Initial commit

config/config.go

@@ -0,0 +1,126 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+
+	"github.com/rs/zerolog"
+)
+
+// Environment variable names.
+const (
+	EnvLogLevel               = "LOG_LEVEL"
+	EnvResponseTimeout        = "RESPONSE_TIMEOUT"
+	EnvPanicOnUnexpectedError = "PANIC_ON_UNEXPECTED_ERROR"
+	EnvRootPath               = "ROOT_PATH"
+	EnvDirIndexingEnabled     = "DIR_INDEXING_ENABLED"
+)
+
+// Config holds the application configuration loaded from environment variables.
+type Config struct {
+	LogLevel               zerolog.Level // Logging level (debug, info, warn, error)
+	ResponseTimeout        int           // Timeout for responses in seconds
+	PanicOnUnexpectedError bool          // Panic on unexpected errors when visiting a URL
+	RootPath               string        // Path to serve files from
+	DirIndexingEnabled     bool          // Allow client to browse directories or not
+}
+
+var CONFIG Config //nolint:gochecknoglobals
+
+// parsePositiveInt parses and validates positive integer values.
+func parsePositiveInt(param, value string) (int, error) {
+	val, err := strconv.Atoi(value)
+	if err != nil {
+		return 0, ValidationError{
+			Param:  param,
+			Value:  value,
+			Reason: "must be a valid integer",
+		}
+	}
+	if val <= 0 {
+		return 0, ValidationError{
+			Param:  param,
+			Value:  value,
+			Reason: "must be positive",
+		}
+	}
+	return val, nil
+}
+
+func parseBool(param, value string) (bool, error) {
+	val, err := strconv.ParseBool(value)
+	if err != nil {
+		return false, ValidationError{
+			Param:  param,
+			Value:  value,
+			Reason: "cannot be converted to boolean",
+		}
+	}
+	return val, nil
+}
+
+// GetConfig loads and validates configuration from environment variables
+func GetConfig() *Config {
+	config := &Config{}
+
+	// Map of environment variables to their parsing functions
+	parsers := map[string]func(string) error{
+		EnvLogLevel: func(v string) error {
+			level, err := zerolog.ParseLevel(v)
+			if err != nil {
+				return ValidationError{
+					Param:  EnvLogLevel,
+					Value:  v,
+					Reason: "must be one of: debug, info, warn, error",
+				}
+			}
+			config.LogLevel = level
+			return nil
+		},
+		EnvResponseTimeout: func(v string) error {
+			val, err := parsePositiveInt(EnvResponseTimeout, v)
+			if err != nil {
+				return err
+			}
+			config.ResponseTimeout = val
+			return nil
+		},
+		EnvPanicOnUnexpectedError: func(v string) error {
+			val, err := parseBool(EnvPanicOnUnexpectedError, v)
+			if err != nil {
+				return err
+			}
+			config.PanicOnUnexpectedError = val
+			return nil
+		},
+		EnvRootPath: func(v string) error {
+			config.RootPath = v
+			return nil
+		},
+		EnvDirIndexingEnabled: func(v string) error {
+			val, err := parseBool(EnvDirIndexingEnabled, v)
+			if err != nil {
+				return err
+			}
+			config.DirIndexingEnabled = val
+			return nil
+		},
+	}
+
+	// Process each environment variable
+	for envVar, parser := range parsers {
+		value, ok := os.LookupEnv(envVar)
+		if !ok {
+			_, _ = fmt.Fprintf(os.Stderr, "Missing required environment variable: %s\n", envVar)
+			os.Exit(1)
+		}
+
+		if err := parser(value); err != nil {
+			_, _ = fmt.Fprintf(os.Stderr, "Configuration error: %v\n", err)
+			os.Exit(1)
+		}
+	}
+
+	return config
+}

config/errors.go

@@ -0,0 +1,14 @@
+package config
+
+import "fmt"
+
+// ValidationError represents a config validation error
+type ValidationError struct {
+	Param  string
+	Value  string
+	Reason string
+}
+
+func (e ValidationError) Error() string {
+	return fmt.Sprintf("invalid value '%s' for %s: %s", e.Value, e.Param, e.Reason)
+}