Add the instance struct to handle connections (#859)

The intent is to use the instance struct to hold the connection
to the database as well as metadata about the instance:
- version
- flavor (mariadb or mysql)

Change is similar to prometheus-community/postgres_exporter#785

Signed-off-by: Vlad Gusev <vlad.esten@gmail.com>

collector/binlog.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"fmt"
 	"strconv"
 	"strings"
@@ -72,8 +71,9 @@ func (ScrapeBinlogSize) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeBinlogSize) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeBinlogSize) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var logBin uint8
+	db := instance.getDB()
 	err := db.QueryRowContext(ctx, logbinQuery).Scan(&logBin)
 	if err != nil {
 		return err

collector/binlog_test.go

@@ -31,6 +31,8 @@ func TestScrapeBinlogSize(t *testing.T) {
 	}
 	defer db.Close()
 
+	inst := &instance{db: db}
+
 	mock.ExpectQuery(logbinQuery).WillReturnRows(sqlmock.NewRows([]string{""}).AddRow(1))
 
 	columns := []string{"Log_name", "File_size"}
@@ -42,7 +44,7 @@ func TestScrapeBinlogSize(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeBinlogSize{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeBinlogSize{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/engine_innodb.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"regexp"
 	"strconv"
 	"strings"
@@ -52,7 +51,8 @@ func (ScrapeEngineInnodbStatus) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeEngineInnodbStatus) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeEngineInnodbStatus) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	rows, err := db.QueryContext(ctx, engineInnodbStatusQuery)
 	if err != nil {
 		return err

collector/engine_innodb_test.go

@@ -152,10 +152,10 @@ END OF INNODB MONITOR OUTPUT
 	rows := sqlmock.NewRows(columns).AddRow("InnoDB", "", sample)
 
 	mock.ExpectQuery(sanitizeQuery(engineInnodbStatusQuery)).WillReturnRows(rows)
-
+	inst := &instance{db: db}
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeEngineInnodbStatus{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeEngineInnodbStatus{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/engine_tokudb.go

@@ -50,7 +50,8 @@ func (ScrapeEngineTokudbStatus) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeEngineTokudbStatus) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeEngineTokudbStatus) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	tokudbRows, err := db.QueryContext(ctx, engineTokudbStatusQuery)
 	if err != nil {
 		return err

collector/engine_tokudb_test.go

@@ -46,6 +46,7 @@ func TestScrapeEngineTokudbStatus(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"Type", "Name", "Status"}
 	rows := sqlmock.NewRows(columns).
@@ -59,7 +60,7 @@ func TestScrapeEngineTokudbStatus(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeEngineTokudbStatus{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeEngineTokudbStatus{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/exporter.go

@@ -15,10 +15,7 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"fmt"
-	"regexp"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -38,18 +35,12 @@ const (
 
 // SQL queries and parameters.
 const (
-	versionQuery = `SELECT @@version`
-
 	// System variable params formatting.
 	// See: https://github.com/go-sql-driver/mysql#system-variables
 	sessionSettingsParam = `log_slow_filter=%27tmp_table_on_disk,filesort_on_disk%27`
 	timeoutParam         = `lock_wait_timeout=%d`
 )
 
-var (
-	versionRE = regexp.MustCompile(`^\d+\.\d+`)
-)
-
 // Tunable flags.
 var (
 	exporterLockTimeout = kingpin.Flag(
@@ -92,6 +83,7 @@ type Exporter struct {
 	logger   log.Logger
 	dsn      string
 	scrapers []Scraper
+	instance *instance
 }
 
 // New returns a new MySQL exporter for the provided DSN.
@@ -135,27 +127,23 @@ func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
 func (e *Exporter) scrape(ctx context.Context, ch chan<- prometheus.Metric) float64 {
 	var err error
 	scrapeTime := time.Now()
-	db, err := sql.Open("mysql", e.dsn)
+	instance, err := newInstance(e.dsn)
 	if err != nil {
 		level.Error(e.logger).Log("msg", "Error opening connection to database", "err", err)
 		return 0.0
 	}
-	defer db.Close()
+	defer instance.Close()
+	e.instance = instance
 
-	// By design exporter should use maximum one connection per request.
+	if err := instance.Ping(); err != nil {
-	db.SetMaxOpenConns(1)
-	db.SetMaxIdleConns(1)
-	// Set max lifetime for a connection.
-	db.SetConnMaxLifetime(1 * time.Minute)
-
-	if err := db.PingContext(ctx); err != nil {
 		level.Error(e.logger).Log("msg", "Error pinging mysqld", "err", err)
 		return 0.0
 	}
 
 	ch <- prometheus.MustNewConstMetric(mysqlScrapeDurationSeconds, prometheus.GaugeValue, time.Since(scrapeTime).Seconds(), "connection")
 
-	version := getMySQLVersion(db, e.logger)
+	version := instance.versionMajorMinor
+
 	var wg sync.WaitGroup
 	defer wg.Wait()
 	for _, scraper := range e.scrapers {
@@ -169,7 +157,7 @@ func (e *Exporter) scrape(ctx context.Context, ch chan<- prometheus.Metric) floa
 			label := "collect." + scraper.Name()
 			scrapeTime := time.Now()
 			collectorSuccess := 1.0
-			if err := scraper.Scrape(ctx, db, ch, log.With(e.logger, "scraper", scraper.Name())); err != nil {
+			if err := scraper.Scrape(ctx, instance, ch, log.With(e.logger, "scraper", scraper.Name())); err != nil {
 				level.Error(e.logger).Log("msg", "Error from scraper", "scraper", scraper.Name(), "target", e.getTargetFromDsn(), "err", err)
 				collectorSuccess = 0.0
 			}
@@ -189,19 +177,3 @@ func (e *Exporter) getTargetFromDsn() string {
 	}
 	return dsnConfig.Addr
 }
-
-func getMySQLVersion(db *sql.DB, logger log.Logger) float64 {
-	var versionStr string
-	var versionNum float64
-	if err := db.QueryRow(versionQuery).Scan(&versionStr); err == nil {
-		versionNum, _ = strconv.ParseFloat(versionRE.FindString(versionStr), 64)
-	} else {
-		level.Debug(logger).Log("msg", "Error querying version", "err", err)
-	}
-	// If we can't match/parse the version, set it some big value that matches all versions.
-	if versionNum == 0 {
-		level.Debug(logger).Log("msg", "Error parsing version string", "version", versionStr)
-		versionNum = 999
-	}
-	return versionNum
-}

collector/exporter_test.go

@@ -15,12 +15,9 @@ package collector
 
 import (
 	"context"
-	"database/sql"
-	"os"
 	"testing"
 
 	"github.com/go-kit/log"
-	"github.com/go-kit/log/level"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
 	"github.com/smartystreets/goconvey/convey"
@@ -68,20 +65,3 @@ func TestExporter(t *testing.T) {
 		}
 	})
 }
-
-func TestGetMySQLVersion(t *testing.T) {
-	if testing.Short() {
-		t.Skip("-short is passed, skipping test")
-	}
-
-	logger := log.NewLogfmtLogger(os.Stderr)
-	logger = level.NewFilter(logger, level.AllowDebug())
-
-	convey.Convey("Version parsing", t, func() {
-		db, err := sql.Open("mysql", dsn)
-		convey.So(err, convey.ShouldBeNil)
-		defer db.Close()
-
-		convey.So(getMySQLVersion(db, logger), convey.ShouldBeBetweenOrEqual, 5.6, 12.0)
-	})
-}

collector/global_status.go

@@ -99,7 +99,8 @@ func (ScrapeGlobalStatus) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeGlobalStatus) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeGlobalStatus) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	globalStatusRows, err := db.QueryContext(ctx, globalStatusQuery)
 	if err != nil {
 		return err

collector/global_status_test.go

@@ -30,6 +30,7 @@ func TestScrapeGlobalStatus(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"Variable_name", "Value"}
 	rows := sqlmock.NewRows(columns).
@@ -63,7 +64,7 @@ func TestScrapeGlobalStatus(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeGlobalStatus{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeGlobalStatus{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/global_variables.go

@@ -138,7 +138,8 @@ func (ScrapeGlobalVariables) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeGlobalVariables) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeGlobalVariables) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	globalVariablesRows, err := db.QueryContext(ctx, globalVariablesQuery)
 	if err != nil {
 		return err

collector/global_variables_test.go

@@ -30,6 +30,7 @@ func TestScrapeGlobalVariables(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"Variable_name", "Value"}
 	rows := sqlmock.NewRows(columns).
@@ -52,7 +53,7 @@ func TestScrapeGlobalVariables(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeGlobalVariables{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeGlobalVariables{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/heartbeat.go

@@ -100,7 +100,8 @@ func nowExpr() string {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeHeartbeat) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeHeartbeat) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	query := fmt.Sprintf(heartbeatQuery, nowExpr(), *collectHeartbeatDatabase, *collectHeartbeatTable)
 	heartbeatRows, err := db.QueryContext(ctx, query)
 	if err != nil {

collector/heartbeat_test.go

@@ -65,6 +65,7 @@ func TestScrapeHeartbeat(t *testing.T) {
 				t.Fatalf("error opening a stub database connection: %s", err)
 			}
 			defer db.Close()
+			inst := &instance{db: db}
 
 			rows := sqlmock.NewRows(tt.Columns).
 				AddRow("1487597613.001320", "1487598113.448042", 1)
@@ -72,7 +73,7 @@ func TestScrapeHeartbeat(t *testing.T) {
 
 			ch := make(chan prometheus.Metric)
 			go func() {
-				if err = (ScrapeHeartbeat{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+				if err = (ScrapeHeartbeat{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 					t.Errorf("error calling function on test: %s", err)
 				}
 				close(ch)

collector/info_schema_auto_increment.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -70,7 +69,8 @@ func (ScrapeAutoIncrementColumns) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeAutoIncrementColumns) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeAutoIncrementColumns) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	autoIncrementRows, err := db.QueryContext(ctx, infoSchemaAutoIncrementQuery)
 	if err != nil {
 		return err

collector/info_schema_clientstats.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"fmt"
 	"strings"
 
@@ -161,8 +160,9 @@ func (ScrapeClientStat) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeClientStat) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeClientStat) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var varName, varVal string
+	db := instance.getDB()
 	err := db.QueryRowContext(ctx, userstatCheckQuery).Scan(&varName, &varVal)
 	if err != nil {
 		level.Debug(logger).Log("msg", "Detailed client stats are not available.")

collector/info_schema_clientstats_test.go

@@ -30,6 +30,7 @@ func TestScrapeClientStat(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	mock.ExpectQuery(sanitizeQuery(userstatCheckQuery)).WillReturnRows(sqlmock.NewRows([]string{"Variable_name", "Value"}).
 		AddRow("userstat", "ON"))
@@ -41,7 +42,7 @@ func TestScrapeClientStat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeClientStat{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeClientStat{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_innodb_cmp.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -77,7 +76,8 @@ func (ScrapeInnodbCmp) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeInnodbCmp) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeInnodbCmp) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	informationSchemaInnodbCmpRows, err := db.QueryContext(ctx, innodbCmpQuery)
 	if err != nil {
 		return err

collector/info_schema_innodb_cmp_test.go

@@ -30,6 +30,7 @@ func TestScrapeInnodbCmp(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"page_size", "compress_ops", "compress_ops_ok", "compress_time", "uncompress_ops", "uncompress_time"}
 	rows := sqlmock.NewRows(columns).
@@ -38,7 +39,7 @@ func TestScrapeInnodbCmp(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeInnodbCmp{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeInnodbCmp{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_innodb_cmpmem.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -72,7 +71,8 @@ func (ScrapeInnodbCmpMem) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeInnodbCmpMem) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeInnodbCmpMem) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	informationSchemaInnodbCmpMemRows, err := db.QueryContext(ctx, innodbCmpMemQuery)
 	if err != nil {
 		return err

collector/info_schema_innodb_cmpmem_test.go

@@ -30,6 +30,7 @@ func TestScrapeInnodbCmpMem(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"page_size", "buffer_pool", "pages_used", "pages_free", "relocation_ops", "relocation_time"}
 	rows := sqlmock.NewRows(columns).
@@ -38,7 +39,7 @@ func TestScrapeInnodbCmpMem(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeInnodbCmpMem{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeInnodbCmpMem{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_innodb_metrics.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"errors"
 	"fmt"
 	"regexp"
@@ -93,10 +92,11 @@ func (ScrapeInnodbMetrics) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeInnodbMetrics) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeInnodbMetrics) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var enabledColumnName string
 	var query string
 
+	db := instance.getDB()
 	err := db.QueryRowContext(ctx, infoSchemaInnodbMetricsEnabledColumnQuery).Scan(&enabledColumnName)
 	if err != nil {
 		return err

collector/info_schema_innodb_metrics_test.go

@@ -31,6 +31,7 @@ func TestScrapeInnodbMetrics(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	enabledColumnName := []string{"COLUMN_NAME"}
 	rows := sqlmock.NewRows(enabledColumnName).
@@ -53,7 +54,7 @@ func TestScrapeInnodbMetrics(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeInnodbMetrics{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeInnodbMetrics{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_innodb_sys_tablespaces.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"errors"
 	"fmt"
 
@@ -85,9 +84,10 @@ func (ScrapeInfoSchemaInnodbTablespaces) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeInfoSchemaInnodbTablespaces) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeInfoSchemaInnodbTablespaces) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var tablespacesTablename string
 	var query string
+	db := instance.getDB()
 	err := db.QueryRowContext(ctx, innodbTablespacesTablenameQuery).Scan(&tablespacesTablename)
 	if err != nil {
 		return err

collector/info_schema_innodb_sys_tablespaces_test.go

@@ -31,6 +31,7 @@ func TestScrapeInfoSchemaInnodbTablespaces(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"TABLE_NAME"}
 	rows := sqlmock.NewRows(columns).
@@ -47,7 +48,7 @@ func TestScrapeInfoSchemaInnodbTablespaces(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeInfoSchemaInnodbTablespaces{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeInfoSchemaInnodbTablespaces{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_processlist.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"fmt"
 	"reflect"
 	"sort"
@@ -97,11 +96,12 @@ func (ScrapeProcesslist) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeProcesslist) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeProcesslist) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	processQuery := fmt.Sprintf(
 		infoSchemaProcesslistQuery,
 		*processlistMinTime,
 	)
+	db := instance.getDB()
 	processlistRows, err := db.QueryContext(ctx, processQuery)
 	if err != nil {
 		return err

collector/info_schema_processlist_test.go

@@ -40,6 +40,7 @@ func TestScrapeProcesslist(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	query := fmt.Sprintf(infoSchemaProcesslistQuery, 0)
 	columns := []string{"user", "host", "command", "state", "processes", "seconds"}
@@ -56,7 +57,7 @@ func TestScrapeProcesslist(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeProcesslist{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeProcesslist{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_query_response_time.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"strconv"
 	"strings"
 
@@ -56,7 +55,8 @@ var (
 	}
 )
 
-func processQueryResponseTimeTable(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, query string, i int) error {
+func processQueryResponseTimeTable(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, query string, i int) error {
+	db := instance.getDB()
 	queryDistributionRows, err := db.QueryContext(ctx, query)
 	if err != nil {
 		return err
@@ -119,8 +119,9 @@ func (ScrapeQueryResponseTime) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeQueryResponseTime) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeQueryResponseTime) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var queryStats uint8
+	db := instance.getDB()
 	err := db.QueryRowContext(ctx, queryResponseCheckQuery).Scan(&queryStats)
 	if err != nil {
 		level.Debug(logger).Log("msg", "Query response time distribution is not available.")
@@ -132,7 +133,7 @@ func (ScrapeQueryResponseTime) Scrape(ctx context.Context, db *sql.DB, ch chan<-
 	}
 
 	for i, query := range queryResponseTimeQueries {
-		err := processQueryResponseTimeTable(ctx, db, ch, query, i)
+		err := processQueryResponseTimeTable(ctx, instance, ch, query, i)
 		// The first query should not fail if query_response_time_stats is ON,
 		// unlike the other two when the read/write tables exist only with Percona Server 5.6/5.7.
 		if i == 0 && err != nil {

collector/info_schema_query_response_time_test.go

@@ -30,6 +30,7 @@ func TestScrapeQueryResponseTime(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	mock.ExpectQuery(queryResponseCheckQuery).WillReturnRows(sqlmock.NewRows([]string{""}).AddRow(1))
 
@@ -52,7 +53,7 @@ func TestScrapeQueryResponseTime(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeQueryResponseTime{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeQueryResponseTime{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_replica_host.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
@@ -84,7 +83,8 @@ func (ScrapeReplicaHost) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeReplicaHost) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeReplicaHost) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	replicaHostRows, err := db.QueryContext(ctx, replicaHostQuery)
 	if err != nil {
 		if mysqlErr, ok := err.(*MySQL.MySQLError); ok { // Now the error number is accessible directly

collector/info_schema_replica_host_test.go

@@ -30,6 +30,7 @@ func TestScrapeReplicaHost(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"SERVER_ID", "ROLE", "CPU", "MASTER_SLAVE_LATENCY_IN_MICROSECONDS", "REPLICA_LAG_IN_MILLISECONDS", "LOG_STREAM_SPEED_IN_KiB_PER_SECOND", "CURRENT_REPLAY_LATENCY_IN_MICROSECONDS"}
 	rows := sqlmock.NewRows(columns).
@@ -39,7 +40,7 @@ func TestScrapeReplicaHost(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeReplicaHost{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeReplicaHost{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_schemastats.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
@@ -72,9 +71,10 @@ func (ScrapeSchemaStat) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeSchemaStat) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeSchemaStat) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var varName, varVal string
 
+	db := instance.getDB()
 	err := db.QueryRowContext(ctx, userstatCheckQuery).Scan(&varName, &varVal)
 	if err != nil {
 		level.Debug(logger).Log("msg", "Detailed schema stats are not available.")

collector/info_schema_schemastats_test.go

@@ -29,6 +29,7 @@ func TestScrapeSchemaStat(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	mock.ExpectQuery(sanitizeQuery(userstatCheckQuery)).WillReturnRows(sqlmock.NewRows([]string{"Variable_name", "Value"}).
 		AddRow("userstat", "ON"))
@@ -41,7 +42,7 @@ func TestScrapeSchemaStat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeSchemaStat{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeSchemaStat{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_tables.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"fmt"
 	"strings"
 
@@ -97,8 +96,9 @@ func (ScrapeTableSchema) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeTableSchema) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeTableSchema) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var dbList []string
+	db := instance.getDB()
 	if *tableSchemaDatabases == "*" {
 		dbListRows, err := db.QueryContext(ctx, dbListQuery)
 		if err != nil {

collector/info_schema_tablestats.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
@@ -72,8 +71,9 @@ func (ScrapeTableStat) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeTableStat) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeTableStat) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var varName, varVal string
+	db := instance.getDB()
 	err := db.QueryRowContext(ctx, userstatCheckQuery).Scan(&varName, &varVal)
 	if err != nil {
 		level.Debug(logger).Log("msg", "Detailed table stats are not available.")

collector/info_schema_tablestats_test.go

@@ -29,6 +29,7 @@ func TestScrapeTableStat(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	mock.ExpectQuery(sanitizeQuery(userstatCheckQuery)).WillReturnRows(sqlmock.NewRows([]string{"Variable_name", "Value"}).
 		AddRow("userstat", "ON"))
@@ -42,7 +43,7 @@ func TestScrapeTableStat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeTableStat{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeTableStat{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/info_schema_userstats.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"fmt"
 	"strings"
 
@@ -157,8 +156,9 @@ func (ScrapeUserStat) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeUserStat) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeUserStat) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var varName, varVal string
+	db := instance.getDB()
 	err := db.QueryRowContext(ctx, userstatCheckQuery).Scan(&varName, &varVal)
 	if err != nil {
 		level.Debug(logger).Log("msg", "Detailed user stats are not available.")

collector/info_schema_userstats_test.go

@@ -30,6 +30,7 @@ func TestScrapeUserStat(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	mock.ExpectQuery(sanitizeQuery(userstatCheckQuery)).WillReturnRows(sqlmock.NewRows([]string{"Variable_name", "Value"}).
 		AddRow("userstat", "ON"))
@@ -41,7 +42,7 @@ func TestScrapeUserStat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeUserStat{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeUserStat{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/instance.go

@@ -0,0 +1,114 @@
+// Copyright 2024 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"database/sql"
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/blang/semver/v4"
+)
+
+const (
+	FlavorMySQL   = "mysql"
+	FlavorMariaDB = "mariadb"
+)
+
+type instance struct {
+	db                *sql.DB
+	flavor            string
+	version           semver.Version
+	versionMajorMinor float64
+}
+
+func newInstance(dsn string) (*instance, error) {
+	i := &instance{}
+	db, err := sql.Open("mysql", dsn)
+	if err != nil {
+		return nil, err
+	}
+	db.SetMaxOpenConns(1)
+	db.SetMaxIdleConns(1)
+	i.db = db
+
+	version, versionString, err := queryVersion(db)
+	if err != nil {
+		db.Close()
+		return nil, err
+	}
+
+	i.version = version
+
+	versionMajorMinor, err := strconv.ParseFloat(fmt.Sprintf("%d.%d", i.version.Major, i.version.Minor), 64)
+	if err != nil {
+		db.Close()
+		return nil, err
+	}
+
+	i.versionMajorMinor = versionMajorMinor
+
+	if strings.Contains(strings.ToLower(versionString), "mariadb") {
+		i.flavor = FlavorMariaDB
+	} else {
+		i.flavor = FlavorMySQL
+	}
+
+	return i, nil
+}
+
+func (i *instance) getDB() *sql.DB {
+	return i.db
+}
+
+func (i *instance) Close() error {
+	return i.db.Close()
+}
+
+// Ping checks connection availability and possibly invalidates the connection if it fails.
+func (i *instance) Ping() error {
+	if err := i.db.Ping(); err != nil {
+		if cerr := i.Close(); cerr != nil {
+			return err
+		}
+		return err
+	}
+	return nil
+}
+
+// The result of SELECT version() is something like:
+// for MariaDB: "10.5.17-MariaDB-1:10.5.17+maria~ubu2004-log"
+// for MySQL: "8.0.36-28.1"
+var versionRegex = regexp.MustCompile(`^((\d+)(\.\d+)(\.\d+))`)
+
+func queryVersion(db *sql.DB) (semver.Version, string, error) {
+	var version string
+	err := db.QueryRow("SELECT @@version;").Scan(&version)
+	if err != nil {
+		return semver.Version{}, version, err
+	}
+
+	matches := versionRegex.FindStringSubmatch(version)
+	if len(matches) > 1 {
+		parsedVersion, err := semver.ParseTolerant(matches[1])
+		if err != nil {
+			return semver.Version{}, version, fmt.Errorf("could not parse version from %q", matches[1])
+		}
+		return parsedVersion, version, nil
+	}
+
+	return semver.Version{}, version, fmt.Errorf("could not parse version from %q", version)
+}

collector/mysql_user.go

@@ -120,7 +120,8 @@ func (ScrapeUser) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeUser) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeUser) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	var (
 		userRows *sql.Rows
 		err      error

collector/perf_schema_events_statements.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"fmt"
 
 	"github.com/alecthomas/kingpin/v2"
@@ -168,13 +167,14 @@ func (ScrapePerfEventsStatements) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfEventsStatements) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfEventsStatements) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	perfQuery := fmt.Sprintf(
 		perfEventsStatementsQuery,
 		*perfEventsStatementsDigestTextLimit,
 		*perfEventsStatementsTimeLimit,
 		*perfEventsStatementsLimit,
 	)
+	db := instance.getDB()
 	// Timers here are returned in picoseconds.
 	perfSchemaEventsStatementsRows, err := db.QueryContext(ctx, perfQuery)
 	if err != nil {

collector/perf_schema_events_statements_sum.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -177,7 +176,8 @@ func (ScrapePerfEventsStatementsSum) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfEventsStatementsSum) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfEventsStatementsSum) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	// Timers here are returned in picoseconds.
 	perfEventsStatementsSumRows, err := db.QueryContext(ctx, perfEventsStatementsSumQuery)
 	if err != nil {

collector/perf_schema_events_waits.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -61,7 +60,8 @@ func (ScrapePerfEventsWaits) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfEventsWaits) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfEventsWaits) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	// Timers here are returned in picoseconds.
 	perfSchemaEventsWaitsRows, err := db.QueryContext(ctx, perfEventsWaitsQuery)
 	if err != nil {

collector/perf_schema_file_events.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -70,7 +69,8 @@ func (ScrapePerfFileEvents) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfFileEvents) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfFileEvents) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	// Timers here are returned in picoseconds.
 	perfSchemaFileEventsRows, err := db.QueryContext(ctx, perfFileEventsQuery)
 	if err != nil {

collector/perf_schema_file_instances.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"strings"
 
 	"github.com/alecthomas/kingpin/v2"
@@ -80,7 +79,8 @@ func (ScrapePerfFileInstances) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfFileInstances) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfFileInstances) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	// Timers here are returned in picoseconds.
 	perfSchemaFileInstancesRows, err := db.QueryContext(ctx, perfFileInstancesQuery, *performanceSchemaFileInstancesFilter)
 	if err != nil {

collector/perf_schema_file_instances_test.go

@@ -37,6 +37,7 @@ func TestScrapePerfFileInstances(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"FILE_NAME", "EVENT_NAME", "COUNT_READ", "COUNT_WRITE", "SUM_NUMBER_OF_BYTES_READ", "SUM_NUMBER_OF_BYTES_WRITE"}
 
@@ -48,7 +49,7 @@ func TestScrapePerfFileInstances(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapePerfFileInstances{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapePerfFileInstances{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			panic(fmt.Sprintf("error calling function on test: %s", err))
 		}
 		close(ch)

collector/perf_schema_index_io_waits.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -64,7 +63,8 @@ func (ScrapePerfIndexIOWaits) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfIndexIOWaits) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfIndexIOWaits) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	perfSchemaIndexWaitsRows, err := db.QueryContext(ctx, perfIndexIOWaitsQuery)
 	if err != nil {
 		return err

collector/perf_schema_index_io_waits_test.go

@@ -30,6 +30,7 @@ func TestScrapePerfIndexIOWaits(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"OBJECT_SCHEMA", "OBJECT_NAME", "INDEX_NAME", "COUNT_FETCH", "COUNT_INSERT", "COUNT_UPDATE", "COUNT_DELETE", "SUM_TIMER_FETCH", "SUM_TIMER_INSERT", "SUM_TIMER_UPDATE", "SUM_TIMER_DELETE"}
 	rows := sqlmock.NewRows(columns).
@@ -40,7 +41,7 @@ func TestScrapePerfIndexIOWaits(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapePerfIndexIOWaits{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapePerfIndexIOWaits{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/perf_schema_memory_events.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"strings"
 
 	"github.com/alecthomas/kingpin/v2"
@@ -79,7 +78,8 @@ func (ScrapePerfMemoryEvents) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfMemoryEvents) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfMemoryEvents) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	perfSchemaMemoryEventsRows, err := db.QueryContext(ctx, perfMemoryEventsQuery)
 	if err != nil {
 		return err

collector/perf_schema_memory_events_test.go

@@ -37,6 +37,7 @@ func TestScrapePerfMemoryEvents(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{
 		"EVENT_NAME",
@@ -54,7 +55,7 @@ func TestScrapePerfMemoryEvents(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapePerfMemoryEvents{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapePerfMemoryEvents{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			panic(fmt.Sprintf("error calling function on test: %s", err))
 		}
 		close(ch)

collector/perf_schema_replication_applier_status_by_worker.go

@@ -15,7 +15,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 	"time"
 
 	"github.com/go-kit/log"
@@ -101,7 +100,8 @@ func (ScrapePerfReplicationApplierStatsByWorker) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfReplicationApplierStatsByWorker) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfReplicationApplierStatsByWorker) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	perfReplicationApplierStatsByWorkerRows, err := db.QueryContext(ctx, perfReplicationApplierStatsByWorkerQuery)
 	if err != nil {
 		return err

collector/perf_schema_replication_applier_status_by_worker_test.go

@@ -31,6 +31,7 @@ func TestScrapePerfReplicationApplierStatsByWorker(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{
 		"CHANNEL_NAME",
@@ -54,7 +55,7 @@ func TestScrapePerfReplicationApplierStatsByWorker(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapePerfReplicationApplierStatsByWorker{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapePerfReplicationApplierStatsByWorker{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/perf_schema_replication_group_member_stats.go

@@ -79,7 +79,8 @@ func (ScrapePerfReplicationGroupMemberStats) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfReplicationGroupMemberStats) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfReplicationGroupMemberStats) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	rows, err := db.QueryContext(ctx, perfReplicationGroupMemberStatsQuery)
 	if err != nil {
 		return err

collector/perf_schema_replication_group_member_stats_test.go

@@ -30,6 +30,7 @@ func TestScrapePerfReplicationGroupMemberStats(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{
 		"CHANNEL_NAME",
@@ -66,7 +67,7 @@ func TestScrapePerfReplicationGroupMemberStats(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapePerfReplicationGroupMemberStats{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapePerfReplicationGroupMemberStats{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/perf_schema_replication_group_members.go

@@ -16,9 +16,10 @@ package collector
 import (
 	"context"
 	"database/sql"
+	"strings"
+
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
-	"strings"
 )
 
 const perfReplicationGroupMembersQuery = `
@@ -44,7 +45,8 @@ func (ScrapePerfReplicationGroupMembers) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfReplicationGroupMembers) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfReplicationGroupMembers) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	perfReplicationGroupMembersRows, err := db.QueryContext(ctx, perfReplicationGroupMembersQuery)
 	if err != nil {
 		return err

collector/perf_schema_replication_group_members_test.go

@@ -15,12 +15,13 @@ package collector
 
 import (
 	"context"
+	"testing"
+
 	"github.com/DATA-DOG/go-sqlmock"
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
 	dto "github.com/prometheus/client_model/go"
 	"github.com/smartystreets/goconvey/convey"
-	"testing"
 )
 
 func TestScrapePerfReplicationGroupMembers(t *testing.T) {
@@ -29,6 +30,7 @@ func TestScrapePerfReplicationGroupMembers(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{
 		"CHANNEL_NAME",
@@ -49,7 +51,7 @@ func TestScrapePerfReplicationGroupMembers(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapePerfReplicationGroupMembers{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapePerfReplicationGroupMembers{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)
@@ -82,6 +84,7 @@ func TestScrapePerfReplicationGroupMembersMySQL57(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{
 		"CHANNEL_NAME",
@@ -100,7 +103,7 @@ func TestScrapePerfReplicationGroupMembersMySQL57(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapePerfReplicationGroupMembers{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapePerfReplicationGroupMembers{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/perf_schema_table_io_waits.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -65,7 +64,8 @@ func (ScrapePerfTableIOWaits) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfTableIOWaits) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfTableIOWaits) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	perfSchemaTableWaitsRows, err := db.QueryContext(ctx, perfTableIOWaitsQuery)
 	if err != nil {
 		return err

collector/perf_schema_table_lock_waits.go

@@ -17,7 +17,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -94,7 +93,8 @@ func (ScrapePerfTableLockWaits) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapePerfTableLockWaits) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapePerfTableLockWaits) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	db := instance.getDB()
 	perfSchemaTableLockWaitsRows, err := db.QueryContext(ctx, perfTableLockWaitsQuery)
 	if err != nil {
 		return err

collector/scraper.go

@@ -15,7 +15,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	_ "github.com/go-sql-driver/mysql"
@@ -35,5 +34,5 @@ type Scraper interface {
 	Version() float64
 
 	// Scrape collects data from database connection and sends it over channel as prometheus metric.
-	Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error
+	Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error
 }

collector/slave_hosts.go

@@ -63,11 +63,12 @@ func (ScrapeSlaveHosts) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeSlaveHosts) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeSlaveHosts) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var (
 		slaveHostsRows *sql.Rows
 		err            error
 	)
+	db := instance.getDB()
 	// Try the both syntax for MySQL 8.0 and MySQL 8.4
 	if slaveHostsRows, err = db.QueryContext(ctx, slaveHostsQuery); err != nil {
 		if slaveHostsRows, err = db.QueryContext(ctx, showReplicasQuery); err != nil {

collector/slave_hosts_test.go

@@ -30,6 +30,7 @@ func TestScrapeSlaveHostsOldFormat(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"Server_id", "Host", "Port", "Rpl_recovery_rank", "Master_id"}
 	rows := sqlmock.NewRows(columns).
@@ -39,7 +40,7 @@ func TestScrapeSlaveHostsOldFormat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeSlaveHosts{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeSlaveHosts{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)
@@ -68,6 +69,7 @@ func TestScrapeSlaveHostsNewFormat(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"Server_id", "Host", "Port", "Master_id", "Slave_UUID"}
 	rows := sqlmock.NewRows(columns).
@@ -77,7 +79,7 @@ func TestScrapeSlaveHostsNewFormat(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeSlaveHosts{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeSlaveHosts{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)
@@ -106,6 +108,7 @@ func TestScrapeSlaveHostsWithoutSlaveUuid(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"Server_id", "Host", "Port", "Master_id"}
 	rows := sqlmock.NewRows(columns).
@@ -115,7 +118,7 @@ func TestScrapeSlaveHostsWithoutSlaveUuid(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeSlaveHosts{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeSlaveHosts{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/slave_status.go

@@ -69,11 +69,12 @@ func (ScrapeSlaveStatus) Version() float64 {
 }
 
 // Scrape collects data from database connection and sends it over channel as prometheus metric.
-func (ScrapeSlaveStatus) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeSlaveStatus) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
 	var (
 		slaveStatusRows *sql.Rows
 		err             error
 	)
+	db := instance.getDB()
 	// Try the both syntax for MySQL/Percona and MariaDB
 	for _, query := range slaveStatusQueries {
 		slaveStatusRows, err = db.QueryContext(ctx, query)

collector/slave_status_test.go

@@ -30,6 +30,7 @@ func TestScrapeSlaveStatus(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{"Master_Host", "Read_Master_Log_Pos", "Slave_IO_Running", "Slave_SQL_Running", "Seconds_Behind_Master"}
 	rows := sqlmock.NewRows(columns).
@@ -38,7 +39,7 @@ func TestScrapeSlaveStatus(t *testing.T) {
 
 	ch := make(chan prometheus.Metric)
 	go func() {
-		if err = (ScrapeSlaveStatus{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeSlaveStatus{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

collector/sys_user_summary.go

@@ -15,7 +15,6 @@ package collector
 
 import (
 	"context"
-	"database/sql"
 
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
@@ -99,7 +98,9 @@ func (ScrapeSysUserSummary) Version() float64 {
 }
 
 // Scrape the information from sys.user_summary, creating a metric for each value of each row, labeled with the user
-func (ScrapeSysUserSummary) Scrape(ctx context.Context, db *sql.DB, ch chan<- prometheus.Metric, logger log.Logger) error {
+func (ScrapeSysUserSummary) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+
+	db := instance.getDB()
 
 	userSummaryRows, err := db.QueryContext(ctx, sysUserSummaryQuery)
 	if err != nil {

collector/sys_user_summary_test.go

@@ -16,14 +16,15 @@ package collector
 import (
 	"context"
 	"database/sql/driver"
+	"regexp"
+	"strconv"
+	"testing"
+
 	"github.com/DATA-DOG/go-sqlmock"
 	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
 	dto "github.com/prometheus/client_model/go"
 	"github.com/smartystreets/goconvey/convey"
-	"regexp"
-	"strconv"
-	"testing"
 )
 
 func TestScrapeSysUserSummary(t *testing.T) {
@@ -33,6 +34,7 @@ func TestScrapeSysUserSummary(t *testing.T) {
 		t.Fatalf("error opening a stub database connection: %s", err)
 	}
 	defer db.Close()
+	inst := &instance{db: db}
 
 	columns := []string{
 		"user",
@@ -111,7 +113,7 @@ func TestScrapeSysUserSummary(t *testing.T) {
 	ch := make(chan prometheus.Metric)
 
 	go func() {
-		if err = (ScrapeSysUserSummary{}).Scrape(context.Background(), db, ch, log.NewNopLogger()); err != nil {
+		if err = (ScrapeSysUserSummary{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
 			t.Errorf("error calling function on test: %s", err)
 		}
 		close(ch)

go.mod

@@ -5,6 +5,7 @@ go 1.21
 require (
 	github.com/DATA-DOG/go-sqlmock v1.5.2
 	github.com/alecthomas/kingpin/v2 v2.4.0
+	github.com/blang/semver/v4 v4.0.0
 	github.com/go-kit/log v0.2.1
 	github.com/go-sql-driver/mysql v1.8.1
 	github.com/google/go-cmp v0.6.0

go.sum

@@ -8,6 +8,8 @@ github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137 h1:s6gZFSlWYmbqAu
 github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/blang/semver/v4 v4.0.0 h1:1PFHFE6yCCTv8C1TeyNNarDzntLi7wMI5i/pzqYIsAM=
+github.com/blang/semver/v4 v4.0.0/go.mod h1:IbckMUScFkM3pff0VJDNKRiT6TG/YpiHIM2yvyW5YoQ=
 github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
 github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/coreos/go-systemd/v22 v22.5.0 h1:RrqgGjYQKalulkV8NGVIfkXQf6YYmOyiJKk8iXXhfZs=