feat: reorganize code to remove the main package

cmd/postgres_exporter/main.go

@@ -1,4 +1,4 @@
-// Copyright 2021 The Prometheus Authors
+// Copyright 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
@@ -23,6 +23,7 @@ import (
 	"github.com/alecthomas/kingpin/v2"
 	"github.com/prometheus-community/postgres_exporter/collector"
 	"github.com/prometheus-community/postgres_exporter/config"
+	"github.com/prometheus-community/postgres_exporter/exporter"
 	"github.com/prometheus/client_golang/prometheus"
 	versioncollector "github.com/prometheus/client_golang/prometheus/collectors/version"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -54,20 +55,8 @@ var (
 	logger                 = promslog.NewNopLogger()
 )
 
-// Metric name parts.
-const (
-	// Namespace for all metrics.
-	namespace = "pg"
-	// Subsystems.
-	exporter = "exporter"
-	// The name of the exporter.
-	exporterName = "postgres_exporter"
-	// Metric label used for static string data thats handy to send to Prometheus
-	// e.g. version
-	staticLabelName = "static"
-	// Metric label used for server identification.
-	serverLabelName = "server"
-)
+// The name of the exporter.
+const exporterName = "postgres_exporter"
 
 func main() {
 	kingpin.Version(version.Print(exporterName))
@@ -78,7 +67,7 @@ func main() {
 	logger = promslog.New(promslogConfig)
 
 	if *onlyDumpMaps {
-		dumpMaps()
+		exporter.DumpMaps()
 		return
 	}
 
@@ -87,7 +76,7 @@ func main() {
 		logger.Warn("Error loading config", "err", err)
 	}
 
-	dsns, err := getDataSources()
+	dsns, err := exporter.GetDataSources()
 	if err != nil {
 		logger.Error("Failed reading data sources", "err", err.Error())
 		os.Exit(1)
@@ -108,19 +97,21 @@ func main() {
 		logger.Warn("Constant labels on all metrics is DEPRECATED")
 	}
 
-	opts := []ExporterOpt{
-		DisableDefaultMetrics(*disableDefaultMetrics),
-		DisableSettingsMetrics(*disableSettingsMetrics),
-		AutoDiscoverDatabases(*autoDiscoverDatabases),
-		WithUserQueriesPath(*queriesPath),
-		WithConstantLabels(*constantLabelsList),
-		ExcludeDatabases(excludedDatabases),
-		IncludeDatabases(*includeDatabases),
+	opts := []exporter.ExporterOpt{
+		exporter.DisableDefaultMetrics(*disableDefaultMetrics),
+		exporter.DisableSettingsMetrics(*disableSettingsMetrics),
+		exporter.AutoDiscoverDatabases(*autoDiscoverDatabases),
+		exporter.WithUserQueriesPath(*queriesPath),
+		exporter.WithConstantLabels(*constantLabelsList),
+		exporter.ExcludeDatabases(excludedDatabases),
+		exporter.IncludeDatabases(*includeDatabases),
+		exporter.WithMetricPrefix(*metricPrefix),
+		exporter.WithLogger(logger),
 	}
 
-	exporter := NewExporter(dsns, opts...)
+	exporter := exporter.NewExporter(dsns, opts...)
 	defer func() {
-		exporter.servers.Close()
+		exporter.CloseServers()
 	}()
 
 	prometheus.MustRegister(versioncollector.NewCollector(exporterName))

cmd/postgres_exporter/probe.go

@@ -20,6 +20,7 @@ import (
 
 	"github.com/prometheus-community/postgres_exporter/collector"
 	"github.com/prometheus-community/postgres_exporter/config"
+	"github.com/prometheus-community/postgres_exporter/exporter"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
@@ -64,20 +65,22 @@ func handleProbe(logger *slog.Logger, excludeDatabases []string) http.HandlerFun
 
 		registry := prometheus.NewRegistry()
 
-		opts := []ExporterOpt{
-			DisableDefaultMetrics(*disableDefaultMetrics),
-			DisableSettingsMetrics(*disableSettingsMetrics),
-			AutoDiscoverDatabases(*autoDiscoverDatabases),
-			WithUserQueriesPath(*queriesPath),
-			WithConstantLabels(*constantLabelsList),
-			ExcludeDatabases(excludeDatabases),
-			IncludeDatabases(*includeDatabases),
+		opts := []exporter.ExporterOpt{
+			exporter.DisableDefaultMetrics(*disableDefaultMetrics),
+			exporter.DisableSettingsMetrics(*disableSettingsMetrics),
+			exporter.AutoDiscoverDatabases(*autoDiscoverDatabases),
+			exporter.WithUserQueriesPath(*queriesPath),
+			exporter.WithConstantLabels(*constantLabelsList),
+			exporter.ExcludeDatabases(excludeDatabases),
+			exporter.IncludeDatabases(*includeDatabases),
+			exporter.WithLogger(logger),
+			exporter.WithMetricPrefix(*metricPrefix),
 		}
 
 		dsns := []string{dsn.GetConnectionString()}
-		exporter := NewExporter(dsns, opts...)
+		exporter := exporter.NewExporter(dsns, opts...)
 		defer func() {
-			exporter.servers.Close()
+			exporter.CloseServers()
 		}()
 		registry.MustRegister(exporter)
 

cmd/postgres_exporter/datasource.go → exporter/datasource.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package exporter
 
 import (
 	"fmt"
@@ -39,19 +39,19 @@ func (e *Exporter) discoverDatabaseDSNs() []string {
 			var err error
 			dsnURI, err = url.Parse(dsn)
 			if err != nil {
-				logger.Error("Unable to parse DSN as URI", "dsn", loggableDSN(dsn), "err", err)
+				e.logger.Error("Unable to parse DSN as URI", "dsn", loggableDSN(dsn), "err", err)
 				continue
 			}
 		} else if connstringRe.MatchString(dsn) {
 			dsnConnstring = dsn
 		} else {
-			logger.Error("Unable to parse DSN as either URI or connstring", "dsn", loggableDSN(dsn))
+			e.logger.Error("Unable to parse DSN as either URI or connstring", "dsn", loggableDSN(dsn))
 			continue
 		}
 
 		server, err := e.servers.GetServer(dsn)
 		if err != nil {
-			logger.Error("Error opening connection to database", "dsn", loggableDSN(dsn), "err", err)
+			e.logger.Error("Error opening connection to database", "dsn", loggableDSN(dsn), "err", err)
 			continue
 		}
 		dsns[dsn] = struct{}{}
@@ -61,7 +61,7 @@ func (e *Exporter) discoverDatabaseDSNs() []string {
 
 		databaseNames, err := queryDatabases(server)
 		if err != nil {
-			logger.Error("Error querying databases", "dsn", loggableDSN(dsn), "err", err)
+			e.logger.Error("Error querying databases", "dsn", loggableDSN(dsn), "err", err)
 			continue
 		}
 		for _, databaseName := range databaseNames {
@@ -109,7 +109,7 @@ func (e *Exporter) scrapeDSN(ch chan<- prometheus.Metric, dsn string) error {
 
 	// Check if map versions need to be updated
 	if err := e.checkMapVersions(ch, server); err != nil {
-		logger.Warn("Proceeding with outdated query maps, as the Postgres version could not be determined", "err", err)
+		e.logger.Warn("Proceeding with outdated query maps, as the Postgres version could not be determined", "err", err)
 	}
 
 	return server.Scrape(ch, e.disableSettingsMetrics)
@@ -119,7 +119,7 @@ func (e *Exporter) scrapeDSN(ch chan<- prometheus.Metric, dsn string) error {
 // DATA_SOURCE_NAME always wins so we do not break older versions
 // reading secrets from files wins over secrets in environment variables
 // DATA_SOURCE_NAME > DATA_SOURCE_{USER|PASS}_FILE > DATA_SOURCE_{USER|PASS}
-func getDataSources() ([]string, error) {
+func GetDataSources() ([]string, error) {
 	var dsn = os.Getenv("DATA_SOURCE_NAME")
 	if len(dsn) != 0 {
 		return strings.Split(dsn, ","), nil

cmd/postgres_exporter/namespace.go → exporter/namespace.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package exporter
 
 import (
 	"database/sql"
@@ -129,7 +129,7 @@ func queryNamespaceMapping(server *Server, namespace string, mapping MetricMapNa
 						nonfatalErrors = append(nonfatalErrors, errors.New(fmt.Sprintln("Missing column: ", namespace, columnName+"_sum")))
 						continue
 					}
-					sum, ok := dbToFloat64(columnData[idx])
+					sum, ok := dbToFloat64(columnData[idx], server.logger)
 					if !ok {
 						nonfatalErrors = append(nonfatalErrors, errors.New(fmt.Sprintln("Unexpected error parsing column: ", namespace, columnName+"_sum", columnData[idx])))
 						continue
@@ -140,7 +140,7 @@ func queryNamespaceMapping(server *Server, namespace string, mapping MetricMapNa
 						nonfatalErrors = append(nonfatalErrors, errors.New(fmt.Sprintln("Missing column: ", namespace, columnName+"_count")))
 						continue
 					}
-					count, ok := dbToUint64(columnData[idx])
+					count, ok := dbToUint64(columnData[idx], server.logger)
 					if !ok {
 						nonfatalErrors = append(nonfatalErrors, errors.New(fmt.Sprintln("Unexpected error parsing column: ", namespace, columnName+"_count", columnData[idx])))
 						continue
@@ -152,7 +152,7 @@ func queryNamespaceMapping(server *Server, namespace string, mapping MetricMapNa
 						labels...,
 					)
 				} else {
-					value, ok := dbToFloat64(columnData[idx])
+					value, ok := dbToFloat64(columnData[idx], server.logger)
 					if !ok {
 						nonfatalErrors = append(nonfatalErrors, errors.New(fmt.Sprintln("Unexpected error parsing column: ", namespace, columnName, columnData[idx])))
 						continue
@@ -167,7 +167,7 @@ func queryNamespaceMapping(server *Server, namespace string, mapping MetricMapNa
 
 				// Its not an error to fail here, since the values are
 				// unexpected anyway.
-				value, ok := dbToFloat64(columnData[idx])
+				value, ok := dbToFloat64(columnData[idx], server.logger)
 				if !ok {
 					nonfatalErrors = append(nonfatalErrors, errors.New(fmt.Sprintln("Unparseable column type - discarding: ", namespace, columnName, err)))
 					continue
@@ -189,10 +189,10 @@ func queryNamespaceMappings(ch chan<- prometheus.Metric, server *Server) map[str
 	scrapeStart := time.Now()
 
 	for namespace, mapping := range server.metricMap {
-		logger.Debug("Querying namespace", "namespace", namespace)
+		server.logger.Debug("Querying namespace", "namespace", namespace)
 
 		if mapping.master && !server.master {
-			logger.Debug("Query skipped...")
+			server.logger.Debug("Query skipped...")
 			continue
 		}
 
@@ -201,7 +201,7 @@ func queryNamespaceMappings(ch chan<- prometheus.Metric, server *Server) map[str
 			serVersion, _ := semver.Parse(server.lastMapVersion.String())
 			runServerRange, _ := semver.ParseRange(server.runonserver)
 			if !runServerRange(serVersion) {
-				logger.Debug("Query skipped for this database version", "version", server.lastMapVersion.String(), "target_version", server.runonserver)
+				server.logger.Debug("Query skipped for this database version", "version", server.lastMapVersion.String(), "target_version", server.runonserver)
 				continue
 			}
 		}
@@ -232,12 +232,12 @@ func queryNamespaceMappings(ch chan<- prometheus.Metric, server *Server) map[str
 		// Serious error - a namespace disappeared
 		if err != nil {
 			namespaceErrors[namespace] = err
-			logger.Info("error finding namespace", "err", err)
+			server.logger.Info("error finding namespace", "err", err)
 		}
 		// Non-serious errors - likely version or parsing problems.
 		if len(nonFatalErrors) > 0 {
 			for _, err := range nonFatalErrors {
-				logger.Info("error querying namespace", "err", err)
+				server.logger.Info("error querying namespace", "err", err)
 			}
 		}
 

cmd/postgres_exporter/pg_setting.go → exporter/pg_setting.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package main
+package exporter
 
 import (
 	"fmt"
@@ -31,7 +31,7 @@ var (
 
 // Query the pg_settings view containing runtime variables
 func querySettings(ch chan<- prometheus.Metric, server *Server) error {
-	logger.Debug("Querying pg_setting view", "server", server)
+	server.logger.Debug("Querying pg_setting view", "server", server)
 
 	// pg_settings docs: https://www.postgresql.org/docs/current/static/view-pg-settings.html
 	//

cmd/postgres_exporter/pg_setting_test.go → exporter/pg_setting_test.go

@@ -13,7 +13,7 @@
 
 //go:build !integration
 
-package main
+package exporter
 
 import (
 	"github.com/prometheus/client_golang/prometheus"