feat: optional S3-compatible storage for uploaded images, instead of the local upload directory

internal/infrastructure/config/storageSettings.go

@@ -0,0 +1,114 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"slices"
+	"strconv"
+)
+
+const (
+	StorageDriverLocal = "local"
+	StorageDriverS3    = "s3"
+
+	DefaultStorageDriver = StorageDriverLocal
+	DefaultS3Region      = "us-east-1"
+	DefaultS3PathStyle   = "false"
+	DefaultS3TLS         = "true"
+	EnvStorageDriver     = "STORAGE_DRIVER"
+	envS3Bucket          = "S3_BUCKET"
+	envS3Region          = "S3_REGION"
+	envS3Endpoint        = "S3_ENDPOINT"
+	envS3AccessKeyID     = "S3_ACCESS_KEY_ID"
+	envS3SecretKey       = "S3_SECRET_ACCESS_KEY"
+	envS3KeyPrefix       = "S3_KEY_PREFIX"
+	envS3PathStyle       = "S3_PATH_STYLE"
+	envS3TLS             = "S3_TLS"
+)
+
+var s3RequiredEnvVars = []string{envS3Bucket}
+
+type S3Settings struct {
+	Bucket          string
+	Region          string
+	Endpoint        string
+	AccessKeyID     string
+	SecretAccessKey string
+	KeyPrefix       string
+	PathStyle       bool
+	TLS             bool
+}
+
+type StorageSettings struct {
+	Driver string
+	S3     S3Settings
+}
+
+func StorageRequiredEnvVars(driver string) []string {
+	if driver == StorageDriverS3 {
+		return slices.Clone(s3RequiredEnvVars)
+	}
+	return nil
+}
+
+func storageSettingsFromEnv() (StorageSettings, error) {
+	driver := envOrDefault(EnvStorageDriver, DefaultStorageDriver)
+	switch driver {
+	case StorageDriverLocal:
+		return StorageSettings{Driver: driver}, nil
+	case StorageDriverS3:
+		s3, err := s3SettingsFromEnv()
+		if err != nil {
+			return StorageSettings{}, err
+		}
+		return StorageSettings{Driver: driver, S3: s3}, nil
+	default:
+		return StorageSettings{}, fmt.Errorf("unsupported storage driver %q", driver)
+	}
+}
+
+func s3SettingsFromEnv() (S3Settings, error) {
+	if err := MissingEnvVarError(s3RequiredEnvVars, nonEmptyEnvLookup); err != nil {
+		return S3Settings{}, err
+	}
+	accessKeyID := os.Getenv(envS3AccessKeyID)
+	secretKey := os.Getenv(envS3SecretKey)
+	if accessKeyID != "" && secretKey == "" {
+		return S3Settings{}, fmt.Errorf("Environment variable %s is not set (it is required when %s is set)", envS3SecretKey, envS3AccessKeyID)
+	}
+	if secretKey != "" && accessKeyID == "" {
+		return S3Settings{}, fmt.Errorf("Environment variable %s is not set (it is required when %s is set)", envS3AccessKeyID, envS3SecretKey)
+	}
+	pathStyle, err := boolEnv(envS3PathStyle, DefaultS3PathStyle)
+	if err != nil {
+		return S3Settings{}, err
+	}
+	tls, err := boolEnv(envS3TLS, DefaultS3TLS)
+	if err != nil {
+		return S3Settings{}, err
+	}
+	return S3Settings{
+		Bucket:          os.Getenv(envS3Bucket),
+		Region:          envOrDefault(envS3Region, DefaultS3Region),
+		Endpoint:        os.Getenv(envS3Endpoint),
+		AccessKeyID:     accessKeyID,
+		SecretAccessKey: secretKey,
+		KeyPrefix:       os.Getenv(envS3KeyPrefix),
+		PathStyle:       pathStyle,
+		TLS:             tls,
+	}, nil
+}
+
+func nonEmptyEnvLookup(name string) (string, bool) {
+	value := os.Getenv(name)
+	return value, value != ""
+}
+
+func boolEnv(name string, fallback string) (bool, error) {
+	raw := envOrDefault(name, fallback)
+	value, err := strconv.ParseBool(raw)
+	if err != nil {
+		return false, fmt.Errorf("%s must be true or false, got %q", name, raw)
+	}
+	return value, nil
+}