Update loggers to use slog instead of go-kit/log

Port of previous wrok from @dehaansa
From dee62ca

Author: cristiangreco

cmd/postgres_exporter/datasource.go

@@ -39,19 +39,19 @@ func (e *Exporter) discoverDatabaseDSNs() []string {
 			var err error
 			dsnURI, err = url.Parse(dsn)
 			if err != nil {
-				level.Error(e.logger).Log("msg", "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 {
-			level.Error(e.logger).Log("msg", "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 {
-			level.Error(e.logger).Log("msg", "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 {
-			level.Error(e.logger).Log("msg", "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 {
-		level.Warn(e.logger).Log("msg", "Proceeding with outdated query maps, as the Postgres version could not be determined", "err", err)
+		e.logger.Warn("Proceeding with outdated query maps, as the Postgres version could not be determined", "err", err)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)

cmd/postgres_exporter/main.go

@@ -50,7 +50,7 @@ var (
 	includeDatabases       = kingpin.Flag("include-databases", "A list of databases to include when autoDiscoverDatabases is enabled (DEPRECATED)").Default("").Envar("PG_EXPORTER_INCLUDE_DATABASES").String()
 
 	// rootFallbackLogger is used when we cannot use the regular logger in this fork. Under normal operations, there shouldn't be anything logged using this.
-	rootFallbackLogger = log.NewLogfmtLogger(os.Stderr)
+	rootFallbackLogger = promslog.New(&promslog.Config{})
 )
 
 // Metric name parts.
@@ -82,28 +82,28 @@ func main() {
 
 	if err := c.ReloadConfig(*configFile, rootFallbackLogger); err != nil {
 		// This is not fatal, but it means that auth must be provided for every dsn.
-		level.Warn(rootFallbackLogger).Log("msg", "Error loading config", "err", err)
+		rootFallbackLogger.Warn("Error loading config", "err", err)
 	}
 
 	dsns, err := getDataSources()
 	if err != nil {
-		level.Error(rootFallbackLogger).Log("msg", "Failed reading data sources", "err", err.Error())
+		rootFallbackLogger.Error("Failed reading data sources", "err", err.Error())
 		os.Exit(1)
 	}
 
 	excludedDatabases := strings.Split(*excludeDatabases, ",")
-	rootFallbackLogger.Log("msg", "Excluded databases", "databases", fmt.Sprintf("%v", excludedDatabases))
+	rootFallbackLogger.Info("Excluded databases", "databases", fmt.Sprintf("%v", excludedDatabases))
 
 	if *queriesPath != "" {
-		level.Warn(rootFallbackLogger).Log("msg", "The extended queries.yaml config is DEPRECATED", "file", *queriesPath)
+		rootFallbackLogger.Warn("The extended queries.yaml config is DEPRECATED", "file", *queriesPath)
 	}
 
 	if *autoDiscoverDatabases || *excludeDatabases != "" || *includeDatabases != "" {
-		level.Warn(rootFallbackLogger).Log("msg", "Scraping additional databases via auto discovery is DEPRECATED")
+		rootFallbackLogger.Warn("Scraping additional databases via auto discovery is DEPRECATED")
 	}
 
 	if *constantLabelsList != "" {
-		level.Warn(rootFallbackLogger).Log("msg", "Constant labels on all metrics is DEPRECATED")
+		rootFallbackLogger.Warn("Constant labels on all metrics is DEPRECATED")
 	}
 
 	opts := []ExporterOpt{
@@ -138,7 +138,7 @@ func main() {
 		[]string{},
 	)
 	if err != nil {
-		level.Warn(rootFallbackLogger).Log("msg", "Failed to create PostgresCollector", "err", err.Error())
+		rootFallbackLogger.Warn("Failed to create PostgresCollector", "err", err.Error())
 	} else {
 		prometheus.MustRegister(pe)
 	}
@@ -159,7 +159,7 @@ func main() {
 		}
 		landingPage, err := web.NewLandingPage(landingConfig)
 		if err != nil {
-			level.Error(rootFallbackLogger).Log("err", err)
+			rootFallbackLogger.Error("Error initializing landing page", "err", err)
 			os.Exit(1)
 		}
 		http.Handle("/", landingPage)
@@ -169,7 +169,7 @@ func main() {
 
 	srv := &http.Server{}
 	if err := web.ListenAndServe(srv, webConfig, rootFallbackLogger); err != nil {
-		level.Error(rootFallbackLogger).Log("msg", "Error running HTTP server", "err", err)
+		rootFallbackLogger.Error("Error running HTTP server", "err", err)
 		os.Exit(1)
 	}
 }

cmd/postgres_exporter/namespace.go

@@ -189,10 +189,10 @@ func queryNamespaceMappings(ch chan<- prometheus.Metric, server *Server) map[str
 	scrapeStart := time.Now()
 
 	for namespace, mapping := range server.metricMap {
-		level.Debug(server.logger).Log("msg", "Querying namespace", "namespace", namespace)
+		server.logger.Debug("Querying namespace", "namespace", namespace)
 
 		if mapping.master && !server.master {
-			level.Debug(server.logger).Log("msg", "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) {
-				level.Debug(server.logger).Log("msg", "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
-			level.Info(server.logger).Log("err", err)
+			server.logger.Info("error encountered querying namespace metrics", "err", err)
 		}
 		// Non-serious errors - likely version or parsing problems.
 		if len(nonFatalErrors) > 0 {
 			for _, err := range nonFatalErrors {
-				level.Info(server.logger).Log("err", err)
+				server.logger.Info("nonfatal error encountered querying namespace metrics", "err", err)
 			}
 		}
 

cmd/postgres_exporter/pg_setting.go

@@ -31,7 +31,7 @@ var (
 
 // Query the pg_settings view containing runtime variables
 func querySettings(ch chan<- prometheus.Metric, server *Server) error {
-	level.Debug(server.logger).Log("msg", "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/postgres_exporter.go

@@ -18,16 +18,16 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"log/slog"
 	"math"
 	"os"
 	"regexp"
 	"strings"
 	"time"
 
 	"github.com/blang/semver/v4"
-	"github.com/go-kit/log"
-	"github.com/go-kit/log/level"
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/promslog"
 )
 
 // ColumnUsage should be one of several enum values which describe how a
@@ -265,7 +265,7 @@ var builtinMetricMaps = map[string]intermediateMetricMap{
 }
 
 // Turn the MetricMap column mapping into a prometheus descriptor mapping.
-func makeDescMap(pgVersion semver.Version, serverLabels prometheus.Labels, metricMaps map[string]intermediateMetricMap, logger log.Logger, metricPrefix string) map[string]MetricMapNamespace {
+func makeDescMap(pgVersion semver.Version, serverLabels prometheus.Labels, metricMaps map[string]intermediateMetricMap, logger *slog.Logger, metricPrefix string) map[string]MetricMapNamespace {
 	var metricMap = make(map[string]MetricMapNamespace)
 
 	for namespace, intermediateMappings := range metricMaps {
@@ -427,7 +427,7 @@ type Exporter struct {
 	// servers are used to allow re-using the DB connection between scrapes.
 	// servers contains metrics map and query overrides.
 	servers      *Servers
-	logger       log.Logger
+	logger       *slog.Logger
 	metricPrefix string
 }
 
@@ -486,7 +486,7 @@ func WithConstantLabels(s string) ExporterOpt {
 }
 
 // WithLogger configures logger.
-func WithLogger(logger log.Logger) ExporterOpt {
+func WithLogger(logger *slog.Logger) ExporterOpt {
 	return func(e *Exporter) {
 		e.logger = logger
 	}
@@ -511,7 +511,7 @@ func parseConstLabels(s string) prometheus.Labels {
 	for _, p := range parts {
 		keyValue := strings.Split(strings.TrimSpace(p), "=")
 		if len(keyValue) != 2 {
-			level.Error(rootFallbackLogger).Log(`Wrong constant labels format, should be "key=value"`, "input", p)
+			rootFallbackLogger.Error(`Wrong constant labels format, should be "key=value"`, "input", p)
 			continue
 		}
 		key := strings.TrimSpace(keyValue[0])
@@ -530,7 +530,7 @@ func NewExporter(dsn []string, opts ...ExporterOpt) *Exporter {
 	e := &Exporter{
 		dsn:               dsn,
 		builtinMetricMaps: builtinMetricMaps,
-		logger:            log.NewNopLogger(), // Can override with WithLogger option
+		logger:            promslog.NewNopLogger(), // Can override with WithLogger option
 	}
 
 	for _, opt := range opts {
@@ -602,8 +602,8 @@ func newDesc(subsystem, name, help string, labels prometheus.Labels) *prometheus
 	)
 }
 
-func checkPostgresVersion(db *sql.DB, server string, logger log.Logger) (semver.Version, string, error) {
-	level.Debug(logger).Log("msg", "Querying PostgreSQL version", "server", server)
+func checkPostgresVersion(db *sql.DB, server string, logger *slog.Logger) (semver.Version, string, error) {
+	logger.Debug("Querying PostgreSQL version", "server", server)
 	versionRow := db.QueryRow("SELECT version();")
 	var versionString string
 	err := versionRow.Scan(&versionString)
@@ -626,12 +626,12 @@ func (e *Exporter) checkMapVersions(ch chan<- prometheus.Metric, server *Server)
 	}
 
 	if !e.disableDefaultMetrics && semanticVersion.LT(lowestSupportedVersion) {
-		level.Warn(server.logger).Log("msg", "PostgreSQL version is lower than our lowest supported version", "server", server, "version", semanticVersion, "lowest_supported_version", lowestSupportedVersion)
+		server.logger.Warn("PostgreSQL version is lower than our lowest supported version", "server", server, "version", semanticVersion, "lowest_supported_version", lowestSupportedVersion)
 	}
 
 	// Check if semantic version changed and recalculate maps if needed.
 	if semanticVersion.NE(server.lastMapVersion) || server.metricMap == nil {
-		level.Info(server.logger).Log("msg", "Semantic version changed", "server", server, "from", server.lastMapVersion, "to", semanticVersion)
+		server.logger.Info("Semantic version changed", "server", server, "from", server.lastMapVersion, "to", semanticVersion)
 		server.mappingMtx.Lock()
 
 		// Get Default Metrics only for master database
@@ -652,13 +652,13 @@ func (e *Exporter) checkMapVersions(ch chan<- prometheus.Metric, server *Server)
 			// Calculate the hashsum of the useQueries
 			userQueriesData, err := os.ReadFile(e.userQueriesPath)
 			if err != nil {
-				level.Error(server.logger).Log("msg", "Failed to reload user queries", "path", e.userQueriesPath, "err", err)
+				server.logger.Error("Failed to reload user queries", "path", e.userQueriesPath, "err", err)
 				e.userQueriesError.WithLabelValues(e.userQueriesPath, "").Set(1)
 			} else {
 				hashsumStr := fmt.Sprintf("%x", sha256.Sum256(userQueriesData))
 
 				if err := addQueries(userQueriesData, semanticVersion, server, e.metricPrefix); err != nil {
-					level.Error(server.logger).Log("msg", "Failed to reload user queries", "path", e.userQueriesPath, "err", err)
+					server.logger.Error("Failed to reload user queries", "path", e.userQueriesPath, "err", err)
 					e.userQueriesError.WithLabelValues(e.userQueriesPath, hashsumStr).Set(1)
 				} else {
 					// Mark user queries as successfully loaded
@@ -700,7 +700,7 @@ func (e *Exporter) scrape(ch chan<- prometheus.Metric) {
 		if err := e.scrapeDSN(ch, dsn); err != nil {
 			errorsCount++
 
-			level.Error(e.logger).Log("err", err)
+			e.logger.Error("error encountered scraping DSN", "err", err)
 
 			if _, ok := err.(*ErrorConnectToServer); ok {
 				connectionErrorsCount++

cmd/postgres_exporter/postgres_exporter_test.go

@@ -24,8 +24,8 @@ import (
 	"time"
 
 	"github.com/blang/semver/v4"
-	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/promslog"
 	. "gopkg.in/check.v1"
 )
 
@@ -55,7 +55,7 @@ func (s *FunctionalSuite) TestSemanticVersionColumnDiscard(c *C) {
 
 	{
 		// No metrics should be eliminated
-		resultMap := makeDescMap(semver.MustParse("0.0.1"), prometheus.Labels{}, testMetricMap, log.NewLogfmtLogger(os.Stderr), "pg")
+		resultMap := makeDescMap(semver.MustParse("0.0.1"), prometheus.Labels{}, testMetricMap, promslog.New(&promslog.Config{}), "pg")
 		c.Check(
 			resultMap["test_namespace"].columnMappings["metric_which_stays"].discard,
 			Equals,
@@ -76,7 +76,7 @@ func (s *FunctionalSuite) TestSemanticVersionColumnDiscard(c *C) {
 		testMetricMap["test_namespace"].columnMappings["metric_which_discards"] = discardableMetric
 
 		// Discard metric should be discarded
-		resultMap := makeDescMap(semver.MustParse("0.0.1"), prometheus.Labels{}, testMetricMap, log.NewLogfmtLogger(os.Stderr), "pg")
+		resultMap := makeDescMap(semver.MustParse("0.0.1"), prometheus.Labels{}, testMetricMap, promslog.New(&promslog.Config{}), "pg")
 		c.Check(
 			resultMap["test_namespace"].columnMappings["metric_which_stays"].discard,
 			Equals,
@@ -97,7 +97,7 @@ func (s *FunctionalSuite) TestSemanticVersionColumnDiscard(c *C) {
 		testMetricMap["test_namespace"].columnMappings["metric_which_discards"] = discardableMetric
 
 		// Discard metric should be discarded
-		resultMap := makeDescMap(semver.MustParse("0.0.2"), prometheus.Labels{}, testMetricMap, log.NewLogfmtLogger(os.Stderr), "pg")
+		resultMap := makeDescMap(semver.MustParse("0.0.2"), prometheus.Labels{}, testMetricMap, promslog.New(&promslog.Config{}), "pg")
 		c.Check(
 			resultMap["test_namespace"].columnMappings["metric_which_stays"].discard,
 			Equals,
@@ -411,7 +411,7 @@ func (s *FunctionalSuite) TestBooleanConversionToValueAndString(c *C) {
 func (s *FunctionalSuite) TestParseUserQueries(c *C) {
 	userQueriesData, err := os.ReadFile("./tests/user_queries_ok.yaml")
 	if err == nil {
-		metricMaps, newQueryOverrides, err := parseUserQueries(userQueriesData, log.NewLogfmtLogger(os.Stderr))
+		metricMaps, newQueryOverrides, err := parseUserQueries(userQueriesData, promslog.New(&promslog.Config{}))
 		c.Assert(err, Equals, nil)
 		c.Assert(metricMaps, NotNil)
 		c.Assert(newQueryOverrides, NotNil)

cmd/postgres_exporter/queries.go

@@ -16,7 +16,7 @@ package postgres_exporter
 import (
 	"errors"
 	"fmt"
-	"github.com/go-kit/log"
+	"log/slog"
 
 	"github.com/blang/semver/v4"
 	"gopkg.in/yaml.v2"
@@ -168,7 +168,7 @@ var queryOverrides = map[string][]OverrideQuery{
 
 // Convert the query override file to the version-specific query override file
 // for the exporter.
-func makeQueryOverrideMap(pgVersion semver.Version, queryOverrides map[string][]OverrideQuery, logger log.Logger) map[string]string {
+func makeQueryOverrideMap(pgVersion semver.Version, queryOverrides map[string][]OverrideQuery, logger *slog.Logger) map[string]string {
 	resultMap := make(map[string]string)
 	for name, overrideDef := range queryOverrides {
 		// Find a matching semver. We make it an error to have overlapping
@@ -190,7 +190,7 @@ func makeQueryOverrideMap(pgVersion semver.Version, queryOverrides map[string][]
 	return resultMap
 }
 
-func parseUserQueries(content []byte, logger log.Logger) (map[string]intermediateMetricMap, map[string]string, error) {
+func parseUserQueries(content []byte, logger *slog.Logger) (map[string]intermediateMetricMap, map[string]string, error) {
 	var userQueries UserQueries
 
 	err := yaml.Unmarshal(content, &userQueries)
@@ -255,9 +255,9 @@ func addQueries(content []byte, pgVersion semver.Version, server *Server, metric
 	for k, v := range partialExporterMap {
 		_, found := server.metricMap[k]
 		if found {
-			level.Debug(server.logger).Log("msg", "Overriding metric from user YAML file", "metric", k)
+			server.logger.Debug("Overriding metric from user YAML file", "metric", k)
 		} else {
-			level.Debug(server.logger).Log("msg", "Adding new metric from user YAML file", "metric", k)
+			server.logger.Debug("Adding new metric from user YAML file", "metric", k)
 		}
 		server.metricMap[k] = v
 	}
@@ -266,9 +266,9 @@ func addQueries(content []byte, pgVersion semver.Version, server *Server, metric
 	for k, v := range newQueryOverrides {
 		_, found := server.queryOverrides[k]
 		if found {
-			level.Debug(server.logger).Log("msg", "Overriding query override from user YAML file", "query_override", k)
+			server.logger.Debug("Overriding query override from user YAML file", "query_override", k)
 		} else {
-			level.Debug(server.logger).Log("msg", "Adding new query override from user YAML file", "query_override", k)
+			server.logger.Debug("Adding new query override from user YAML file", "query_override", k)
 		}
 		server.queryOverrides[k] = v
 	}