SMPROD-20718 Fix golangci-lint workflow and reported linter errors

.github/workflows/golangci-lint.yml

@@ -1,6 +1,5 @@
 ---
 # This action is synced from https://github.com/prometheus/prometheus
-version: 1
 name: golangci-lint
 on:
   push:
@@ -26,11 +25,12 @@ jobs:
       - name: install Go
         uses: actions/setup-go@v5
         with:
-          go-version: 1.25.x
+          go-version: 1.26.x
       - name: Install snmp_exporter/generator dependencies
         run: sudo apt-get update && sudo apt-get -y install libsnmp-dev
         if: github.repository == 'prometheus/snmp_exporter'
       - name: Lint
         uses: golangci/golangci-lint-action@v8
         with:
-          version: v2.4.0
+          version: v2.12.2
+          install-mode: goinstall

.golangci.yml

@@ -1,23 +1,23 @@
 ---
+version: "2"
+
 linters:
   enable:
-  - misspell
-  - revive
-
-issues:
-  exclude-rules:
-  - path: _test.go
-    linters:
-    - errcheck
-
-linters-settings:
-  errcheck:
-    exclude-functions:
-      # Never check for logger errors.
-      - (github.com/go-kit/log.Logger).Log
-  revive:
+    - misspell
+    - revive
+  settings:
+    errcheck:
+      exclude-functions:
+        # Never check for logger errors.
+        - (github.com/go-kit/log.Logger).Log
+    revive:
+      rules:
+        # https://github.com/mgechev/revive/blob/master/RULES_DESCRIPTIONS.md#unused-parameter
+        - name: unused-parameter
+          severity: warning
+          disabled: true
+  exclusions:
     rules:
-      # https://github.com/mgechev/revive/blob/master/RULES_DESCRIPTIONS.md#unused-parameter
-      - name: unused-parameter
-        severity: warning
-        disabled: true
+      - path: _test.go
+        linters:
+          - errcheck

cmd/postgres_exporter/namespace.go

@@ -45,12 +45,12 @@ func queryNamespaceMapping(server *Server, namespace string, mapping MetricMapNa
 	if !found {
 		// I've no idea how to avoid this properly at the moment, but this is
 		// an admin tool so you're not injecting SQL right?
-		rows, err = server.db.Query(fmt.Sprintf("SELECT * FROM %s;", namespace)) // nolint: gas
+		rows, err = server.db.Query(fmt.Sprintf("SELECT * FROM %s;", namespace)) // nolint: gosec
 	} else {
 		rows, err = server.db.Query(query)
 	}
 	if err != nil {
-		return []prometheus.Metric{}, []error{}, fmt.Errorf("Error running query on database %q: %s %v", server, namespace, err)
+		return []prometheus.Metric{}, []error{}, fmt.Errorf("error running query on database %q: %s %v", server, namespace, err)
 	}
 	defer rows.Close() // nolint: errcheck
 

cmd/postgres_exporter/pg_setting.go

@@ -42,15 +42,15 @@ func querySettings(ch chan<- prometheus.Metric, server *Server) error {
 
 	rows, err := server.db.Query(query)
 	if err != nil {
-		return fmt.Errorf("Error running query on database %q: %s %v", server, namespace, err)
+		return fmt.Errorf("error running query on database %q: %s %v", server, namespace, err)
 	}
 	defer rows.Close() // nolint: errcheck
 
 	for rows.Next() {
 		s := &pgSetting{}
 		err = rows.Scan(&s.name, &s.setting, &s.unit, &s.shortDesc, &s.vartype)
 		if err != nil {
-			return fmt.Errorf("Error retrieving rows on %q: %s %v", server, namespace, err)
+			return fmt.Errorf("error retrieving rows on %q: %s %v", server, namespace, err)
 		}
 
 		ch <- s.metric(server.labels)
@@ -68,7 +68,7 @@ type pgSetting struct {
 func (s *pgSetting) metric(labels prometheus.Labels) prometheus.Metric {
 	var (
 		err       error
-		name      = strings.Replace(s.name, ".", "_", -1)
+		name      = strings.ReplaceAll(s.name, ".", "_")
 		unit      = s.unit // nolint: ineffassign
 		shortDesc = fmt.Sprintf("Server Parameter: %s", s.name)
 		subsystem = "settings"
@@ -120,7 +120,7 @@ func (s *pgSetting) normaliseUnit() (val float64, unit string, err error) {
 
 	val, err = strconv.ParseFloat(s.setting, 64)
 	if err != nil {
-		return val, unit, fmt.Errorf("Error converting setting %q value %q to float: %s", s.name, s.setting, err)
+		return val, unit, fmt.Errorf("error converting setting %q value %q to float: %s", s.name, s.setting, err)
 	}
 
 	// Units defined in: https://www.postgresql.org/docs/current/static/config-setting.html
@@ -132,7 +132,7 @@ func (s *pgSetting) normaliseUnit() (val float64, unit string, err error) {
 	case "B", "kB", "MB", "GB", "TB", "1kB", "2kB", "4kB", "8kB", "16kB", "32kB", "64kB", "16MB", "32MB", "64MB":
 		unit = "bytes"
 	default:
-		err = fmt.Errorf("Unknown unit for runtime variable: %q", s.unit)
+		err = fmt.Errorf("unknown unit for runtime variable: %q", s.unit)
 		return
 	}
 

cmd/postgres_exporter/postgres_exporter.go

@@ -587,11 +587,11 @@ func checkPostgresVersion(db *sql.DB, server string) (semver.Version, string, er
 	var versionString string
 	err := versionRow.Scan(&versionString)
 	if err != nil {
-		return semver.Version{}, "", fmt.Errorf("Error scanning version string on %q: %v", server, err)
+		return semver.Version{}, "", fmt.Errorf("error scanning version string on %q: %v", server, err)
 	}
 	semanticVersion, err := parseVersion(versionString)
 	if err != nil {
-		return semver.Version{}, "", fmt.Errorf("Error parsing version string on %q: %v", server, err)
+		return semver.Version{}, "", fmt.Errorf("error parsing version string on %q: %v", server, err)
 	}
 
 	return semanticVersion, versionString, nil
@@ -601,7 +601,7 @@ func checkPostgresVersion(db *sql.DB, server string) (semver.Version, string, er
 func (e *Exporter) checkMapVersions(ch chan<- prometheus.Metric, server *Server) error {
 	semanticVersion, versionString, err := checkPostgresVersion(server.db, server.String())
 	if err != nil {
-		return fmt.Errorf("Error fetching version string on %q: %v", server, err)
+		return fmt.Errorf("error fetching version string on %q: %v", server, err)
 	}
 
 	if !e.disableDefaultMetrics && semanticVersion.LT(lowestSupportedVersion) {

cmd/postgres_exporter/probe.go

@@ -91,7 +91,7 @@ func handleProbe(logger log.Logger, excludeDatabases []string) http.HandlerFunc
 		}
 
 		// Cleanup underlying connections to prevent connection leaks
-		defer pc.Close()
+		defer func() { _ = pc.Close() }()
 
 		// TODO(@sysadmind): Remove the registry.MustRegister() call below and instead handle the collection here. That will allow
 		// for the passing of context, handling of timeouts, and more control over the collection.

cmd/postgres_exporter/queries.go

@@ -266,7 +266,7 @@ func addQueries(content []byte, pgVersion semver.Version, server *Server) error
 func queryDatabases(server *Server) ([]string, error) {
 	rows, err := server.db.Query("SELECT datname FROM pg_database WHERE datallowconn = true AND datistemplate = false AND datname != current_database()")
 	if err != nil {
-		return nil, fmt.Errorf("Error retrieving databases: %v", err)
+		return nil, fmt.Errorf("error retrieving databases: %v", err)
 	}
 	defer rows.Close() // nolint: errcheck
 

collector/collector.go

@@ -176,7 +176,7 @@ func (p PostgresCollector) Collect(ch chan<- prometheus.Metric) {
 		level.Error(p.logger).Log("msg", "Error opening connection to database", "err", err)
 		return
 	}
-	defer inst.Close()
+	defer func() { _ = inst.Close() }()
 
 	wg := sync.WaitGroup{}
 	wg.Add(len(p.Collectors))

collector/collector_test.go

@@ -48,15 +48,15 @@ func readMetric(m prometheus.Metric) MetricResult {
 
 func sanitizeQuery(q string) string {
 	q = strings.Join(strings.Fields(q), " ")
-	q = strings.Replace(q, "(", "\\(", -1)
-	q = strings.Replace(q, "?", "\\?", -1)
-	q = strings.Replace(q, ")", "\\)", -1)
-	q = strings.Replace(q, "[", "\\[", -1)
-	q = strings.Replace(q, "]", "\\]", -1)
-	q = strings.Replace(q, "{", "\\{", -1)
-	q = strings.Replace(q, "}", "\\}", -1)
-	q = strings.Replace(q, "*", "\\*", -1)
-	q = strings.Replace(q, "^", "\\^", -1)
-	q = strings.Replace(q, "$", "\\$", -1)
+	q = strings.ReplaceAll(q, "(", "\\(")
+	q = strings.ReplaceAll(q, "?", "\\?")
+	q = strings.ReplaceAll(q, ")", "\\)")
+	q = strings.ReplaceAll(q, "[", "\\[")
+	q = strings.ReplaceAll(q, "]", "\\]")
+	q = strings.ReplaceAll(q, "{", "\\{")
+	q = strings.ReplaceAll(q, "}", "\\}")
+	q = strings.ReplaceAll(q, "*", "\\*")
+	q = strings.ReplaceAll(q, "^", "\\^")
+	q = strings.ReplaceAll(q, "$", "\\$")
 	return q
 }

collector/instance.go

@@ -38,7 +38,7 @@ func newInstance(dsn string) (*instance, error) {
 	if err != nil {
 		return nil, err
 	}
-	db.Close()
+	_ = db.Close()
 
 	return i, nil
 }

collector/pg_database.go

@@ -75,7 +75,7 @@ func (c PGDatabaseCollector) Update(ctx context.Context, instance *instance, ch
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	var databases []string
 

collector/pg_database_wraparound.go

@@ -70,7 +70,7 @@ func (c *PGDatabaseWraparoundCollector) Update(ctx context.Context, instance *in
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
 		var datname sql.NullString

collector/pg_locks.go

@@ -97,7 +97,7 @@ func (c PGLocksCollector) Update(ctx context.Context, instance *instance, ch cha
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	var datname, mode sql.NullString
 	var count sql.NullInt64

collector/pg_long_running_transactions.go

@@ -66,7 +66,7 @@ func (PGLongRunningTransactionsCollector) Update(ctx context.Context, instance *
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
 		var transactions, ageInSeconds float64

collector/pg_replication_slot.go

@@ -84,7 +84,7 @@ func (PGReplicationSlotCollector) Update(ctx context.Context, instance *instance
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
 		var slotName sql.NullString

collector/pg_stat_activity_autovacuum.go

@@ -61,7 +61,7 @@ func (PGStatActivityAutovacuumCollector) Update(ctx context.Context, instance *i
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
 		var relname string

collector/pg_stat_database.go

@@ -250,7 +250,7 @@ func (c *PGStatDatabaseCollector) Update(ctx context.Context, instance *instance
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
 		var datid, datname sql.NullString

collector/pg_stat_statements.go

@@ -126,7 +126,7 @@ func (PGStatStatementsCollector) Update(ctx context.Context, instance *instance,
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 	for rows.Next() {
 		var user, datname, queryid sql.NullString
 		var callsTotal, rowsTotal sql.NullInt64

collector/pg_stat_user_tables.go

@@ -193,7 +193,7 @@ func (c *PGStatUserTablesCollector) Update(ctx context.Context, instance *instan
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
 		var datname, schemaname, relname sql.NullString

collector/pg_stat_walreceiver.go

@@ -135,13 +135,13 @@ func (c *PGStatWalReceiverCollector) Update(ctx context.Context, instance *insta
 		query = fmt.Sprintf(pgStatWalReceiverQueryTemplate, "")
 	}
 
-	hasFlushedLSNRows.Close()
+	_ = hasFlushedLSNRows.Close()
 
 	rows, err := db.QueryContext(ctx, query)
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 	for rows.Next() {
 		var upstreamHost, slotName, status sql.NullString
 		var receiveStartLsn, receiveStartTli, flushedLsn, receivedTli, latestEndLsn, upstreamNode sql.NullInt64

collector/pg_statio_user_indexes.go

@@ -67,7 +67,7 @@ func (c *PGStatioUserIndexesCollector) Update(ctx context.Context, instance *ins
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 	for rows.Next() {
 		var schemaname, relname, indexrelname sql.NullString
 		var idxBlksRead, idxBlksHit sql.NullFloat64

collector/pg_statio_user_tables.go

@@ -108,7 +108,7 @@ func (PGStatIOUserTablesCollector) Update(ctx context.Context, instance *instanc
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
 		var datname, schemaname, relname sql.NullString

collector/pg_xlog_location.go

@@ -69,7 +69,7 @@ func (c PGXlogLocationCollector) Update(ctx context.Context, instance *instance,
 	if err != nil {
 		return err
 	}
-	defer rows.Close()
+	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
 		var bytes float64

collector/probe.go

@@ -81,7 +81,7 @@ func (pc *ProbeCollector) Collect(ch chan<- prometheus.Metric) {
 		level.Error(pc.logger).Log("msg", "Error opening connection to database", "err", err)
 		return
 	}
-	defer pc.instance.Close()
+	defer func() { _ = pc.instance.Close() }()
 
 	wg := sync.WaitGroup{}
 	wg.Add(len(pc.collectors))

config/config.go

@@ -79,14 +79,14 @@ func (ch *Handler) ReloadConfig(f string, logger log.Logger) error {
 
 	yamlReader, err := os.Open(f)
 	if err != nil {
-		return fmt.Errorf("Error opening config file %q: %s", f, err)
+		return fmt.Errorf("error opening config file %q: %s", f, err)
 	}
-	defer yamlReader.Close()
+	defer func() { _ = yamlReader.Close() }()
 	decoder := yaml.NewDecoder(yamlReader)
 	decoder.KnownFields(true)
 
 	if err = decoder.Decode(config); err != nil {
-		return fmt.Errorf("Error parsing config file %q: %s", f, err)
+		return fmt.Errorf("error parsing config file %q: %s", f, err)
 	}
 
 	ch.Lock()