refactor: configure ping for a target or per job

cmd/sql_exporter/main.go

@@ -39,6 +39,8 @@ var (
 
 func init() {
 	prometheus.MustRegister(version.NewCollector("sql_exporter"))
+	flag.BoolVar(&cfg.EnablePing, "config.enable-ping", true, "Enable ping for targets")
+	flag.StringVar(&cfg.DsnOverride, "config.data-source-name", "", "Data source name to override the value in the configuration file with")
 	flag.StringVar(&cfg.TargetLabel, "config.target-label", "target", "Target label name")
 }
 
@@ -47,7 +49,6 @@ func main() {
 		runtime.SetBlockProfileRate(1)
 		runtime.SetMutexProfileFraction(1)
 	}
-
 	flag.Parse()
 
 	promlogConfig := &promlog.Config{}
@@ -135,7 +136,7 @@ func reloadCollectors(e sql_exporter.Exporter) func(http.ResponseWriter, *http.R
 			klog.Warning("Reloading target collectors...")
 			// FIXME: Should be t.Collectors() instead of config.Collectors
 			target, err := sql_exporter.NewTarget("", currentConfig.Target.Name, string(currentConfig.Target.DSN),
-				exporterNewConfig.Target.Collectors(), nil, currentConfig.Globals)
+				exporterNewConfig.Target.Collectors(), nil, currentConfig.Globals, currentConfig.Target.EnablePing)
 			if err != nil {
 				klog.Errorf("Error recreating a target - %v", err)
 				http.Error(w, err.Error(), http.StatusInternalServerError)

config/config.go

@@ -19,12 +19,16 @@ import (
 	"k8s.io/klog/v2"
 )
 
+var (
+	EnablePing  bool
+	DsnOverride string
+	TargetLabel string
+)
+
 // MaxInt32 defines the maximum value of allowed integers
 // and serves to help us avoid overflow/wraparound issues.
 const MaxInt32 int = 1<<31 - 1
 
-var TargetLabel string
-
 // Load attempts to parse the given config file and return a Config object.
 func Load(configFile string) (*Config, error) {
 	klog.Infof("Loading configuration from %s", configFile)
@@ -204,10 +208,11 @@ func (g *GlobalConfig) UnmarshalYAML(unmarshal func(any) error) error {
 
 // TargetConfig defines a DSN and a set of collectors to be executed on it.
 type TargetConfig struct {
-	Name          string   `yaml:"name,omitempty"`   // name of the target
-	DSN           Secret   `yaml:"data_source_name"` // data source name to connect to
-	AwsSecretName string   `yaml:"aws_secret_name"`  // AWS secret name
-	CollectorRefs []string `yaml:"collectors"`       // names of collectors to execute on the target
+	Name          string   `yaml:"name,omitempty"`        // name of the target
+	DSN           Secret   `yaml:"data_source_name"`      // data source name to connect to
+	AwsSecretName string   `yaml:"aws_secret_name"`       // AWS secret name
+	CollectorRefs []string `yaml:"collectors"`            // names of collectors to execute on the target
+	EnablePing    *bool    `yaml:"enable_ping,omitempty"` // ping the target before executing the collectors
 
 	collectors []*CollectorConfig // resolved collector references
 
@@ -293,6 +298,8 @@ type JobConfig struct {
 
 	collectors []*CollectorConfig // resolved collector references
 
+	EnablePing *bool `yaml:"enable_ping,omitempty"` // ping the target before executing the collectors
+
 	// Catches all undefined fields and must be empty after parsing.
 	XXX map[string]any `yaml:",inline" json:"-"`
 }

exporter.go

@@ -3,7 +3,6 @@ package sql_exporter
 import (
 	"context"
 	"errors"
-	"flag"
 	"fmt"
 	"os"
 	"sync"
@@ -16,8 +15,6 @@ import (
 
 const envDsnOverride = "SQLEXPORTER_TARGET_DSN"
 
-var dsnOverride = flag.String("config.data-source-name", "", "Data source name to override the value in the configuration file with.")
-
 // Exporter is a prometheus.Gatherer that gathers SQL metrics from targets and merges them with the default registry.
 type Exporter interface {
 	prometheus.Gatherer
@@ -44,19 +41,23 @@ func NewExporter(configFile string) (Exporter, error) {
 	}
 
 	if val, ok := os.LookupEnv(envDsnOverride); ok {
-		*dsnOverride = val
+		config.DsnOverride = val
 	}
 	// Override the DSN if requested (and in single target mode).
-	if *dsnOverride != "" {
+	if config.DsnOverride != "" {
 		if len(c.Jobs) > 0 {
-			return nil, fmt.Errorf("the config.data-source-name flag (value %q) only applies in single target mode", *dsnOverride)
+			return nil, fmt.Errorf("the config.data-source-name flag (value %q) only applies in single target mode", config.DsnOverride)
 		}
-		c.Target.DSN = config.Secret(*dsnOverride)
+		c.Target.DSN = config.Secret(config.DsnOverride)
+	}
+
+	if c.Target.EnablePing == nil {
+		c.Target.EnablePing = &config.EnablePing
 	}
 
 	var targets []Target
 	if c.Target != nil {
-		target, err := NewTarget("", c.Target.Name, string(c.Target.DSN), c.Target.Collectors(), nil, c.Globals)
+		target, err := NewTarget("", c.Target.Name, string(c.Target.DSN), c.Target.Collectors(), nil, c.Globals, c.Target.EnablePing)
 		if err != nil {
 			return nil, err
 		}

job.go

@@ -28,6 +28,10 @@ func NewJob(jc *config.JobConfig, gc *config.GlobalConfig) (Job, errors.WithCont
 		logContext: fmt.Sprintf("job=%q", jc.Name),
 	}
 
+	if jc.EnablePing == nil {
+		jc.EnablePing = &config.EnablePing
+	}
+
 	for _, sc := range jc.StaticConfigs {
 		for tname, dsn := range sc.Targets {
 			constLabels := prometheus.Labels{
@@ -41,7 +45,7 @@ func NewJob(jc *config.JobConfig, gc *config.GlobalConfig) (Job, errors.WithCont
 				}
 				constLabels[name] = value
 			}
-			t, err := NewTarget(j.logContext, tname, string(dsn), jc.Collectors(), constLabels, gc)
+			t, err := NewTarget(j.logContext, tname, string(dsn), jc.Collectors(), constLabels, gc, jc.EnablePing)
 			if err != nil {
 				return nil, err
 			}

target.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
-	"flag"
 	"fmt"
 	"sort"
 	"sync"
@@ -17,8 +16,6 @@ import (
 	"google.golang.org/protobuf/proto"
 )
 
-var enablePing = flag.Bool("config.enable-ping", true, "Enable ping for targets")
-
 const (
 	// Capacity for the channel to collect metrics.
 	capMetricChan = 1000
@@ -46,14 +43,15 @@ type target struct {
 	upDesc             MetricDesc
 	scrapeDurationDesc MetricDesc
 	logContext         string
+	enablePing         *bool
 
 	conn *sql.DB
 }
 
 // NewTarget returns a new Target with the given target name, data source name, collectors and constant labels.
 // An empty target name means the exporter is running in single target mode: no synthetic metrics will be exported.
 func NewTarget(
-	logContext, tname, dsn string, ccs []*config.CollectorConfig, constLabels prometheus.Labels, gc *config.GlobalConfig) (
+	logContext, tname, dsn string, ccs []*config.CollectorConfig, constLabels prometheus.Labels, gc *config.GlobalConfig, ep *bool) (
 	Target, errors.WithContext,
 ) {
 
@@ -93,6 +91,7 @@ func NewTarget(
 		upDesc:             upDesc,
 		scrapeDurationDesc: scrapeDurationDesc,
 		logContext:         logContext,
+		enablePing:         ep,
 	}
 	return &t, nil
 }
@@ -154,7 +153,7 @@ func (t *target) ping(ctx context.Context) errors.WithContext {
 	// If we have a handle and the context is not closed, test whether the database is up.
 	// FIXME: we ping the database during each request even with cacheCollector. It leads
 	// to additional charges for paid database services.
-	if t.conn != nil && ctx.Err() == nil && *enablePing {
+	if t.conn != nil && ctx.Err() == nil && *t.enablePing {
 		var err error
 		// Ping up to max_connections + 1 times as long as the returned error is driver.ErrBadConn, to purge the connection
 		// pool of bad connections. This might happen if the previous scrape timed out and in-flight queries got canceled.
@@ -181,3 +180,8 @@ func boolToFloat64(value bool) float64 {
 	}
 	return 0.0
 }
+
+// OfBool returns bool address.
+func OfBool(i bool) *bool {
+	return &i
+}