Add revive as linter (#243)

Add revive as linter

https://github.com/mgechev/revive

Fixed most of the issues and relaxed some of the rules regarding method
length and complexity to avoid need to write some of the scrapers on
this iteration..

Also update to go 1.24.5 and add docker compose with prometheus and
postgres 14.

.github/workflows/build.yaml

@@ -35,7 +35,7 @@ jobs:
       - name: set up go
         uses: actions/setup-go@v5
         with:
-          go-version: 1.22.1
+          go-version: 1.23.5
         id: go
       - name: go mod tidy
         run: go mod tidy
@@ -55,7 +55,7 @@ jobs:
       - name: set up go
         uses: actions/setup-go@v5
         with:
-          go-version: 1.22.1
+          go-version: 1.23.5
         id: go
       - run: go version
       - name: Promu

.golangci.yaml

@@ -1,7 +1,4 @@
 ---
-run:
-  deadline: 5m
-
 output:
   sort-results: true
 
@@ -10,7 +7,7 @@ linters:
     # - depguard
     - gofumpt
     - goimports
-    # - revive
+    - revive
     - bodyclose
     # - gochecknoglobals
     - errname
@@ -25,5 +22,18 @@ linters:
     - sqlclosecheck
 
 linters-settings:
+  revive:
+    enable-all-rules: true
+    ignore-generated-header: true
+    rules:
+      - name: line-length-limit
+        arguments: [160]
+      - name: function-length
+        arguments: [50, 150] # Maximum number of lines allowed in a function
+      - name: cognitive-complexity
+        arguments: [12]
+      - name: cyclomatic
+        arguments: [12]
   errcheck:
-    exclude: .errcheck_excludes.txt
+    exclude-functions:
+      - (github.com/go-kit/log.Logger).Log

.promu.yml

@@ -1,6 +1,6 @@
 ---
 go:
-  version: 1.22.1
+  version: 1.23.5
 repository:
   path: github.com/rnaveiras/postgres_exporter
 build:

Dockerfile

@@ -1,8 +1,7 @@
-# syntax=docker/dockerfile:1
-FROM golang:1.22.1-alpine3.19 as builder
+FROM golang:1.23.5-alpine3.21 AS builder
 
 ENV PROMU_SHA256=f92fd94dbd5941c7f2925860c3d6a1f24b7630cb2b192df43835c8dda9e76b5d \
-    PROMU_VERSION=0.15.0
+  PROMU_VERSION=0.15.0
 
 SHELL ["/bin/ash", "-euox", "pipefail", "-c"]
 
@@ -23,7 +22,7 @@ RUN set -x \
   && find ./output
 
 FROM alpine:3.19
-LABEL maintainer="Raul Naveiras <rnaveiras@gmail.com>"
+LABEL org.opencontainers.image.authors="Raul Naveiras <rnaveiras@gmail.com>"
 
 COPY --from=builder /go/src/app/output/postgres_exporter /bin/postgres_exporter
 

collector/disk_usage.go

@@ -45,11 +45,11 @@ func NewDiskUsageScraper() Scraper {
 	}
 }
 
-func (c *diskUsageScraper) Name() string {
+func (*diskUsageScraper) Name() string {
 	return "DiskUsageScraper"
 }
 
-func (c *diskUsageScraper) Scrape(ctx context.Context, conn *pgx.Conn, version Version, ch chan<- prometheus.Metric) error {
+func (c *diskUsageScraper) Scrape(ctx context.Context, conn *pgx.Conn, _ Version, ch chan<- prometheus.Metric) error {
 	var datname, schemaname, tablename, indexname string
 	var sizeBytes float64
 	var rows pgx.Rows

collector/exporter.go

@@ -13,6 +13,19 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+const (
+	versionBitSize   = 64
+	infoQuery        = `SHOW server_version /*postgres_exporter*/`
+	listDatnameQuery = `
+SELECT datname FROM pg_database
+WHERE datallowconn = true AND datistemplate = false
+AND datname != 'cloudsqladmin' /*postgres_exporter*/`
+	successValue    = 1.0
+	failureValue    = 0.0
+	infoMetricValue = 1.0
+	levelError      = "error" // Used for error logging
+)
+
 var (
 	upDesc = prometheus.NewDesc(
 		"postgres_up",
@@ -40,14 +53,6 @@ var (
 	)
 )
 
-const (
-	infoQuery        = `SHOW server_version /*postgres_exporter*/`
-	listDatnameQuery = `
-SELECT datname FROM pg_database
-WHERE datallowconn = true AND datistemplate = false
-AND datname != 'cloudsqladmin' /*postgres_exporter*/`
-)
-
 // Scraper is the interface each scraper has to implement.
 type Scraper interface {
 	Name() string
@@ -70,7 +75,7 @@ type Version struct {
 
 func NewVersion(v string) Version {
 	values := strings.Split(v, " ")
-	version, _ := strconv.ParseFloat(values[0], 64)
+	version, _ := strconv.ParseFloat(values[0], versionBitSize)
 	return Version{
 		version: version,
 	}
@@ -114,7 +119,7 @@ func NewExporter(ctx context.Context, logger kitlog.Logger, connConfig *pgx.Conn
 }
 
 // Describe implements the prometheus.Collector interface.
-func (e Exporter) Describe(ch chan<- *prometheus.Desc) {
+func (Exporter) Describe(ch chan<- *prometheus.Desc) {
 	ch <- scrapeDurationDesc
 	ch <- scrapeSuccessDesc
 }
@@ -123,31 +128,31 @@ func (e Exporter) Describe(ch chan<- *prometheus.Desc) {
 func (e Exporter) Collect(ch chan<- prometheus.Metric) {
 	conn, err := pgx.ConnectConfig(e.ctx, e.connConfig)
 	if err != nil {
-		ch <- prometheus.MustNewConstMetric(upDesc, prometheus.GaugeValue, 0)
-		level.Error(e.logger).Log("error", err)
+		ch <- prometheus.MustNewConstMetric(upDesc, prometheus.GaugeValue, failureValue)
+		level.Error(e.logger).Log(levelError, err)
 		return // cannot continue without a valid connection
 	}
 
 	defer conn.Close(e.ctx)
 	// postgres_up
-	ch <- prometheus.MustNewConstMetric(upDesc, prometheus.GaugeValue, 1)
+	ch <- prometheus.MustNewConstMetric(upDesc, prometheus.GaugeValue, successValue)
 
 	var version string
 	if err := conn.QueryRow(e.ctx, infoQuery).Scan(&version); err != nil {
-		level.Error(e.logger).Log("error", err)
+		level.Error(e.logger).Log(levelError, err)
 		return // cannot continue without a version
 	}
 
 	v := NewVersion(version)
 	// postgres_info
-	ch <- prometheus.MustNewConstMetric(infoDesc, prometheus.GaugeValue, 1, v.String())
+	ch <- prometheus.MustNewConstMetric(infoDesc, prometheus.GaugeValue, infoMetricValue, v.String())
 
 	// discovery databases
 	var dbnames []string
 
 	rows, err := conn.Query(e.ctx, listDatnameQuery)
 	if err != nil {
-		level.Error(e.logger).Log("error", err)
+		level.Error(e.logger).Log(levelError, err)
 		return
 	}
 	defer rows.Close()
@@ -156,7 +161,7 @@ func (e Exporter) Collect(ch chan<- prometheus.Metric) {
 		var dbname string
 		err := rows.Scan(&dbname)
 		if err != nil {
-			level.Error(e.logger).Log("error", err)
+			level.Error(e.logger).Log(levelError, err)
 			return
 		}
 		dbnames = append(dbnames, dbname)
@@ -175,7 +180,7 @@ func (e Exporter) Collect(ch chan<- prometheus.Metric) {
 		// establish a new connection
 		conn, err := pgx.ConnectConfig(e.ctx, e.connConfig)
 		if err != nil {
-			level.Error(e.logger).Log("error", err)
+			level.Error(e.logger).Log(levelError, err)
 			return // cannot continue without a valid connection
 		}
 
@@ -197,11 +202,11 @@ func (e Exporter) scrape(scraper Scraper, conn *pgx.Conn, version Version, ch ch
 
 	logger := kitlog.With(e.logger, "scraper", scraper.Name(), "duration", duration.Seconds())
 	if err != nil {
-		logger.Log("error", err)
-		success = 0
+		logger.Log(levelError, err)
+		success = successValue
 	} else {
 		level.Debug(logger).Log("event", "scraper.success")
-		success = 1
+		success = failureValue
 	}
 
 	datname := e.connConfig.Config.Database

collector/info.go

@@ -52,11 +52,11 @@ func NewInfoScraper() Scraper {
 	}
 }
 
-func (c *infoScraper) Name() string {
+func (*infoScraper) Name() string {
 	return "InfoScraper"
 }
 
-func (c *infoScraper) Scrape(ctx context.Context, conn *pgx.Conn, version Version, ch chan<- prometheus.Metric) error {
+func (c *infoScraper) Scrape(ctx context.Context, conn *pgx.Conn, _ Version, ch chan<- prometheus.Metric) error {
 	var recovery, backup int64
 	var startTime, configLoadTime time.Time
 

collector/locks.go

@@ -37,11 +37,11 @@ func NewLocksScraper() Scraper {
 	}
 }
 
-func (c *locksScraper) Name() string {
+func (*locksScraper) Name() string {
 	return "LocksScraper"
 }
 
-func (c *locksScraper) Scrape(ctx context.Context, conn *pgx.Conn, version Version, ch chan<- prometheus.Metric) error {
+func (c *locksScraper) Scrape(ctx context.Context, conn *pgx.Conn, _ Version, ch chan<- prometheus.Metric) error {
 	rows, err := conn.Query(ctx, locksQuery)
 	if err != nil {
 		return err

collector/stat_activity.go

@@ -108,11 +108,11 @@ func NewStatActivityScraper() Scraper {
 	}
 }
 
-func (c *statActivityScraper) Name() string {
+func (*statActivityScraper) Name() string {
 	return "StatActivityScraper"
 }
 
-func (c *statActivityScraper) Scrape(ctx context.Context, conn *pgx.Conn, version Version, ch chan<- prometheus.Metric) error {
+func (c *statActivityScraper) Scrape(ctx context.Context, conn *pgx.Conn, _ Version, ch chan<- prometheus.Metric) error {
 	rows, err := conn.Query(ctx, statActivityQuery)
 	if err != nil {
 		return err

collector/stat_archiver.go

@@ -47,11 +47,11 @@ func NewStatArchiverScraper() Scraper {
 	}
 }
 
-func (c *statArchiverScraper) Name() string {
+func (*statArchiverScraper) Name() string {
 	return "StatArchiverScraper"
 }
 
-func (c *statArchiverScraper) Scrape(ctx context.Context, db *pgx.Conn, version Version, ch chan<- prometheus.Metric) error {
+func (c *statArchiverScraper) Scrape(ctx context.Context, db *pgx.Conn, _ Version, ch chan<- prometheus.Metric) error {
 	var archivedCount, failedCount int64
 	var statsReset time.Time
 

collector/stat_bgwriter.go

@@ -111,11 +111,11 @@ func NewStatBgwriterScraper() Scraper {
 	}
 }
 
-func (c *statBgwriterScraper) Name() string {
+func (*statBgwriterScraper) Name() string {
 	return "StatBgwriterScraper"
 }
 
-func (c *statBgwriterScraper) Scrape(ctx context.Context, conn *pgx.Conn, version Version, ch chan<- prometheus.Metric) error {
+func (c *statBgwriterScraper) Scrape(ctx context.Context, conn *pgx.Conn, _ Version, ch chan<- prometheus.Metric) error {
 	var checkpointsTimedCounter, checkpointsReqCounter,
 		buffersCheckpoint, buffersClean, maxWrittenClean,
 		buffersBackend, buffersBackendFsync, buffersAlloc int64

collector/stat_database.go

@@ -150,11 +150,11 @@ func NewStatDatabaseScraper() Scraper {
 	}
 }
 
-func (c *statDatabaseScraper) Name() string {
+func (*statDatabaseScraper) Name() string {
 	return "StatDatabaseScraper"
 }
 
-func (c *statDatabaseScraper) Scrape(ctx context.Context, conn *pgx.Conn, version Version, ch chan<- prometheus.Metric) error {
+func (c *statDatabaseScraper) Scrape(ctx context.Context, conn *pgx.Conn, _ Version, ch chan<- prometheus.Metric) error {
 	rows, err := conn.Query(ctx, statDatabaseQuery)
 	if err != nil {
 		return err

collector/stat_progress_vacuum.go

@@ -8,6 +8,10 @@ import (
 )
 
 const (
+	// metricEnabled represent the value used when a metrics state is
+	// active/enabled
+	metricEnabled = 1.0
+
 	// Scrape query
 	statVacuumProgress = `
 SELECT V.pid::text
@@ -135,11 +139,11 @@ func NewStatVacuumProgressScraper() Scraper {
 	}
 }
 
-func (c *statVacuumProgressScraper) Name() string {
+func (*statVacuumProgressScraper) Name() string {
 	return "StatVacuumProgressScraper"
 }
 
-func (c *statVacuumProgressScraper) Scrape(ctx context.Context, conn *pgx.Conn, version Version, ch chan<- prometheus.Metric) error {
+func (c *statVacuumProgressScraper) Scrape(ctx context.Context, conn *pgx.Conn, _ Version, ch chan<- prometheus.Metric) error {
 	rows, err := conn.Query(ctx, statVacuumProgress)
 	if err != nil {
 		return err
@@ -166,30 +170,38 @@ func (c *statVacuumProgressScraper) Scrape(ctx context.Context, conn *pgx.Conn,
 		}
 
 		// postgres_stat_vacuum_progress_running
-		ch <- prometheus.MustNewConstMetric(c.running, prometheus.GaugeValue, 1, pid, queryStart, schemaname, datname, relname)
+		ch <- prometheus.MustNewConstMetric(c.running, prometheus.GaugeValue, metricEnabled,
+			pid, queryStart, schemaname, datname, relname)
 
 		switch phase {
 		case "initializing":
 			// postgres_stat_vacuum_progress_phase_initializing
-			ch <- prometheus.MustNewConstMetric(c.phaseInitializing, prometheus.GaugeValue, 1, pid, queryStart, schemaname, datname, relname)
+			ch <- prometheus.MustNewConstMetric(c.phaseInitializing, prometheus.GaugeValue, metricEnabled,
+				pid, queryStart, schemaname, datname, relname)
 		case "scanning heap":
 			// postgres_stat_vacuum_progress_phase_scanning_heap
-			ch <- prometheus.MustNewConstMetric(c.phaseScanningHeap, prometheus.GaugeValue, 1, pid, queryStart, schemaname, datname, relname)
+			ch <- prometheus.MustNewConstMetric(c.phaseScanningHeap, prometheus.GaugeValue, metricEnabled,
+				pid, queryStart, schemaname, datname, relname)
 		case "vacuuming indexes":
 			// postgres_stat_vacuum_progress_phase_vacuuming_indexes
-			ch <- prometheus.MustNewConstMetric(c.phaseVacuumingIndexes, prometheus.GaugeValue, 1, pid, queryStart, schemaname, datname, relname)
+			ch <- prometheus.MustNewConstMetric(c.phaseVacuumingIndexes, prometheus.GaugeValue, metricEnabled,
+				pid, queryStart, schemaname, datname, relname)
 		case "vacuuming heap":
 			// postgres_stat_vacuum_progress_phase_vacuuming_heap
-			ch <- prometheus.MustNewConstMetric(c.phaseVacuumingHeap, prometheus.GaugeValue, 1, pid, queryStart, schemaname, datname, relname)
+			ch <- prometheus.MustNewConstMetric(c.phaseVacuumingHeap, prometheus.GaugeValue, metricEnabled,
+				pid, queryStart, schemaname, datname, relname)
 		case "cleaning up indexes":
 			// postgres_stat_vacuum_progress_phase_cleaning_up_indexes
-			ch <- prometheus.MustNewConstMetric(c.phaseCleaningUpIndexes, prometheus.GaugeValue, 1, pid, queryStart, schemaname, datname, relname)
+			ch <- prometheus.MustNewConstMetric(c.phaseCleaningUpIndexes, prometheus.GaugeValue, metricEnabled,
+				pid, queryStart, schemaname, datname, relname)
 		case "truncating heap":
 			// postgres_stat_vacuum_progress_phase_truncating_heap
-			ch <- prometheus.MustNewConstMetric(c.phaseTruncatingHeap, prometheus.GaugeValue, 1, pid, queryStart, schemaname, datname, relname)
+			ch <- prometheus.MustNewConstMetric(c.phaseTruncatingHeap, prometheus.GaugeValue, metricEnabled,
+				pid, queryStart, schemaname, datname, relname)
 		case "performing final cleanup":
 			// postgres_stat_vacuum_progress_phase_performing_final_cleanup
-			ch <- prometheus.MustNewConstMetric(c.phasePerformingFinalCleanup, prometheus.GaugeValue, 1, pid, queryStart, schemaname, datname, relname)
+			ch <- prometheus.MustNewConstMetric(c.phasePerformingFinalCleanup, prometheus.GaugeValue, metricEnabled,
+				pid, queryStart, schemaname, datname, relname)
 		}
 
 		// postgres_stat_vacuum_progress_heap_blks_total