docs(readme): update help output example

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

.github/.release-please-manifest.json

@@ -1,3 +1,3 @@
 {
-  ".": "0.0.3"
+  ".": "0.0.6"
 }

.github/workflows/ci.yml

@@ -16,6 +16,24 @@ jobs:
       - name: Print version
         run: |
           ./bin/macos-battery-exporter -v
+          ./bin/macos-battery-exporter
+
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.21"
+          cache: false
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          version: v1.55
+        env:
+          VERBOSE: "true"
+          GOOS: "darwin"
 
   release-please:
     runs-on: ubuntu-latest
@@ -35,7 +53,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: actions/setup-go@v4
+      - uses: actions/setup-go@v5
         with:
           go-version: "1.21"
       - name: Run GoReleaser

.golangci.yml

@@ -0,0 +1,87 @@
+linters-settings:
+  funlen:
+    lines: 300
+    statements: 450
+  golint:
+    min-confidence: 0
+  govet:
+    enable-all: true
+    disable:
+      - fieldalignment
+      - shadow
+  lll:
+    line-length: 80
+    tab-width: 4
+  maligned:
+    suggest-new: true
+  misspell:
+    locale: US
+
+linters:
+  disable-all: true
+  enable:
+    - asciicheck
+    - bodyclose
+    - durationcheck
+    - errcheck
+    - errorlint
+    - exhaustive
+    - exportloopref
+    - funlen
+    - gochecknoinits
+    - goconst
+    - gocritic
+    - godot
+    - goimports
+    - gomodguard
+    - goprintffuncname
+    - gosec
+    - gosimple
+    - govet
+    - importas
+    - ineffassign
+    - lll
+    - misspell
+    - nakedret
+    - nilerr
+    - noctx
+    - nolintlint
+    - prealloc
+    - predeclared
+    - revive
+    - staticcheck
+    - typecheck
+    - unconvert
+    - unparam
+    - unused
+    - whitespace
+
+issues:
+  exclude:
+    - Using the variable on range scope `tt` in function literal
+    - Using the variable on range scope `tc` in function literal
+  exclude-rules:
+    - path: "_test\\.go"
+      linters:
+        - funlen
+        - dupl
+    - source: "^//go:generate "
+      linters:
+        - lll
+    - source: "`env:"
+      linters:
+        - lll
+    - source: "`json:"
+      linters:
+        - lll
+    - source: "`xml:"
+      linters:
+        - lll
+    - source: "`yaml:"
+      linters:
+        - lll
+
+run:
+  timeout: 2m
+  allow-parallel-runners: true
+  modules-download-mode: readonly

.goreleaser.yml

@@ -44,6 +44,6 @@ brews:
       system "#{bin}/macos-battery-exporter -v"
     repository:
       owner: jimeh
-      name: homebrew-macos-battery-exporter
+      name: homebrew-tap
       branch: main
       token: "{{ .Env.BREW_TAP_TOKEN }}"

CHANGELOG.md

@@ -1,5 +1,26 @@
 # Changelog
 
+## [0.0.6](https://github.com/jimeh/macos-battery-exporter/compare/v0.0.5...v0.0.6) (2023-12-21)
+
+
+### Bug Fixes
+
+* **output:** write log output to stderr by default instead of stdout ([7b2e98e](https://github.com/jimeh/macos-battery-exporter/commit/7b2e98e150f9ee6d630023879395df0912047667))
+
+## [0.0.5](https://github.com/jimeh/macos-battery-exporter/compare/v0.0.4...v0.0.5) (2023-12-16)
+
+
+### Features
+
+* **go:** rename prom package to suitable prombat ([436e4a4](https://github.com/jimeh/macos-battery-exporter/commit/436e4a4b01d96654b7012f795f2d305ca4084681))
+
+## [0.0.4](https://github.com/jimeh/macos-battery-exporter/compare/v0.0.3...v0.0.4) (2023-12-16)
+
+
+### Continuous Integration
+
+* **lint:** setup golangci-lint ([2ac3ecb](https://github.com/jimeh/macos-battery-exporter/commit/2ac3ecb555e0f6eea369516328f1f03da7d61251))
+
 ## [0.0.3](https://github.com/jimeh/macos-battery-exporter/compare/v0.0.2...v0.0.3) (2023-12-16)
 
 

README.md

@@ -10,14 +10,48 @@
 
 <p align="center">
   <a href="https://github.com/jimeh/macos-battery-exporter/releases"><img src="https://img.shields.io/github/v/tag/jimeh/macos-battery-exporter?label=release" alt="GitHub tag (latest SemVer)"></a>
+  <a href="https://pkg.go.dev/github.com/jimeh/macos-battery-exporter"><img src="https://img.shields.io/badge/%E2%80%8B-reference-387b97.svg?logo=go&logoColor=white" alt="Go Reference"></a>
   <a href="https://github.com/jimeh/macos-battery-exporter/issues"><img src="https://img.shields.io/github/issues-raw/jimeh/macos-battery-exporter.svg?style=flat&logo=github&logoColor=white" alt="GitHub issues"></a>
   <a href="https://github.com/jimeh/macos-battery-exporter/pulls"><img src="https://img.shields.io/github/issues-pr-raw/jimeh/macos-battery-exporter.svg?style=flat&logo=github&logoColor=white" alt="GitHub pull requests"></a>
   <a href="https://github.com/jimeh/macos-battery-exporter/blob/main/LICENSE"><img src="https://img.shields.io/github/license/jimeh/macos-battery-exporter.svg?style=flat" alt="License Status"></a>
 </p>
 
-A Prometheus exporter for macOS which exposes most useful details available from
+A Prometheus exporter for macOS battery information, exposing wide range of
-`ioreg`. Includes a lot more details than what `node_exporter` supports via it's
+details available from `ioreg` about batteries. Includes a lot more details than
-`node_power_supply_*` metrics.
+what `node_exporter` supports via its `node_power_supply_*` metrics.
+
+## Installation
+
+### Manually
+
+Binary releases are available on the
+[Releases](https://github.com/jimeh/macos-battery-exporter/releases) page.
+
+### Homebrew
+
+You can install it from the [`jimeh/tap`](https://github.com/jimeh/homebrew-tap)
+Tap:
+
+```bash
+brew install jimeh/tap/macos-battery-exporter
+```
+
+#### Service
+
+The homebrew formula has a service configuration, which can be started with:
+
+```bash
+brew services start macos-battery-exporter
+```
+
+After which battery metrics are available on
+[`http://localhost:9108/metrics`](http://localhost:9108/metrics).
+
+### Go
+
+```bash
+go install github.com/jimeh/macos-battery-exporter@latest
+```
 
 ## Usage
 
@@ -28,19 +62,22 @@ macos-battery-exporter -h
 ```
 
 ```
-Usage of bin/macos-battery-exporter:
+usage: macos-battery-exporter [<options>]
+
   -b string
-        Bind address to run server on (default "127.0.0.1")
+    	Bind address to run server on (default "127.0.0.1")
+  -d string
+    	Log output device (stderr or stdout) (default "stderr")
   -l string
-        Log level (default "info")
+    	Log level (default "info")
   -n string
-        Namespace for metrics (default "macos")
+    	Namespace for metrics (default "macos")
   -o string
-        Output file to write to in Prometheus format
+    	Output file to write to in Prometheus format
   -p int
-        Port to run server on (default 9108)
+    	Port to run server on (default 9108)
-  -s    Run as a Prometheus metrics server
+  -s	Run as a Prometheus metrics server
-  -v    Print version and exit
+  -v	Print version and exit
 ```
 
 ### Print to STDOUT
@@ -55,19 +92,22 @@ macos-battery-exporter
 macos_battery_cell_disconnect_count{serial="ZTMDHJEZ8JKMYVAJKU"} 0
 # HELP macos_battery_charge_rate_amps Current charge rate in Ah.
 # TYPE macos_battery_charge_rate_amps gauge
-macos_battery_charge_rate_amps{serial="ZTMDHJEZ8JKMYVAJKU"} -0.927
+macos_battery_charge_rate_amps{serial="ZTMDHJEZ8JKMYVAJKU"} -1.004
 # HELP macos_battery_charge_rate_watts Current charge rate in Wh.
 # TYPE macos_battery_charge_rate_watts gauge
-macos_battery_charge_rate_watts{serial="ZTMDHJEZ8JKMYVAJKU"} -10.297116
+macos_battery_charge_rate_watts{serial="ZTMDHJEZ8JKMYVAJKU"} -12.712648
+# HELP macos_battery_count Total number of batteries.
+# TYPE macos_battery_count gauge
+macos_battery_count 1
 # HELP macos_battery_current_capacity_amps Current charge capacity in Ah.
 # TYPE macos_battery_current_capacity_amps gauge
-macos_battery_current_capacity_amps{serial="ZTMDHJEZ8JKMYVAJKU"} 1.127
+macos_battery_current_capacity_amps{serial="ZTMDHJEZ8JKMYVAJKU"} 5.39
 # HELP macos_battery_current_capacity_watts Current charge capacity in Wh.
 # TYPE macos_battery_current_capacity_watts gauge
-macos_battery_current_capacity_watts{serial="ZTMDHJEZ8JKMYVAJKU"} 12.518716
+macos_battery_current_capacity_watts{serial="ZTMDHJEZ8JKMYVAJKU"} 68.24818
 # HELP macos_battery_current_percentage Current battery charge percentage.
 # TYPE macos_battery_current_percentage gauge
-macos_battery_current_percentage{serial="ZTMDHJEZ8JKMYVAJKU"} 18
+macos_battery_current_percentage{serial="ZTMDHJEZ8JKMYVAJKU"} 91
 # HELP macos_battery_cycle_count Current battery cycle count.
 # TYPE macos_battery_cycle_count counter
 macos_battery_cycle_count{serial="ZTMDHJEZ8JKMYVAJKU"} 15
@@ -76,7 +116,7 @@ macos_battery_cycle_count{serial="ZTMDHJEZ8JKMYVAJKU"} 15
 macos_battery_design_capacity_amps{serial="ZTMDHJEZ8JKMYVAJKU"} 6.249
 # HELP macos_battery_design_capacity_watts Design capacity in Wh.
 # TYPE macos_battery_design_capacity_watts gauge
-macos_battery_design_capacity_watts{serial="ZTMDHJEZ8JKMYVAJKU"} 69.413892
+macos_battery_design_capacity_watts{serial="ZTMDHJEZ8JKMYVAJKU"} 79.124838
 # HELP macos_battery_fully_charged Indicates if the battery is fully charged.
 # TYPE macos_battery_fully_charged gauge
 macos_battery_fully_charged{serial="ZTMDHJEZ8JKMYVAJKU"} 0
@@ -91,19 +131,19 @@ macos_battery_info{built_in="true",device_name="ayzo3hgs",serial="ZTMDHJEZ8JKMYV
 macos_battery_is_charging{serial="ZTMDHJEZ8JKMYVAJKU"} 0
 # HELP macos_battery_max_capacity_amps Design capacity in Ah.
 # TYPE macos_battery_max_capacity_amps gauge
-macos_battery_max_capacity_amps{serial="ZTMDHJEZ8JKMYVAJKU"} 6.262
+macos_battery_max_capacity_amps{serial="ZTMDHJEZ8JKMYVAJKU"} 6.271
 # HELP macos_battery_max_capacity_watts Design capacity in Wh.
 # TYPE macos_battery_max_capacity_watts gauge
-macos_battery_max_capacity_watts{serial="ZTMDHJEZ8JKMYVAJKU"} 69.558296
+macos_battery_max_capacity_watts{serial="ZTMDHJEZ8JKMYVAJKU"} 79.403402
 # HELP macos_battery_temperature_celsius Current battery temperature in °C.
 # TYPE macos_battery_temperature_celsius gauge
-macos_battery_temperature_celsius{serial="ZTMDHJEZ8JKMYVAJKU"} 30.47
+macos_battery_temperature_celsius{serial="ZTMDHJEZ8JKMYVAJKU"} 30.53
 # HELP macos_battery_time_remaining_seconds Estimated time remaining until battery is fully charged or discharged.
 # TYPE macos_battery_time_remaining_seconds gauge
-macos_battery_time_remaining_seconds{serial="ZTMDHJEZ8JKMYVAJKU"} 3540
+macos_battery_time_remaining_seconds{serial="ZTMDHJEZ8JKMYVAJKU"} 14040
 # HELP macos_battery_voltage_volts Current battery voltage in V.
 # TYPE macos_battery_voltage_volts gauge
-macos_battery_voltage_volts{serial="ZTMDHJEZ8JKMYVAJKU"} 11.108
+macos_battery_voltage_volts{serial="ZTMDHJEZ8JKMYVAJKU"} 12.662
 ```
 
 ### Write to File
@@ -121,3 +161,7 @@ macos-battery-exporter -s
 ```bash
 curl http://localhost:9108/metrics
 ```
+
+## License
+
+[MIT](https://github.com/jimeh/macos-battery-exporter/blob/main/LICENSE)

battery/battery.go

@@ -15,12 +15,12 @@ type Battery struct {
 	// BuiltIn indicates if the battery is built-in or not.
 	BuiltIn bool
 
-	// ChargeRateAmps is the current charge rate in mAh. Negative values indicate
+	// ChargeRateAmps is the current charge rate in mAh. Negative values
-	// discharge, positive values indicate charging.
+	// indicate discharge, positive values indicate charging.
 	ChargeRateAmps int64
 
-	// ChargeRateWatts is the current charge rate in mWh. Negative values indicate
+	// ChargeRateWatts is the current charge rate in mWh. Negative values
-	// discharge, positive values indicate charging.
+	// indicate discharge, positive values indicate charging.
 	ChargeRateWatts float64
 
 	// CurrentCapacityAmps is the current battery capacity in mAh.
@@ -76,6 +76,7 @@ type Battery struct {
 func newBattery(b *batteryRaw) *Battery {
 	volts := float64(b.Voltage) / 1000
 
+	//nolint:lll
 	return &Battery{
 		BatteryCellDisconnectCount: b.BatteryCellDisconnectCount,
 		BuiltIn:                    b.BuiltIn,
@@ -101,29 +102,31 @@ func newBattery(b *batteryRaw) *Battery {
 }
 
 func Get() (*Battery, error) {
-	batteriesRaw, err := getAllRaw()
+	raw, err := getAllRaw()
 	if err != nil {
 		return nil, err
 	}
 
-	return newBattery(batteriesRaw[0]), nil
+	return newBattery(raw[0]), nil
 }
 
 func GetAll() ([]*Battery, error) {
-	batteriesRaw, err := getAllRaw()
+	raw, err := getAllRaw()
 	if err != nil {
 		return nil, err
 	}
 
 	batteries := []*Battery{}
-	for _, b := range batteriesRaw {
+	for _, b := range raw {
 		batteries = append(batteries, newBattery(b))
 	}
 
 	return batteries, nil
 }
 
-// roundTo rounds a float64 to 'places' decimal places
+// roundTo rounds a float64 to 'places' decimal places.
+//
+//nolint:unparam
 func roundTo(value float64, places int) float64 {
 	shift := math.Pow(10, float64(places))
 	return math.Round(value*shift) / shift

main.go

@@ -5,104 +5,170 @@ package main
 import (
 	"flag"
 	"fmt"
-	"log"
+	"io"
 	"log/slog"
 	"os"
 	"strings"
 
-	"github.com/jimeh/macos-battery-exporter/prom"
+	"github.com/jimeh/macos-battery-exporter/prombat"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/expfmt"
 )
 
 var (
+	name    = "macos-battery-exporter"
 	version = "0.0.0-dev"
 	commit  = "unknown"
+)
 
-	outputFlag = flag.String(
+type configuration struct {
+	Output       string
+	Server       bool
+	Bind         string
+	Port         int
+	Namespace    string
+	LogLevel     string
+	LogDevice    string
+	PrintVersion bool
+}
+
+func configure() (*configuration, *flag.FlagSet, error) {
+	fs := flag.NewFlagSet(name, flag.ExitOnError)
+	fs.Usage = func() {
+		fmt.Fprintf(fs.Output(),
+			"usage: %s [<options>]\n\n", fs.Name(),
+		)
+		fs.PrintDefaults()
+	}
+
+	config := &configuration{}
+
+	fs.StringVar(&config.Output,
 		"o", "", "Output file to write to in Prometheus format",
 	)
-	serverFlag = flag.Bool("s", false, "Run as a Prometheus metrics server")
+	fs.BoolVar(&config.Server,
-	bindFlag   = flag.String(
+		"s", false, "Run as a Prometheus metrics server",
+	)
+	fs.StringVar(&config.Bind,
 		"b", "127.0.0.1", "Bind address to run server on",
 	)
-	portFlag      = flag.Int("p", 9108, "Port to run server on")
+	fs.IntVar(&config.Port, "p", 9108, "Port to run server on")
-	namespaceFlag = flag.String(
+	fs.StringVar(&config.Namespace,
-		"n", prom.DefaultNamespace, "Namespace for metrics",
+		"n", prombat.DefaultNamespace, "Namespace for metrics",
 	)
-	logLevelFlag = flag.String("l", "info", "Log level")
+	fs.StringVar(&config.LogLevel,
-	versionFlag  = flag.Bool("v", false, "Print version and exit")
+		"l", "info", "Log level",
-)
+	)
+	fs.StringVar(&config.LogDevice,
+		"d", "stderr", "Log output device (stderr or stdout)",
+	)
+	fs.BoolVar(&config.PrintVersion,
+		"v", false, "Print version and exit",
+	)
+
+	err := fs.Parse(os.Args[1:])
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return config, fs, nil
+}
 
 func main() {
 	if err := mainE(); err != nil {
-		log.Fatal(err)
+		slog.Error(err.Error())
+		os.Exit(1)
 	}
 }
 
 func mainE() error {
-	flag.Parse()
+	config, _, err := configure()
-
-	err := setupSLog(*logLevelFlag)
 	if err != nil {
 		return err
 	}
 
-	if *versionFlag {
+	err = setupSLog(config.LogDevice, config.LogLevel)
-		fmt.Printf("macos-battery-exporter %s (%s)\n", version, commit)
+	if err != nil {
+		return err
+	}
+
+	if config.PrintVersion {
+		fmt.Printf("%s %s (%s)\n", name, version, commit)
 		return nil
 	}
 
-	if *serverFlag {
+	if config.Server {
-		opts := prom.ServerOptions{
+		return runServer(config)
-			Bind: *bindFlag,
-			Port: *portFlag,
-		}
-
-		return prom.RunServer(
-			*namespaceFlag,
-			prometheus.DefaultRegisterer.(*prometheus.Registry),
-			opts,
-		)
 	}
 
-	registry := prometheus.NewRegistry()
+	metrics, err := renderMetrics(config)
-	err = registry.Register(prom.NewCollector(*namespaceFlag))
 	if err != nil {
 		return err
 	}
 
+	if config.Output != "" {
+		return writeToFile(metrics, config.Output)
+	}
+
+	fmt.Print(metrics)
+	return nil
+}
+
+func runServer(config *configuration) error {
+	opts := prombat.ServerOptions{
+		Bind: config.Bind,
+		Port: config.Port,
+	}
+
+	return prombat.RunServer(
+		config.Namespace,
+		prometheus.DefaultRegisterer.(*prometheus.Registry),
+		opts,
+	)
+}
+
+func renderMetrics(config *configuration) (string, error) {
+	registry := prometheus.NewRegistry()
+	err := registry.Register(prombat.NewCollector(config.Namespace))
+	if err != nil {
+		return "", err
+	}
+
 	gatherers := prometheus.Gatherers{registry}
 	metricFamilies, err := gatherers.Gather()
 	if err != nil {
-		return err
+		return "", err
 	}
 
 	var sb strings.Builder
 	for _, mf := range metricFamilies {
 		_, err := expfmt.MetricFamilyToText(&sb, mf)
 		if err != nil {
-			return err
+			return "", err
 		}
 	}
 
-	if *outputFlag != "" {
+	return sb.String(), nil
-		return writeToFile(sb.String(), *outputFlag)
-	} else {
-		fmt.Print(sb.String())
-	}
-
-	return nil
 }
 
-func setupSLog(levelStr string) error {
+func setupSLog(device string, levelStr string) error {
+	var w io.Writer
+	switch device {
+	case "stderr":
+		w = os.Stderr
+	case "stdout":
+		w = os.Stdout
+	default:
+		return fmt.Errorf("invalid log device: %s", device)
+	}
+
 	var level slog.Level
 	err := level.UnmarshalText([]byte(levelStr))
 	if err != nil {
 		return err
 	}
 
-	handler := slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
+	handler := slog.NewTextHandler(w, &slog.HandlerOptions{
 		Level: level,
 	})
 	logger := slog.New(handler)

prombat/collector.go

@@ -1,6 +1,6 @@
 //go:build darwin
 
-package prom
+package prombat
 
 import (
 	"log/slog"
@@ -367,7 +367,9 @@ func boolToFloat64(b bool) float64 {
 	return 0
 }
 
-// roundTo rounds a float64 to 'places' decimal places
+// roundTo rounds a float64 to 'places' decimal places.
+//
+//nolint:unparam
 func roundTo(value float64, places int) float64 {
 	shift := math.Pow(10, float64(places))
 	return math.Round(value*shift) / shift

prombat/server.go

@@ -1,6 +1,6 @@
 //go:build darwin
 
-package prom
+package prombat
 
 import (
 	"fmt"
@@ -14,23 +14,17 @@ import (
 
 const DefaultNamespace = "macos"
 
-type Registry interface {
-	prometheus.Registerer
-	prometheus.Gatherer
-}
-
 type ServerOptions struct {
 	Bind         string
 	Port         int
 	ReadTimeout  time.Duration
 	WriteTimeout time.Duration
 	IdleTimeout  time.Duration
-	Logger       *slog.Logger
 }
 
 type Server struct {
 	*http.Server
-	registry Registry
+	registry *prometheus.Registry
 	mux      *http.ServeMux
 }