fix: show valid log levels in help

internal/app/config.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"strings"
 
 	"github.com/hashicorp/terraform/command/cliconfig"
 	"github.com/leg100/pug/internal/logging"
@@ -53,11 +54,15 @@ func parse(stderr io.Writer, args []string) (config, error) {
 	fs.StringEnumVar(&cfg.FirstPage, 'f', "first-page", "The first page to open on startup.", "modules", "workspaces", "runs", "tasks", "logs")
 	fs.BoolVar(&cfg.Debug, 'd', "debug", "Log bubbletea messages to messages.log")
 	fs.BoolVar(&cfg.version, 'v', "version", "Print version.")
-	fs.StringEnumVar(&cfg.loggingOptions.Level, 'l', "log-level", "Logging level.", "info", "debug", "error", "warn")
 	_ = fs.String('c', "config", defaultConfigFile, "Path to config file.")
 
 	fs.BoolVar(&cfg.DisableReloadAfterApply, 0, "disable-reload-after-apply", "Disable automatic reload of state following an apply.")
 
+	{
+		usage := fmt.Sprintf("Logging level (valid: %s).", strings.Join(logging.ValidLevels(), ","))
+		fs.StringEnumVar(&cfg.loggingOptions.Level, 'l', "log-level", usage, logging.ValidLevels()...)
+	}
+
 	// Plugin cache is enabled not via pug flags but via terraform config
 	tfcfg, _ := cliconfig.LoadConfig()
 	cfg.PluginCache = (tfcfg.PluginCacheDir != "")

internal/app/config_test.go

@@ -1,6 +1,7 @@
 package app
 
 import (
+	"bytes"
 	"io"
 	"os"
 	"path/filepath"
@@ -177,3 +178,13 @@ func TestConfig(t *testing.T) {
 		})
 	}
 }
+
+func TestHelpFlag(t *testing.T) {
+	got := new(bytes.Buffer)
+	_, err := parse(got, []string{"--help"})
+	// Help flag should return error
+	require.Error(t, err)
+
+	want := "-l, --log-level STRING             Logging level (valid: info,debug,error,warn). (default: info)"
+	assert.Contains(t, got.String(), want)
+}

internal/logging/logger.go

@@ -3,16 +3,40 @@ package logging
 import (
 	"io"
 	"log/slog"
+	"slices"
 
 	"github.com/leg100/pug/internal/pubsub"
 	"github.com/leg100/pug/internal/resource"
+	"golang.org/x/exp/maps"
 )
 
+const DefaultLevel = "info"
+
 var levels = map[string]slog.Level{
-	"debug": slog.LevelDebug,
-	"info":  slog.LevelInfo,
-	"warn":  slog.LevelWarn,
-	"error": slog.LevelError,
+	"debug":      slog.LevelDebug,
+	DefaultLevel: slog.LevelInfo,
+	"warn":       slog.LevelWarn,
+	"error":      slog.LevelError,
+}
+
+// ValidLevels returns valid strings for choosing a log level. Returns the
+// default log level first.
+func ValidLevels() []string {
+	keys := maps.Keys(levels)
+	slices.SortFunc(keys, func(a, b string) int {
+		if a == DefaultLevel {
+			return -1
+		}
+		if b == DefaultLevel {
+			return 1
+		}
+		// Sort remaining in alphabetical order.
+		if a < b {
+			return -1
+		}
+		return 1
+	})
+	return keys
 }
 
 // NewLogger constructs Logger, a slog wrapper with additional functionality.