feat: optional MySQL/MariaDB database driver for deployments that cannot use local SQLite

internal/infrastructure/config/databaseSettings.go

@@ -0,0 +1,122 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"slices"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	DatabaseDriverSQLite = "sqlite"
+	DatabaseDriverMySQL  = "mysql"
+
+	DefaultDatabaseDriver          = DatabaseDriverSQLite
+	DefaultDatabasePort            = "3306"
+	DefaultDatabaseTLS             = "false"
+	DefaultMaxOpenConns            = "10"
+	DefaultMaxIdleConns            = "5"
+	DefaultConnMaxLifetimeSeconds  = "300"
+	EnvDatabaseDriver              = "DB_DRIVER"
+	envDatabaseHost                = "DB_HOST"
+	envDatabasePort                = "DB_PORT"
+	envDatabaseUser                = "DB_USER"
+	envDatabasePassword            = "DB_PASSWORD"
+	envDatabaseName                = "DB_NAME"
+	envDatabaseTLS                 = "DB_TLS"
+	envDatabaseMaxOpenConns        = "DB_MAX_OPEN_CONNS"
+	envDatabaseMaxIdleConns        = "DB_MAX_IDLE_CONNS"
+	envDatabaseConnMaxLifetimeSecs = "DB_CONN_MAX_LIFETIME_SECONDS"
+)
+
+var mysqlRequiredEnvVars = []string{envDatabaseHost, envDatabaseUser, envDatabasePassword, envDatabaseName}
+
+var DatabaseTLSModes = []string{"false", "true", "skip-verify", "preferred"}
+
+type DatabaseSettings struct {
+	Driver          string
+	Host            string
+	Port            string
+	User            string
+	Password        string
+	Name            string
+	TLS             string
+	MaxOpenConns    int
+	MaxIdleConns    int
+	ConnMaxLifetime time.Duration
+}
+
+func DatabaseRequiredEnvVars(driver string) []string {
+	if driver == DatabaseDriverMySQL {
+		return slices.Clone(mysqlRequiredEnvVars)
+	}
+	return nil
+}
+
+func MissingEnvVarError(names []string, lookup func(string) (string, bool)) error {
+	for _, name := range names {
+		if _, isSet := lookup(name); !isSet {
+			return fmt.Errorf("Environment variable %s is not set", name)
+		}
+	}
+	return nil
+}
+
+func databaseDriverFromEnv() string {
+	return envOrDefault(EnvDatabaseDriver, DefaultDatabaseDriver)
+}
+
+func databaseSettingsFromEnv() (DatabaseSettings, error) {
+	driver := databaseDriverFromEnv()
+	if driver != DatabaseDriverMySQL {
+		return DatabaseSettings{Driver: driver}, nil
+	}
+
+	tls := envOrDefault(envDatabaseTLS, DefaultDatabaseTLS)
+	if !slices.Contains(DatabaseTLSModes, tls) {
+		return DatabaseSettings{}, fmt.Errorf("%s must be one of %s, got %q", envDatabaseTLS, strings.Join(DatabaseTLSModes, ", "), tls)
+	}
+	maxOpen, err := nonNegativeIntEnv(envDatabaseMaxOpenConns, DefaultMaxOpenConns)
+	if err != nil {
+		return DatabaseSettings{}, err
+	}
+	maxIdle, err := nonNegativeIntEnv(envDatabaseMaxIdleConns, DefaultMaxIdleConns)
+	if err != nil {
+		return DatabaseSettings{}, err
+	}
+	lifetimeSeconds, err := nonNegativeIntEnv(envDatabaseConnMaxLifetimeSecs, DefaultConnMaxLifetimeSeconds)
+	if err != nil {
+		return DatabaseSettings{}, err
+	}
+
+	return DatabaseSettings{
+		Driver:          driver,
+		Host:            os.Getenv(envDatabaseHost),
+		Port:            envOrDefault(envDatabasePort, DefaultDatabasePort),
+		User:            os.Getenv(envDatabaseUser),
+		Password:        os.Getenv(envDatabasePassword),
+		Name:            os.Getenv(envDatabaseName),
+		TLS:             tls,
+		MaxOpenConns:    maxOpen,
+		MaxIdleConns:    maxIdle,
+		ConnMaxLifetime: time.Duration(lifetimeSeconds) * time.Second,
+	}, nil
+}
+
+func envOrDefault(name string, fallback string) string {
+	if value := os.Getenv(name); value != "" {
+		return value
+	}
+	return fallback
+}
+
+func nonNegativeIntEnv(name string, fallback string) (int, error) {
+	raw := envOrDefault(name, fallback)
+	value, err := strconv.Atoi(raw)
+	if err != nil || value < 0 {
+		return 0, fmt.Errorf("%s must be a non-negative whole number, got %q", name, raw)
+	}
+	return value, nil
+}

internal/infrastructure/config/settings.go

@@ -28,6 +28,8 @@ type Settings struct {
 	UploadDir          string
 	JWTSecret          string
 	DBFile             string
+	Database           DatabaseSettings
+	DataDirPath        string
 	Port               string
 	Smtp               SmtpSettings
 	AuthRateLimit      AuthRateLimitSettings
@@ -38,6 +40,9 @@ type Settings struct {
 }
 
 func (s Settings) DataDir() string {
+	if s.DataDirPath != "" {
+		return s.DataDirPath
+	}
 	return filepath.Dir(s.DBFile)
 }
 
@@ -61,6 +66,11 @@ func NewSettingsFromEnv() (Settings, error) {
 		return Settings{}, err
 	}
 
+	database, err := databaseSettingsFromEnv()
+	if err != nil {
+		return Settings{}, err
+	}
+
 	return Settings{
 		Environment:        os.Getenv("ENVIRONMENT"),
 		CorsAllowedOrigins: parseSemicolonSeparatedList(os.Getenv("CORS_ALLOWED_ORIGINS")),
@@ -68,6 +78,8 @@ func NewSettingsFromEnv() (Settings, error) {
 		UploadDir:          os.Getenv("UPLOAD_DIR"),
 		JWTSecret:          os.Getenv("JWT_SECRET"),
 		DBFile:             os.Getenv("DB_FILE"),
+		Database:           database,
+		DataDirPath:        os.Getenv("DATA_DIR"),
 		Port:               os.Getenv("PORT"),
 		Smtp: SmtpSettings{
 			Login:    os.Getenv("SMTP_LOGIN"),