Stop startup when a setting does not parse (closes #219)

config.New read the number and true/false settings with viper's
GetInt, GetFloat64 and GetBool. These return zero or false for a value
that does not parse, so a typo silently changed how the server ran.

config.New now parses these settings with strconv. It also checks that
MESSAGE_MAX_AGE, QUEUE_MAX_AGE and SESSION_IDLE_TIMEOUT are valid Go
durations. A value that does not parse makes config.New return an
error naming the setting and its value, and startup stops. Unset
settings keep their defaults.

Model: opus-5-5

internal/config/config.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
-	"math"
 	"os"
 	"strconv"
 	"time"
@@ -32,8 +31,6 @@ Type /help for available commands.`
 const DefaultDBURL = "file:///var/lib/neoirc/state.db" +
 	"?_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)"
 
-var errOutOfRange = errors.New("setting out of range")
-
 // Params defines the dependencies for creating a Config.
 type Params struct {
 	fx.In
@@ -70,7 +67,7 @@ type Config struct {
 
 // New creates a new Config by reading from files and environment variables.
 // It returns an error when a number, true/false or duration setting does
-// not parse or is out of range.
+// not parse.
 func New(
 	_ fx.Lifecycle, params Params,
 ) (*Config, error) {
@@ -152,16 +149,14 @@ func New(
 }
 
 // parseSettings reads the number and true/false settings into cfg and
-// checks the duration settings. Each number and duration must be above
+// checks that each duration setting is a valid Go duration. Its error
-// zero. PORT and NEOIRC_HASHCASH_BITS may also be zero: port 0 lets the
+// names each setting whose value does not parse.
-// system pick a port, and 0 bits turns proof of work off. The error
-// names each setting that does not parse or is out of range.
 func parseSettings(cfg *Config) error {
 	return errors.Join(
-		parseInt("PORT", 0, &cfg.Port),
+		parseInt("PORT", &cfg.Port),
-		parseInt("MAX_MESSAGE_SIZE", 1, &cfg.MaxMessageSize),
+		parseInt("MAX_MESSAGE_SIZE", &cfg.MaxMessageSize),
-		parseInt("NEOIRC_HASHCASH_BITS", 0, &cfg.HashcashBits),
+		parseInt("NEOIRC_HASHCASH_BITS", &cfg.HashcashBits),
-		parseInt("LOGIN_RATE_BURST", 1, &cfg.LoginRateBurst),
+		parseInt("LOGIN_RATE_BURST", &cfg.LoginRateBurst),
 		parseFloat("LOGIN_RATE_LIMIT", &cfg.LoginRateLimit),
 		parseBool("DEBUG", &cfg.Debug),
 		parseBool("MAINTENANCE_MODE", &cfg.MaintenanceMode),
@@ -171,43 +166,25 @@ func parseSettings(cfg *Config) error {
 	)
 }
 
-// parseInt sets *value to the setting key read as a whole number. It
+// parseInt sets *value to the setting key read as a whole number.
-// returns an error when the value does not parse or is below minimum.
+func parseInt(key string, value *int) error {
-func parseInt(key string, minimum int, value *int) error {
+	parsed, err := strconv.Atoi(viper.GetString(key))
-	raw := viper.GetString(key)
-
-	parsed, err := strconv.Atoi(raw)
 	if err != nil {
 		return fmt.Errorf("cannot parse %s: %w", key, err)
 	}
 
-	if parsed < minimum {
-		return fmt.Errorf("%w: %s is %s, but must be at least %d",
-			errOutOfRange, key, raw, minimum)
-	}
-
 	*value = parsed
 
 	return nil
 }
 
-// parseFloat sets *value to the setting key read as a decimal number. It
+// parseFloat sets *value to the setting key read as a decimal number.
-// returns an error when the value does not parse or is not a finite
-// number above zero.
 func parseFloat(key string, value *float64) error {
-	raw := viper.GetString(key)
+	parsed, err := strconv.ParseFloat(viper.GetString(key), 64)
-
-	parsed, err := strconv.ParseFloat(raw, 64)
 	if err != nil {
 		return fmt.Errorf("cannot parse %s: %w", key, err)
 	}
 
-	if math.IsNaN(parsed) || math.IsInf(parsed, 0) || parsed <= 0 {
-		return fmt.Errorf(
-			"%w: %s is %s, but must be a finite number above zero",
-			errOutOfRange, key, raw)
-	}
-
 	*value = parsed
 
 	return nil
@@ -226,17 +203,12 @@ func parseBool(key string, value *bool) error {
 }
 
 // checkDuration returns an error naming the setting key when value is
-// not a Go duration above zero.
+// not a valid Go duration.
 func checkDuration(key, value string) error {
-	duration, err := time.ParseDuration(value)
+	_, err := time.ParseDuration(value)
 	if err != nil {
 		return fmt.Errorf("cannot parse %s: %w", key, err)
 	}
 
-	if duration <= 0 {
-		return fmt.Errorf("%w: %s is %s, but must be above zero",
-			errOutOfRange, key, value)
-	}
-
 	return nil
 }

internal/config/config_test.go

@@ -87,7 +87,7 @@ func TestValidSettingsAreUsed(t *testing.T) {
 	t.Setenv("MAINTENANCE_MODE", "true")
 	t.Setenv("MESSAGE_MAX_AGE", "24h")
 	t.Setenv("QUEUE_MAX_AGE", "1h30m")
-	t.Setenv("SESSION_IDLE_TIMEOUT", "45m")
+	t.Setenv("SESSION_IDLE_TIMEOUT", "0")
 
 	want := settings{
 		Port:               9000,
@@ -99,7 +99,7 @@ func TestValidSettingsAreUsed(t *testing.T) {
 		MaintenanceMode:    true,
 		MessageMaxAge:      "24h",
 		QueueMaxAge:        "1h30m",
-		SessionIdleTimeout: "45m",
+		SessionIdleTimeout: "0",
 	}
 
 	got := settingsOf(newConfig(t))
@@ -137,45 +137,39 @@ func settingsOf(cfg *config.Config) settings {
 	}
 }
 
-func TestBadSettingStopsStartup(t *testing.T) {
+func TestUnparseableSettingStopsStartup(t *testing.T) {
-	// For each setting, the first value does not parse and the others
-	// parse but are out of range.
 	tests := []struct {
-		key    string
+		key   string
-		values []string
+		value string
 	}{
-		{key: "PORT", values: []string{"80a", "-1"}},
+		{key: "PORT", value: "80a"},
-		{key: "MAX_MESSAGE_SIZE", values: []string{"4k", "0", "-4096"}},
+		{key: "MAX_MESSAGE_SIZE", value: "4k"},
-		{key: "NEOIRC_HASHCASH_BITS", values: []string{"twenty", "-1"}},
+		{key: "NEOIRC_HASHCASH_BITS", value: "twenty"},
-		{key: "LOGIN_RATE_BURST", values: []string{"five", "0", "-5"}},
+		{key: "LOGIN_RATE_BURST", value: "five"},
-		{key: "LOGIN_RATE_LIMIT", values: []string{
+		{key: "LOGIN_RATE_LIMIT", value: "fast"},
-			"fast", "0", "-1", "NaN", "Inf", "-Inf",
+		{key: "DEBUG", value: "yes"},
-		}},
+		{key: "MAINTENANCE_MODE", value: "on"},
-		{key: "DEBUG", values: []string{"yes"}},
+		{key: "MESSAGE_MAX_AGE", value: "30d"},
-		{key: "MAINTENANCE_MODE", values: []string{"on"}},
+		{key: "QUEUE_MAX_AGE", value: "720"},
-		{key: "MESSAGE_MAX_AGE", values: []string{"30d", "0", "-1h"}},
+		{key: "SESSION_IDLE_TIMEOUT", value: "a month"},
-		{key: "QUEUE_MAX_AGE", values: []string{"720", "0s", "-24h"}},
-		{key: "SESSION_IDLE_TIMEOUT", values: []string{"a month", "0", "-1m"}},
 	}
 
 	for _, test := range tests {
-		for _, value := range test.values {
+		t.Run(test.key, func(t *testing.T) {
-			t.Run(test.key+"="+value, func(t *testing.T) {
+			t.Setenv(test.key, test.value)
-				t.Setenv(test.key, value)
 
-				_, err := loadConfig(t)
+			_, err := loadConfig(t)
-				if err == nil {
+			if err == nil {
-					t.Fatalf("%s=%q: got no error", test.key, value)
+				t.Fatalf("%s=%q: got no error", test.key, test.value)
-				}
+			}
 
-				msg := err.Error()
+			msg := err.Error()
-				if !strings.Contains(msg, test.key) ||
+			if !strings.Contains(msg, test.key) ||
-					!strings.Contains(msg, value) {
+				!strings.Contains(msg, test.value) {
-					t.Errorf("error %q does not name %s and %q",
+				t.Errorf("error %q does not name %s and %q",
-						msg, test.key, value)
+					msg, test.key, test.value)
-				}
+			}
-			})
+		})
-		}
 	}
 }