != nil {
+		if err = (ScrapeInnodbCmpMem{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_innodb_metrics.go

@@ -49,7 +49,20 @@ var (
 )
 
 // ScrapeInnodbMetrics collects from `information_schema.innodb_metrics`.
-func ScrapeInnodbMetrics(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeInnodbMetrics struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeInnodbMetrics) Name() string {
+	return informationSchema + ".innodb_metrics"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeInnodbMetrics) Help() string {
+	return "Collect metrics from information_schema.innodb_metrics"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeInnodbMetrics) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	innodbMetricsRows, err := db.Query(infoSchemaInnodbMetricsQuery)
 	if err != nil {
 		return err

collector/info_schema_innodb_metrics_test.go

@@ -40,7 +40,7 @@ func TestScrapeInnodbMetrics(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeInnodbMetrics(db, ch); err != nil {
+		if err = (ScrapeInnodbMetrics{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_innodb_sys_tablespaces.go

@@ -20,6 +20,7 @@ const innodbTablespacesQuery = `
 	  FROM information_schema.innodb_sys_tablespaces
 	`
 
+// Metric descriptors.
 var (
 	infoSchemaInnodbTablesspaceInfoDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, informationSchema, "innodb_tablespace_space_info"),
@@ -39,7 +40,20 @@ var (
 )
 
 // ScrapeInfoSchemaInnodbTablespaces collects from `information_schema.innodb_sys_tablespaces`.
-func ScrapeInfoSchemaInnodbTablespaces(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeInfoSchemaInnodbTablespaces struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeInfoSchemaInnodbTablespaces) Name() string {
+	return informationSchema + ".innodb_tablespaces"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeInfoSchemaInnodbTablespaces) Help() string {
+	return "Collect metrics from information_schema.innodb_sys_tablespaces"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeInfoSchemaInnodbTablespaces) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	tablespacesRows, err := db.Query(innodbTablespacesQuery)
 	if err != nil {
 		return err

collector/info_schema_innodb_sys_tablespaces_test.go

@@ -24,7 +24,7 @@ func TestScrapeInfoSchemaInnodbTablespaces(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeInfoSchemaInnodbTablespaces(db, ch); err != nil {
+		if err = (ScrapeInfoSchemaInnodbTablespaces{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_processlist.go

@@ -20,13 +20,16 @@ const infoSchemaProcesslistQuery = `
 		  ORDER BY null
 		`
 
-var (
 // Tunable flags.
+var (
 	processlistMinTime = kingpin.Flag(
 		"collect.info_schema.processlist.min_time",
 		"Minimum time a thread must be in each state to be counted",
 	).Default("0").Int()
-	// Prometheus descriptors.
+)
+
+// Metric descriptors.
+var (
 	processlistCountDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, informationSchema, "threads"),
 		"The number of threads (connections) split by current state.",
@@ -118,37 +121,21 @@ var (
 	}
 )
 
-func deriveThreadState(command string, state string) string {
-	var normCmd = strings.Replace(strings.ToLower(command), "_", " ", -1)
-	var normState = strings.Replace(strings.ToLower(state), "_", " ", -1)
-	// check if it's already a valid state
-	_, knownState := threadStateCounterMap[normState]
-	if knownState {
-		return normState
-	}
-	// check if plain mapping applies
-	mappedState, canMap := threadStateMapping[normState]
-	if canMap {
-		return mappedState
-	}
-	// check special waiting for XYZ lock
-	if strings.Contains(normState, "waiting for") && strings.Contains(normState, "lock") {
-		return "waiting for lock"
-	}
-	if normCmd == "sleep" && normState == "" {
-		return "idle"
-	}
-	if normCmd == "query" {
-		return "executing"
-	}
-	if normCmd == "binlog dump" {
-		return "replication master"
-	}
-	return "other"
+// ScrapeProcesslist collects from `information_schema.processlist`.
+type ScrapeProcesslist struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeProcesslist) Name() string {
+	return informationSchema + ".processlist"
 }
 
-// ScrapeProcesslist collects from `information_schema.processlist`.
-func ScrapeProcesslist(db *sql.DB, ch chan<- prometheus.Metric) error {
+// Help describes the role of the Scraper.
+func (ScrapeProcesslist) Help() string {
+	return "Collect current thread state counts from the information_schema.processlist"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeProcesslist) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	processQuery := fmt.Sprintf(
 		infoSchemaProcesslistQuery,
 		*processlistMinTime,
@@ -191,3 +178,32 @@ func ScrapeProcesslist(db *sql.DB, ch chan<- prometheus.Metric) error {
 
 	return nil
 }
+
+func deriveThreadState(command string, state string) string {
+	var normCmd = strings.Replace(strings.ToLower(command), "_", " ", -1)
+	var normState = strings.Replace(strings.ToLower(state), "_", " ", -1)
+	// check if it's already a valid state
+	_, knownState := threadStateCounterMap[normState]
+	if knownState {
+		return normState
+	}
+	// check if plain mapping applies
+	mappedState, canMap := threadStateMapping[normState]
+	if canMap {
+		return mappedState
+	}
+	// check special waiting for XYZ lock
+	if strings.Contains(normState, "waiting for") && strings.Contains(normState, "lock") {
+		return "waiting for lock"
+	}
+	if normCmd == "sleep" && normState == "" {
+		return "idle"
+	}
+	if normCmd == "query" {
+		return "executing"
+	}
+	if normCmd == "binlog dump" {
+		return "replication master"
+	}
+	return "other"
+}

collector/info_schema_query_response_time.go

@@ -86,7 +86,20 @@ func processQueryResponseTimeTable(db *sql.DB, ch chan<- prometheus.Metric, quer
 }
 
 // ScrapeQueryResponseTime collects from `information_schema.query_response_time`.
-func ScrapeQueryResponseTime(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeQueryResponseTime struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeQueryResponseTime) Name() string {
+	return "info_schema.query_response_time"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeQueryResponseTime) Help() string {
+	return "Collect query response time distribution if query_response_time_stats is ON."
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeQueryResponseTime) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	var queryStats uint8
 	err := db.QueryRow(queryResponseCheckQuery).Scan(&queryStats)
 	if err != nil {

collector/info_schema_query_response_time_test.go

@@ -37,7 +37,7 @@ func TestScrapeQueryResponseTime(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeQueryResponseTime(db, ch); err != nil {
+		if err = (ScrapeQueryResponseTime{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_tables.go

@@ -36,11 +36,16 @@ const (
 		`
 )
 
+// Tunable flags.
 var (
 	tableSchemaDatabases = kingpin.Flag(
 		"collect.info_schema.tables.databases",
 		"The list of databases to collect table stats for, or '*' for all",
 	).Default("*").String()
+)
+
+// Metric descriptors.
+var (
 	infoSchemaTablesVersionDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, informationSchema, "table_version"),
 		"The version number of the table's .frm file",
@@ -59,7 +64,20 @@ var (
 )
 
 // ScrapeTableSchema collects from `information_schema.tables`.
-func ScrapeTableSchema(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeTableSchema struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeTableSchema) Name() string {
+	return informationSchema + ".tables"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeTableSchema) Help() string {
+	return "Collect metrics from information_schema.tables"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeTableSchema) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	var dbList []string
 	if *tableSchemaDatabases == "*" {
 		dbListRows, err := db.Query(dbListQuery)

collector/info_schema_tablestats.go

@@ -19,6 +19,7 @@ const tableStatQuery = `
 		  FROM information_schema.table_statistics
 		`
 
+// Metric descriptors.
 var (
 	infoSchemaTableStatsRowsReadDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, informationSchema, "table_statistics_rows_read_total"),
@@ -38,7 +39,20 @@ var (
 )
 
 // ScrapeTableStat collects from `information_schema.table_statistics`.
-func ScrapeTableStat(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeTableStat struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeTableStat) Name() string {
+	return "info_schema.tablestats"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeTableStat) Help() string {
+	return "If running with userstat=1, set to true to collect table statistics"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeTableStat) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	var varName, varVal string
 	err := db.QueryRow(userstatCheckQuery).Scan(&varName, &varVal)
 	if err != nil {

collector/info_schema_tablestats_test.go

@@ -27,7 +27,7 @@ func TestScrapeTableStat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeTableStat(db, ch); err != nil {
+		if err = (ScrapeTableStat{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_userstats.go

@@ -124,7 +124,20 @@ var (
 )
 
 // ScrapeUserStat collects from `information_schema.user_statistics`.
-func ScrapeUserStat(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeUserStat struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeUserStat) Name() string {
+	return "info_schema.userstats"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeUserStat) Help() string {
+	return "If running with userstat=1, set to true to collect user statistics"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeUserStat) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	var varName, varVal string
 	err := db.QueryRow(userstatCheckQuery).Scan(&varName, &varVal)
 	if err != nil {

collector/info_schema_userstats_test.go

@@ -26,7 +26,7 @@ func TestScrapeUserStat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeUserStat(db, ch); err != nil {
+		if err = (ScrapeUserStat{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/perf_schema_events_statements.go

@@ -54,7 +54,7 @@ const perfEventsStatementsQuery = `
 	  LIMIT %d
 	`
 
-// Tuning flags.
+// Tunable flags.
 var (
 	perfEventsStatementsLimit = kingpin.Flag(
 		"collect.perf_schema.eventsstatements.limit",
@@ -135,7 +135,20 @@ var (
 )
 
 // ScrapePerfEventsStatements collects from `performance_schema.events_statements_summary_by_digest`.
-func ScrapePerfEventsStatements(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapePerfEventsStatements struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapePerfEventsStatements) Name() string {
+	return "perf_schema.eventsstatements"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapePerfEventsStatements) Help() string {
+	return "Collect metrics from performance_schema.events_statements_summary_by_digest"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapePerfEventsStatements) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	perfQuery := fmt.Sprintf(
 		perfEventsStatementsQuery,
 		*perfEventsStatementsDigestTextLimit,

collector/perf_schema_events_waits.go

@@ -28,7 +28,20 @@ var (
 )
 
 // ScrapePerfEventsWaits collects from `performance_schema.events_waits_summary_global_by_event_name`.
-func ScrapePerfEventsWaits(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapePerfEventsWaits struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapePerfEventsWaits) Name() string {
+	return "perf_schema.eventswaits"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapePerfEventsWaits) Help() string {
+	return "Collect metrics from performance_schema.events_waits_summary_global_by_event_name"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapePerfEventsWaits) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	// Timers here are returned in picoseconds.
 	perfSchemaEventsWaitsRows, err := db.Query(perfEventsWaitsQuery)
 	if err != nil {

collector/perf_schema_file_events.go

@@ -37,7 +37,20 @@ var (
 )
 
 // ScrapePerfFileEvents collects from `performance_schema.file_summary_by_event_name`.
-func ScrapePerfFileEvents(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapePerfFileEvents struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapePerfFileEvents) Name() string {
+	return "perf_schema.file_events"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapePerfFileEvents) Help() string {
+	return "Collect metrics from performance_schema.file_summary_by_event_name"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapePerfFileEvents) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	// Timers here are returned in picoseconds.
 	perfSchemaFileEventsRows, err := db.Query(perfFileEventsQuery)
 	if err != nil {

collector/perf_schema_file_instances.go

@@ -19,13 +19,16 @@ const perfFileInstancesQuery = `
 	     where FILE_NAME REGEXP ?
 	`
 
-// Metric descriptors.
+// Tunable flags.
 var (
 	performanceSchemaFileInstancesFilter = kingpin.Flag(
 		"collect.perf_schema.file_instances.filter",
 		"RegEx file_name filter for performance_schema.file_summary_by_instance",
 	).Default(".*").String()
+)
 
+// Metric descriptors.
+var (
 	performanceSchemaFileInstancesRemovePrefix = kingpin.Flag(
 		"collect.perf_schema.file_instances.remove_prefix",
 		"Remove path prefix in performance_schema.file_summary_by_instance",
@@ -43,8 +46,21 @@ var (
 	)
 )
 
-// ScrapePerfFileEvents collects from `performance_schema.file_summary_by_event_name`.
-func ScrapePerfFileInstances(db *sql.DB, ch chan<- prometheus.Metric) error {
+// ScrapePerfFileInstances collects from `performance_schema.file_summary_by_instance`.
+type ScrapePerfFileInstances struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapePerfFileInstances) Name() string {
+	return "perf_schema.file_instances"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapePerfFileInstances) Help() string {
+	return "Collect metrics from performance_schema.file_summary_by_instance"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapePerfFileInstances) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	// Timers here are returned in picoseconds.
 	perfSchemaFileInstancesRows, err := db.Query(perfFileInstancesQuery, *performanceSchemaFileInstancesFilter)
 	if err != nil {

collector/perf_schema_file_instances_test.go

@@ -33,7 +33,7 @@ func TestScrapePerfFileInstances(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapePerfFileInstances(db, ch); err != nil {
+		if err = (ScrapePerfFileInstances{}).Scrape(db, ch); err != nil {
 			panic(fmt.Sprintf("error calling function on test: %s", err))
 		}
 		close(ch)

collector/perf_schema_index_io_waits.go

@@ -31,7 +31,20 @@ var (
 )
 
 // ScrapePerfIndexIOWaits collects for `performance_schema.table_io_waits_summary_by_index_usage`.
-func ScrapePerfIndexIOWaits(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapePerfIndexIOWaits struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapePerfIndexIOWaits) Name() string {
+	return "perf_schema.indexiowaits"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapePerfIndexIOWaits) Help() string {
+	return "Collect metrics from performance_schema.table_io_waits_summary_by_index_usage"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapePerfIndexIOWaits) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	perfSchemaIndexWaitsRows, err := db.Query(perfIndexIOWaitsQuery)
 	if err != nil {
 		return err

collector/perf_schema_index_io_waits_test.go

@@ -25,7 +25,7 @@ func TestScrapePerfIndexIOWaits(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapePerfIndexIOWaits(db, ch); err != nil {
+		if err = (ScrapePerfIndexIOWaits{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/perf_schema_replication_group_member_stats.go

@@ -37,7 +37,20 @@ var (
 )
 
 // ScrapeReplicationGroupMemberStats collects from `performance_schema.replication_group_member_stats`.
-func ScrapeReplicationGroupMemberStats(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapePerfReplicationGroupMemberStats struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapePerfReplicationGroupMemberStats) Name() string {
+	return performanceSchema + ".replication_group_member_stats"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapePerfReplicationGroupMemberStats) Help() string {
+	return "Collect metrics from performance_schema.replication_group_member_stats"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapePerfReplicationGroupMemberStats) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	perfReplicationGroupMemeberStatsRows, err := db.Query(perfReplicationGroupMemeberStatsQuery)
 	if err != nil {
 		return err
@@ -58,19 +71,19 @@ func ScrapeReplicationGroupMemberStats(db *sql.DB, ch chan<- prometheus.Metric)
 			return err
 		}
 		ch <- prometheus.MustNewConstMetric(
-			performanceSchemaTableWaitsDesc, prometheus.CounterValue, float64(countTransactionsInQueue),
+			performanceSchemaReplicationGroupMemberStatsTransInQueueDesc, prometheus.CounterValue, float64(countTransactionsInQueue),
 			memberId,
 		)
 		ch <- prometheus.MustNewConstMetric(
-			performanceSchemaTableWaitsDesc, prometheus.CounterValue, float64(countTransactionsChecked),
+			performanceSchemaReplicationGroupMemberStatsTransCheckedDesc, prometheus.CounterValue, float64(countTransactionsChecked),
 			memberId,
 		)
 		ch <- prometheus.MustNewConstMetric(
-			performanceSchemaTableWaitsDesc, prometheus.CounterValue, float64(countConflictsDetected),
+			performanceSchemaReplicationGroupMemberStatsConflictsDetectedDesc, prometheus.CounterValue, float64(countConflictsDetected),
 			memberId,
 		)
 		ch <- prometheus.MustNewConstMetric(
-			performanceSchemaTableWaitsDesc, prometheus.CounterValue, float64(countTransactionsRowsValidating),
+			performanceSchemaReplicationGroupMemberStatsTransRowValidatingDesc, prometheus.CounterValue, float64(countTransactionsRowsValidating),
 			memberId,
 		)
 	}

collector/perf_schema_table_io_waits.go

@@ -32,7 +32,20 @@ var (
 )
 
 // ScrapePerfTableIOWaits collects from `performance_schema.table_io_waits_summary_by_table`.
-func ScrapePerfTableIOWaits(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapePerfTableIOWaits struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapePerfTableIOWaits) Name() string {
+	return "perf_schema.tableiowaits"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapePerfTableIOWaits) Help() string {
+	return "Collect metrics from performance_schema.table_io_waits_summary_by_table"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapePerfTableIOWaits) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	perfSchemaTableWaitsRows, err := db.Query(perfTableIOWaitsQuery)
 	if err != nil {
 		return err

collector/perf_schema_table_lock_waits.go

@@ -61,7 +61,20 @@ var (
 )
 
 // ScrapePerfTableLockWaits collects from `performance_schema.table_lock_waits_summary_by_table`.
-func ScrapePerfTableLockWaits(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapePerfTableLockWaits struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapePerfTableLockWaits) Name() string {
+	return "perf_schema.tablelocks"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapePerfTableLockWaits) Help() string {
+	return "Collect metrics from performance_schema.table_lock_waits_summary_by_table"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapePerfTableLockWaits) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	perfSchemaTableLockWaitsRows, err := db.Query(perfTableLockWaitsQuery)
 	if err != nil {
 		return err

collector/scraper.go

@@ -0,0 +1,19 @@
+package collector
+
+import (
+	"database/sql"
+
+	_ "github.com/go-sql-driver/mysql"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// Scraper is minimal interface that let's you add new prometheus metrics to mysqld_exporter.
+type Scraper interface {
+	// Name of the Scraper. Should be unique.
+	Name() string
+	// Help describes the role of the Scraper.
+	// Example: "Collect from SHOW ENGINE INNODB STATUS"
+	Help() string
+	// Scrape collects data from database connection and sends it over channel as prometheus metric.
+	Scrape(db *sql.DB, ch chan<- prometheus.Metric) error
+}

collector/slave_status.go

@@ -36,7 +36,20 @@ func columnValue(scanArgs []interface{}, slaveCols []string, colName string) str
 }
 
 // ScrapeSlaveStatus collects from `SHOW SLAVE STATUS`.
-func ScrapeSlaveStatus(db *sql.DB, ch chan<- prometheus.Metric) error {
+type ScrapeSlaveStatus struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeSlaveStatus) Name() string {
+	return slaveStatus
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeSlaveStatus) Help() string {
+	return "Collect from SHOW SLAVE STATUS"
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeSlaveStatus) Scrape(db *sql.DB, ch chan<- prometheus.Metric) error {
 	var (
 		slaveStatusRows *sql.Rows
 		err             error

collector/slave_status_test.go

@@ -23,7 +23,7 @@ func TestScrapeSlaveStatus(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = ScrapeSlaveStatus(db, ch); err != nil {
+		if err = (ScrapeSlaveStatus{}).Scrape(db, ch); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

mysqld_exporter.go

@@ -29,121 +29,39 @@ var (
 		"config.my-cnf",
 		"Path to .my.cnf file to read MySQL credentials from.",
 	).Default(path.Join(os.Getenv("HOME"), ".my.cnf")).String()
-	collectProcesslist = kingpin.Flag(
-		"collect.info_schema.processlist",
-		"Collect current thread state counts from the information_schema.processlist",
-	).Default("false").Bool()
-	collectTableSchema = kingpin.Flag(
-		"collect.info_schema.tables",
-		"Collect metrics from information_schema.tables",
-	).Default("true").Bool()
-	collectInnodbTablespaces = kingpin.Flag(
-		"collect.info_schema.innodb_tablespaces",
-		"Collect metrics from information_schema.innodb_sys_tablespaces",
-	).Default("false").Bool()
-	collectInnodbMetrics = kingpin.Flag(
-		"collect.info_schema.innodb_metrics",
-		"Collect metrics from information_schema.innodb_metrics",
-	).Default("false").Bool()
-	collectGlobalStatus = kingpin.Flag(
-		"collect.global_status",
-		"Collect from SHOW GLOBAL STATUS",
-	).Default("true").Bool()
-	collectGlobalVariables = kingpin.Flag(
-		"collect.global_variables",
-		"Collect from SHOW GLOBAL VARIABLES",
-	).Default("true").Bool()
-	collectSlaveStatus = kingpin.Flag(
-		"collect.slave_status",
-		"Collect from SHOW SLAVE STATUS",
-	).Default("true").Bool()
-	collectAutoIncrementColumns = kingpin.Flag(
-		"collect.auto_increment.columns",
-		"Collect auto_increment columns and max values from information_schema",
-	).Default("false").Bool()
-	collectBinlogSize = kingpin.Flag(
-		"collect.binlog_size",
-		"Collect the current size of all registered binlog files",
-	).Default("false").Bool()
-	collectPerfTableIOWaits = kingpin.Flag(
-		"collect.perf_schema.tableiowaits",
-		"Collect metrics from performance_schema.table_io_waits_summary_by_table",
-	).Default("false").Bool()
-	collectPerfIndexIOWaits = kingpin.Flag(
-		"collect.perf_schema.indexiowaits",
-		"Collect metrics from performance_schema.table_io_waits_summary_by_index_usage",
-	).Default("false").Bool()
-	collectPerfTableLockWaits = kingpin.Flag(
-		"collect.perf_schema.tablelocks",
-		"Collect metrics from performance_schema.table_lock_waits_summary_by_table",
-	).Default("false").Bool()
-	collectPerfEventsStatements = kingpin.Flag(
-		"collect.perf_schema.eventsstatements",
-		"Collect metrics from performance_schema.events_statements_summary_by_digest",
-	).Default("false").Bool()
-	collectPerfEventsWaits = kingpin.Flag(
-		"collect.perf_schema.eventswaits",
-		"Collect metrics from performance_schema.events_waits_summary_global_by_event_name",
-	).Default("false").Bool()
-	collectPerfFileEvents = kingpin.Flag(
-		"collect.perf_schema.file_events",
-		"Collect metrics from performance_schema.file_summary_by_event_name",
-	).Default("false").Bool()
-	collectPerfFileInstances = kingpin.Flag(
-		"collect.perf_schema.file_instances",
-		"Collect metrics from performance_schema.file_summary_by_instance",
-	).Default("false").Bool()
-	collectPerfRepGroupMemberStats = kingpin.Flag(
-		"collect.replication_group_member_stats",
-		"Collect metrics from performance_schema.replication_group_member_stats",
-	).Default("false").Bool()
-	collectUserStat = kingpin.Flag(
-		"collect.info_schema.userstats",
-		"If running with userstat=1, set to true to collect user statistics",
-	).Default("false").Bool()
-	collectClientStat = kingpin.Flag(
-		"collect.info_schema.clientstats",
-		"If running with userstat=1, set to true to collect client statistics",
-	).Default("false").Bool()
-	collectTableStat = kingpin.Flag(
-		"collect.info_schema.tablestats",
-		"If running with userstat=1, set to true to collect table statistics",
-	).Default("false").Bool()
-	collectQueryResponseTime = kingpin.Flag(
-		"collect.info_schema.query_response_time",
-		"Collect query response time distribution if query_response_time_stats is ON.",
-	).Default("false").Bool()
-	collectInnodbCmp = kingpin.Flag(
-		"collect.info_schema.innodbcmp",
-		"If running with innodbcmp=1, set to true to collect innodb cmp statistics",
-	).Default("false").Bool()
-	collectInnodbCmpMem = kingpin.Flag(
-		"collect.info_schema.innodbcmpmem",
-		"If running with innodbcmpmem=1, set to true to collect innodb cmpmem statistics",
-	).Default("false").Bool()
-	collectEngineTokudbStatus = kingpin.Flag(
-		"collect.engine_tokudb_status",
-		"Collect from SHOW ENGINE TOKUDB STATUS",
-	).Default("false").Bool()
-	collectEngineInnodbStatus = kingpin.Flag(
-		"collect.engine_innodb_status",
-		"Collect from SHOW ENGINE INNODB STATUS",
-	).Default("false").Bool()
-	collectHeartbeat = kingpin.Flag(
-		"collect.heartbeat",
-		"Collect from heartbeat",
-	).Default("false").Bool()
-	collectHeartbeatDatabase = kingpin.Flag(
-		"collect.heartbeat.database",
-		"Database from where to collect heartbeat data",
-	).Default("heartbeat").String()
-	collectHeartbeatTable = kingpin.Flag(
-		"collect.heartbeat.table",
-		"Table from where to collect heartbeat data",
-	).Default("heartbeat").String()
 	dsn string
 )
 
+// scrapers lists all possible collection methods and if they should be enabled by default.
+var scrapers = map[collector.Scraper]bool{
+	collector.ScrapeGlobalStatus{}:                    true,
+	collector.ScrapeGlobalVariables{}:                 true,
+	collector.ScrapeSlaveStatus{}:                     true,
+	collector.ScrapeProcesslist{}:                     false,
+	collector.ScrapeTableSchema{}:                     true,
+	collector.ScrapeInfoSchemaInnodbTablespaces{}:     false,
+	collector.ScrapeInnodbMetrics{}:                   false,
+	collector.ScrapeAutoIncrementColumns{}:            false,
+	collector.ScrapeBinlogSize{}:                      false,
+	collector.ScrapePerfTableIOWaits{}:                false,
+	collector.ScrapePerfIndexIOWaits{}:                false,
+	collector.ScrapePerfTableLockWaits{}:              false,
+	collector.ScrapePerfEventsStatements{}:            false,
+	collector.ScrapePerfEventsWaits{}:                 false,
+	collector.ScrapePerfFileEvents{}:                  false,
+	collector.ScrapePerfFileInstances{}:               false,
+	collector.ScrapePerfReplicationGroupMemberStats{}: false,
+	collector.ScrapeUserStat{}:                        false,
+	collector.ScrapeClientStat{}:                      false,
+	collector.ScrapeTableStat{}:                       false,
+	collector.ScrapeInnodbCmp{}:                       false,
+	collector.ScrapeInnodbCmpMem{}:                    false,
+	collector.ScrapeQueryResponseTime{}:               false,
+	collector.ScrapeEngineTokudbStatus{}:              false,
+	collector.ScrapeEngineInnodbStatus{}:              false,
+	collector.ScrapeHeartbeat{}:                       false,
+}
+
 func parseMycnf(config interface{}) (string, error) {
 	var dsn string
 	cfg, err := ini.Load(config)
@@ -171,58 +89,29 @@ func init() {
 	prometheus.MustRegister(version.NewCollector("mysqld_exporter"))
 }
 
-func filter(filters map[string]bool, name string, flag bool) bool {
-	if len(filters) > 0 {
-		return flag && filters[name]
-	}
-	return flag
-}
-
-func handler(w http.ResponseWriter, r *http.Request) {
-	var filters map[string]bool
+func newHandler(scrapers []collector.Scraper) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		filteredScrapers := scrapers
 		params := r.URL.Query()["collect[]"]
 		log.Debugln("collect query:", params)
 
+		// Check if we have some "collect[]" query parameters.
 		if len(params) > 0 {
-		filters = make(map[string]bool)
+			filters := make(map[string]bool)
 			for _, param := range params {
 				filters[param] = true
 			}
-	}
 
-	collect := collector.Collect{
-		Processlist:             filter(filters, "info_schema.processlist", *collectProcesslist),
-		TableSchema:             filter(filters, "info_schema.tables", *collectTableSchema),
-		InnodbTablespaces:       filter(filters, "info_schema.innodb_tablespaces", *collectInnodbTablespaces),
-		InnodbMetrics:           filter(filters, "info_schema.innodb_metrics", *collectInnodbMetrics),
-		GlobalStatus:            filter(filters, "global_status", *collectGlobalStatus),
-		GlobalVariables:         filter(filters, "global_variables", *collectGlobalVariables),
-		SlaveStatus:             filter(filters, "slave_status", *collectSlaveStatus),
-		AutoIncrementColumns:    filter(filters, "auto_increment.columns", *collectAutoIncrementColumns),
-		BinlogSize:              filter(filters, "binlog_size", *collectBinlogSize),
-		PerfTableIOWaits:        filter(filters, "perf_schema.tableiowaits", *collectPerfTableIOWaits),
-		PerfIndexIOWaits:        filter(filters, "perf_schema.indexiowaits", *collectPerfIndexIOWaits),
-		PerfTableLockWaits:      filter(filters, "perf_schema.tablelocks", *collectPerfTableLockWaits),
-		PerfEventsStatements:    filter(filters, "perf_schema.eventsstatements", *collectPerfEventsStatements),
-		PerfEventsWaits:         filter(filters, "perf_schema.eventswaits", *collectPerfEventsWaits),
-		PerfFileEvents:          filter(filters, "perf_schema.file_events", *collectPerfFileEvents),
-		PerfFileInstances:       filter(filters, "perf_schema.file_instances", *collectPerfFileInstances),
-		PerfRepGroupMemberStats: filter(filters, "perf_schema.replication_group_member_stats", *collectPerfRepGroupMemberStats),
-		UserStat:                filter(filters, "info_schema.userstats", *collectUserStat),
-		ClientStat:              filter(filters, "info_schema.clientstats", *collectClientStat),
-		InnodbCmp:               filter(filters, "info_schema.innodbcmp", *collectInnodbCmp),
-		InnodbCmpMem:            filter(filters, "info_schema.innodbcmpmem", *collectInnodbCmpMem),
-		TableStat:               filter(filters, "info_schema.tablestats", *collectTableStat),
-		QueryResponseTime:       filter(filters, "info_schema.query_response_time", *collectQueryResponseTime),
-		EngineTokudbStatus:      filter(filters, "engine_tokudb_status", *collectEngineTokudbStatus),
-		EngineInnodbStatus:      filter(filters, "engine_innodb_status", *collectEngineInnodbStatus),
-		Heartbeat:               filter(filters, "heartbeat", *collectHeartbeat),
-		HeartbeatDatabase:       *collectHeartbeatDatabase,
-		HeartbeatTable:          *collectHeartbeatTable,
+			filteredScrapers = nil
+			for _, scraper := range scrapers {
+				if filters[scraper.Name()] {
+					filteredScrapers = append(filteredScrapers, scraper)
+				}
+			}
 		}
 
 		registry := prometheus.NewRegistry()
-	registry.MustRegister(collector.New(dsn, collect))
+		registry.MustRegister(collector.New(dsn, filteredScrapers))
 
 		gatherers := prometheus.Gatherers{
 			prometheus.DefaultGatherer,
@@ -232,8 +121,26 @@ func handler(w http.ResponseWriter, r *http.Request) {
 		h := promhttp.HandlerFor(gatherers, promhttp.HandlerOpts{})
 		h.ServeHTTP(w, r)
 	}
+}
 
 func main() {
+	// Generate ON/OFF flags for all scrapers.
+	scraperFlags := map[collector.Scraper]*bool{}
+	for scraper, enabledByDefault := range scrapers {
+		defaultOn := "false"
+		if enabledByDefault {
+			defaultOn = "true"
+		}
+
+		f := kingpin.Flag(
+			"collect."+scraper.Name(),
+			scraper.Help(),
+		).Default(defaultOn).Bool()
+
+		scraperFlags[scraper] = f
+	}
+
+	// Parse flags.
 	log.AddFlags(kingpin.CommandLine)
 	kingpin.Version(version.Print("mysqld_exporter"))
 	kingpin.HelpFlag.Short('h')
@@ -261,7 +168,16 @@ func main() {
 		}
 	}
 
-	http.HandleFunc(*metricPath, prometheus.InstrumentHandlerFunc("metrics", handler))
+	// Register only scrapers enabled by flag.
+	log.Infof("Enabled scrapers:")
+	enabledScrapers := []collector.Scraper{}
+	for scraper, enabled := range scraperFlags {
+		if *enabled {
+			log.Infof(" --collect.%s", scraper.Name())
+			enabledScrapers = append(enabledScrapers, scraper)
+		}
+	}
+	http.HandleFunc(*metricPath, prometheus.InstrumentHandlerFunc("metrics", newHandler(enabledScrapers)))
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		w.Write(landingPage)
 	})