Initial

backend/internal/env/loader.go

@@ -0,0 +1,68 @@
+// Package env provides a minimal, dependency-free .env file loader.
+//
+// It reads KEY=VAL pairs from a file and sets them into the process
+// environment using os.Setenv, but only for variables that are NOT already
+// set. This gives the real environment (system env / shell) priority over
+// values in the .env file.
+package env
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+const DefaultPath = ".env"
+
+func LoadEnvDefault() error {
+	return LoadEnv(DefaultPath)
+}
+
+func LoadEnv(path string) error {
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+
+		key, value, ok := strings.Cut(line, "=")
+		if !ok {
+			continue
+		}
+		key = strings.TrimSpace(key)
+		if key == "" {
+			continue
+		}
+		value = strings.TrimSpace(value)
+		value = unquote(value)
+
+		if _, exists := os.LookupEnv(key); exists {
+			continue
+		}
+		if err := os.Setenv(key, value); err != nil {
+			return fmt.Errorf("failed to set env var %q: %w", key, err)
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return fmt.Errorf("failed to read %s: %w", path, err)
+	}
+	return nil
+}
+
+func unquote(value string) string {
+	if len(value) >= 2 {
+		first, last := value[0], value[len(value)-1]
+		if (first == '"' && last == '"') || (first == '\'' && last == '\'') {
+			return value[1 : len(value)-1]
+		}
+	}
+	return value
+}