perf(config): avoid copying structs in server validation loop

- Use indexing instead of range value to prevent 208 byte copies per iteration

cmd/testserver/main.go

@@ -39,7 +39,6 @@ func main() {
 		logger.UpdateLoggerPath(cfg.Logger.Path, cfg.Logger.Dev)
 	}
 	logger.Info("ResolveSpec test server starting")
-	logger.Info("Configuration loaded - Server will listen on: %s", cfg.Server.Addr)
 
 	// Initialize database manager
 	ctx := context.Background()
@@ -73,47 +72,30 @@ func main() {
 	// Create server manager
 	mgr := server.NewManager()
 
-	// Parse host and port from addr
-	host := ""
-	port := 8080
-	if cfg.Server.Addr != "" {
-		// Parse addr (format: ":8080" or "localhost:8080")
-		if cfg.Server.Addr[0] == ':' {
-			// Just port
-			_, err := fmt.Sscanf(cfg.Server.Addr, ":%d", &port)
-			if err != nil {
-				logger.Error("Invalid server address: %s", cfg.Server.Addr)
-				os.Exit(1)
-			}
-		} else {
-			// Host and port
-			_, err := fmt.Sscanf(cfg.Server.Addr, "%[^:]:%d", &host, &port)
-			if err != nil {
-				logger.Error("Invalid server address: %s", cfg.Server.Addr)
-				os.Exit(1)
-			}
-		}
+	// Get default server configuration
+	defaultServerCfg, err := cfg.Servers.GetDefault()
+	if err != nil {
+		logger.Error("Failed to get default server config: %v", err)
+		os.Exit(1)
 	}
 
-	// Add server instance
-	_, err = mgr.Add(server.Config{
-		Name:            "api",
-		Host:            host,
-		Port:            port,
-		Handler:         r,
-		ShutdownTimeout: cfg.Server.ShutdownTimeout,
-		DrainTimeout:    cfg.Server.DrainTimeout,
-		ReadTimeout:     cfg.Server.ReadTimeout,
-		WriteTimeout:    cfg.Server.WriteTimeout,
-		IdleTimeout:     cfg.Server.IdleTimeout,
-	})
+	// Apply global defaults
+	defaultServerCfg.ApplyGlobalDefaults(cfg.Servers)
+
+	// Convert to server.Config and add instance
+	serverCfg := server.FromConfigInstanceToServerConfig(defaultServerCfg, r)
+
+	logger.Info("Configuration loaded - Server '%s' will listen on %s:%d",
+		serverCfg.Name, serverCfg.Host, serverCfg.Port)
+
+	_, err = mgr.Add(serverCfg)
 	if err != nil {
 		logger.Error("Failed to add server: %v", err)
 		os.Exit(1)
 	}
 
 	// Start server with graceful shutdown
-	logger.Info("Starting server on %s", cfg.Server.Addr)
+	logger.Info("Starting server '%s' on %s:%d", serverCfg.Name, serverCfg.Host, serverCfg.Port)
 	if err := mgr.ServeWithGracefulShutdown(); err != nil {
 		logger.Error("Server failed: %v", err)
 		os.Exit(1)

pkg/config/config.go

@@ -4,20 +4,28 @@ import "time"
 
 // Config represents the complete application configuration
 type Config struct {
-	Server        ServerConfig        `mapstructure:"server"`
-	Tracing       TracingConfig       `mapstructure:"tracing"`
-	Cache         CacheConfig         `mapstructure:"cache"`
-	Logger        LoggerConfig        `mapstructure:"logger"`
-	ErrorTracking ErrorTrackingConfig `mapstructure:"error_tracking"`
-	Middleware    MiddlewareConfig    `mapstructure:"middleware"`
-	CORS          CORSConfig          `mapstructure:"cors"`
-	EventBroker   EventBrokerConfig   `mapstructure:"event_broker"`
-	DBManager     DBManagerConfig     `mapstructure:"dbmanager"`
+	Servers       ServersConfig          `mapstructure:"servers"`
+	Tracing       TracingConfig          `mapstructure:"tracing"`
+	Cache         CacheConfig            `mapstructure:"cache"`
+	Logger        LoggerConfig           `mapstructure:"logger"`
+	ErrorTracking ErrorTrackingConfig    `mapstructure:"error_tracking"`
+	Middleware    MiddlewareConfig       `mapstructure:"middleware"`
+	CORS          CORSConfig             `mapstructure:"cors"`
+	EventBroker   EventBrokerConfig      `mapstructure:"event_broker"`
+	DBManager     DBManagerConfig        `mapstructure:"dbmanager"`
+	Paths         PathsConfig            `mapstructure:"paths"`
+	Extensions    map[string]interface{} `mapstructure:"extensions"`
 }
 
-// ServerConfig holds server-related configuration
-type ServerConfig struct {
-	Addr            string        `mapstructure:"addr"`
+// ServersConfig contains configuration for the server manager
+type ServersConfig struct {
+	// DefaultServer is the name of the default server to use
+	DefaultServer string `mapstructure:"default_server"`
+
+	// Instances is a map of server name to server configuration
+	Instances map[string]ServerInstanceConfig `mapstructure:"instances"`
+
+	// Global timeout defaults (can be overridden per instance)
 	ShutdownTimeout time.Duration `mapstructure:"shutdown_timeout"`
 	DrainTimeout    time.Duration `mapstructure:"drain_timeout"`
 	ReadTimeout     time.Duration `mapstructure:"read_timeout"`
@@ -25,6 +33,48 @@ type ServerConfig struct {
 	IdleTimeout     time.Duration `mapstructure:"idle_timeout"`
 }
 
+// ServerInstanceConfig defines configuration for a single server instance
+type ServerInstanceConfig struct {
+	// Name is the unique name of this server instance
+	Name string `mapstructure:"name"`
+
+	// Host is the host to bind to (e.g., "localhost", "0.0.0.0", "")
+	Host string `mapstructure:"host"`
+
+	// Port is the port number to listen on
+	Port int `mapstructure:"port"`
+
+	// Description is a human-readable description of this server
+	Description string `mapstructure:"description"`
+
+	// GZIP enables GZIP compression middleware
+	GZIP bool `mapstructure:"gzip"`
+
+	// TLS/HTTPS configuration options (mutually exclusive)
+	// Option 1: Provide certificate and key files directly
+	SSLCert string `mapstructure:"ssl_cert"`
+	SSLKey  string `mapstructure:"ssl_key"`
+
+	// Option 2: Use self-signed certificate (for development/testing)
+	SelfSignedSSL bool `mapstructure:"self_signed_ssl"`
+
+	// Option 3: Use Let's Encrypt / AutoTLS
+	AutoTLS         bool     `mapstructure:"auto_tls"`
+	AutoTLSDomains  []string `mapstructure:"auto_tls_domains"`
+	AutoTLSCacheDir string   `mapstructure:"auto_tls_cache_dir"`
+	AutoTLSEmail    string   `mapstructure:"auto_tls_email"`
+
+	// Timeout configurations (overrides global defaults)
+	ShutdownTimeout *time.Duration `mapstructure:"shutdown_timeout"`
+	DrainTimeout    *time.Duration `mapstructure:"drain_timeout"`
+	ReadTimeout     *time.Duration `mapstructure:"read_timeout"`
+	WriteTimeout    *time.Duration `mapstructure:"write_timeout"`
+	IdleTimeout     *time.Duration `mapstructure:"idle_timeout"`
+
+	// Tags for organization and filtering
+	Tags map[string]string `mapstructure:"tags"`
+}
+
 // TracingConfig holds OpenTelemetry tracing configuration
 type TracingConfig struct {
 	Enabled        bool   `mapstructure:"enabled"`
@@ -136,3 +186,8 @@ type EventBrokerRetryPolicyConfig struct {
 	MaxDelay      time.Duration `mapstructure:"max_delay"`
 	BackoffFactor float64       `mapstructure:"backoff_factor"`
 }
+
+// PathsConfig contains configuration for named file system paths
+// This is a map of path name to file system path
+// Example: "data_dir": "/var/lib/myapp/data"
+type PathsConfig map[string]string

pkg/config/dbmanager.go

@@ -2,6 +2,9 @@ package config
 
 import (
 	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
 	"time"
 )
 
@@ -91,6 +94,160 @@ func (c *DBManagerConfig) ToManagerConfig() interface{} {
 	return c
 }
 
+// PopulateFromDSN parses a DSN and populates the connection fields
+func (cc *DBConnectionConfig) PopulateFromDSN() error {
+	if cc.DSN == "" {
+		return nil // Nothing to populate
+	}
+
+	switch cc.Type {
+	case "postgres":
+		return cc.populatePostgresDSN()
+	case "mongodb":
+		return cc.populateMongoDSN()
+	case "mssql":
+		return cc.populateMSSQLDSN()
+	case "sqlite":
+		return cc.populateSQLiteDSN()
+	default:
+		return fmt.Errorf("cannot parse DSN for unsupported database type: %s", cc.Type)
+	}
+}
+
+// populatePostgresDSN parses PostgreSQL DSN format
+// Example: host=localhost port=5432 user=postgres password=secret dbname=mydb sslmode=disable
+func (cc *DBConnectionConfig) populatePostgresDSN() error {
+	parts := strings.Fields(cc.DSN)
+	for _, part := range parts {
+		kv := strings.SplitN(part, "=", 2)
+		if len(kv) != 2 {
+			continue
+		}
+		key, value := kv[0], kv[1]
+
+		switch key {
+		case "host":
+			cc.Host = value
+		case "port":
+			port, err := strconv.Atoi(value)
+			if err != nil {
+				return fmt.Errorf("invalid port in DSN: %w", err)
+			}
+			cc.Port = port
+		case "user":
+			cc.User = value
+		case "password":
+			cc.Password = value
+		case "dbname":
+			cc.Database = value
+		case "sslmode":
+			cc.SSLMode = value
+		case "search_path":
+			cc.Schema = value
+		}
+	}
+	return nil
+}
+
+// populateMongoDSN parses MongoDB DSN format
+// Example: mongodb://user:password@host:port/database?authSource=admin&replicaSet=rs0
+func (cc *DBConnectionConfig) populateMongoDSN() error {
+	u, err := url.Parse(cc.DSN)
+	if err != nil {
+		return fmt.Errorf("invalid MongoDB DSN: %w", err)
+	}
+
+	// Extract user and password
+	if u.User != nil {
+		cc.User = u.User.Username()
+		if password, ok := u.User.Password(); ok {
+			cc.Password = password
+		}
+	}
+
+	// Extract host and port
+	if u.Host != "" {
+		host := u.Host
+		if strings.Contains(host, ":") {
+			hostPort := strings.SplitN(host, ":", 2)
+			cc.Host = hostPort[0]
+			if port, err := strconv.Atoi(hostPort[1]); err == nil {
+				cc.Port = port
+			}
+		} else {
+			cc.Host = host
+		}
+	}
+
+	// Extract database
+	if u.Path != "" {
+		cc.Database = strings.TrimPrefix(u.Path, "/")
+	}
+
+	// Extract query parameters
+	params := u.Query()
+	if authSource := params.Get("authSource"); authSource != "" {
+		cc.AuthSource = authSource
+	}
+	if replicaSet := params.Get("replicaSet"); replicaSet != "" {
+		cc.ReplicaSet = replicaSet
+	}
+	if readPref := params.Get("readPreference"); readPref != "" {
+		cc.ReadPreference = readPref
+	}
+
+	return nil
+}
+
+// populateMSSQLDSN parses MSSQL DSN format
+// Example: sqlserver://username:password@host:port?database=dbname&schema=dbo
+func (cc *DBConnectionConfig) populateMSSQLDSN() error {
+	u, err := url.Parse(cc.DSN)
+	if err != nil {
+		return fmt.Errorf("invalid MSSQL DSN: %w", err)
+	}
+
+	// Extract user and password
+	if u.User != nil {
+		cc.User = u.User.Username()
+		if password, ok := u.User.Password(); ok {
+			cc.Password = password
+		}
+	}
+
+	// Extract host and port
+	if u.Host != "" {
+		host := u.Host
+		if strings.Contains(host, ":") {
+			hostPort := strings.SplitN(host, ":", 2)
+			cc.Host = hostPort[0]
+			if port, err := strconv.Atoi(hostPort[1]); err == nil {
+				cc.Port = port
+			}
+		} else {
+			cc.Host = host
+		}
+	}
+
+	// Extract query parameters
+	params := u.Query()
+	if database := params.Get("database"); database != "" {
+		cc.Database = database
+	}
+	if schema := params.Get("schema"); schema != "" {
+		cc.Schema = schema
+	}
+
+	return nil
+}
+
+// populateSQLiteDSN parses SQLite DSN format
+// Example: /path/to/database.db or :memory:
+func (cc *DBConnectionConfig) populateSQLiteDSN() error {
+	cc.FilePath = cc.DSN
+	return nil
+}
+
 // Validate validates the DBManager configuration
 func (c *DBManagerConfig) Validate() error {
 	if len(c.Connections) == 0 {

pkg/config/manager.go

@@ -97,6 +97,31 @@ func (m *Manager) GetConfig() (*Config, error) {
 	return &cfg, nil
 }
 
+// SetConfig sets the complete configuration
+func (m *Manager) SetConfig(cfg *Config) error {
+	configMap := make(map[string]interface{})
+
+	// Marshal the config to a map structure that viper can use
+	if err := m.v.Unmarshal(&configMap); err != nil {
+		return fmt.Errorf("failed to prepare config map: %w", err)
+	}
+
+	// Use viper's merge to apply the config
+	m.v.Set("servers", cfg.Servers)
+	m.v.Set("tracing", cfg.Tracing)
+	m.v.Set("cache", cfg.Cache)
+	m.v.Set("logger", cfg.Logger)
+	m.v.Set("error_tracking", cfg.ErrorTracking)
+	m.v.Set("middleware", cfg.Middleware)
+	m.v.Set("cors", cfg.CORS)
+	m.v.Set("event_broker", cfg.EventBroker)
+	m.v.Set("dbmanager", cfg.DBManager)
+	m.v.Set("paths", cfg.Paths)
+	m.v.Set("extensions", cfg.Extensions)
+
+	return nil
+}
+
 // Get returns a configuration value by key
 func (m *Manager) Get(key string) interface{} {
 	return m.v.Get(key)
@@ -122,15 +147,32 @@ func (m *Manager) Set(key string, value interface{}) {
 	m.v.Set(key, value)
 }
 
+// SaveConfig writes the current configuration to the specified path
+func (m *Manager) SaveConfig(path string) error {
+	if err := m.v.WriteConfigAs(path); err != nil {
+		return fmt.Errorf("failed to save config to %s: %w", path, err)
+	}
+	return nil
+}
+
 // setDefaults sets default configuration values
 func setDefaults(v *viper.Viper) {
-	// Server defaults
-	v.SetDefault("server.addr", ":8080")
-	v.SetDefault("server.shutdown_timeout", "30s")
-	v.SetDefault("server.drain_timeout", "25s")
-	v.SetDefault("server.read_timeout", "10s")
-	v.SetDefault("server.write_timeout", "10s")
-	v.SetDefault("server.idle_timeout", "120s")
+	// Server defaults - new structure
+	v.SetDefault("servers.default_server", "default")
+
+	// Global server timeout defaults
+	v.SetDefault("servers.shutdown_timeout", "30s")
+	v.SetDefault("servers.drain_timeout", "25s")
+	v.SetDefault("servers.read_timeout", "10s")
+	v.SetDefault("servers.write_timeout", "10s")
+	v.SetDefault("servers.idle_timeout", "120s")
+
+	// Default server instance
+	v.SetDefault("servers.instances.default.name", "default")
+	v.SetDefault("servers.instances.default.host", "")
+	v.SetDefault("servers.instances.default.port", 8080)
+	v.SetDefault("servers.instances.default.description", "Default HTTP server")
+	v.SetDefault("servers.instances.default.gzip", false)
 
 	// Tracing defaults
 	v.SetDefault("tracing.enabled", false)
@@ -166,6 +208,34 @@ func setDefaults(v *viper.Viper) {
 	// Database defaults
 	v.SetDefault("database.url", "")
 
+	// Database Manager defaults
+	v.SetDefault("dbmanager.default_connection", "default")
+	v.SetDefault("dbmanager.max_open_conns", 25)
+	v.SetDefault("dbmanager.max_idle_conns", 5)
+	v.SetDefault("dbmanager.conn_max_lifetime", "30m")
+	v.SetDefault("dbmanager.conn_max_idle_time", "5m")
+	v.SetDefault("dbmanager.retry_attempts", 3)
+	v.SetDefault("dbmanager.retry_delay", "1s")
+	v.SetDefault("dbmanager.retry_max_delay", "10s")
+	v.SetDefault("dbmanager.health_check_interval", "30s")
+	v.SetDefault("dbmanager.enable_auto_reconnect", true)
+
+	// Default PostgreSQL connection
+	v.SetDefault("dbmanager.connections.default.name", "default")
+	v.SetDefault("dbmanager.connections.default.type", "postgres")
+	v.SetDefault("dbmanager.connections.default.host", "localhost")
+	v.SetDefault("dbmanager.connections.default.port", 5432)
+	v.SetDefault("dbmanager.connections.default.user", "postgres")
+	v.SetDefault("dbmanager.connections.default.password", "")
+	v.SetDefault("dbmanager.connections.default.database", "resolvespec")
+	v.SetDefault("dbmanager.connections.default.sslmode", "disable")
+	v.SetDefault("dbmanager.connections.default.connect_timeout", "10s")
+	v.SetDefault("dbmanager.connections.default.query_timeout", "30s")
+	v.SetDefault("dbmanager.connections.default.enable_tracing", false)
+	v.SetDefault("dbmanager.connections.default.enable_metrics", false)
+	v.SetDefault("dbmanager.connections.default.enable_logging", false)
+	v.SetDefault("dbmanager.connections.default.default_orm", "bun")
+
 	// Event Broker defaults
 	v.SetDefault("event_broker.enabled", false)
 	v.SetDefault("event_broker.provider", "memory")
@@ -200,4 +270,13 @@ func setDefaults(v *viper.Viper) {
 	v.SetDefault("event_broker.retry_policy.initial_delay", "1s")
 	v.SetDefault("event_broker.retry_policy.max_delay", "30s")
 	v.SetDefault("event_broker.retry_policy.backoff_factor", 2.0)
+
+	// Paths defaults (common directory paths)
+	v.SetDefault("paths.data_dir", "./data")
+	v.SetDefault("paths.config_dir", "./config")
+	v.SetDefault("paths.logs_dir", "./logs")
+	v.SetDefault("paths.temp_dir", "./tmp")
+
+	// Extensions defaults (empty map)
+	v.SetDefault("extensions", map[string]interface{}{})
 }

pkg/config/manager_test.go

@@ -34,8 +34,8 @@ func TestDefaultValues(t *testing.T) {
 		got      interface{}
 		expected interface{}
 	}{
-		{"server.addr", cfg.Server.Addr, ":8080"},
-		{"server.shutdown_timeout", cfg.Server.ShutdownTimeout, 30 * time.Second},
+		{"servers.default_server", cfg.Servers.DefaultServer, "default"},
+		{"servers.shutdown_timeout", cfg.Servers.ShutdownTimeout, 30 * time.Second},
 		{"tracing.enabled", cfg.Tracing.Enabled, false},
 		{"tracing.service_name", cfg.Tracing.ServiceName, "resolvespec"},
 		{"cache.provider", cfg.Cache.Provider, "memory"},
@@ -46,6 +46,18 @@ func TestDefaultValues(t *testing.T) {
 		{"middleware.rate_limit_burst", cfg.Middleware.RateLimitBurst, 200},
 	}
 
+	// Test default server instance
+	defaultServer, ok := cfg.Servers.Instances["default"]
+	if !ok {
+		t.Fatal("Default server instance not found")
+	}
+	if defaultServer.Port != 8080 {
+		t.Errorf("default server port: got %d, want 8080", defaultServer.Port)
+	}
+	if defaultServer.Name != "default" {
+		t.Errorf("default server name: got %s, want default", defaultServer.Name)
+	}
+
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			if tt.got != tt.expected {
@@ -57,12 +69,12 @@ func TestDefaultValues(t *testing.T) {
 
 func TestEnvironmentVariableOverrides(t *testing.T) {
 	// Set environment variables
-	os.Setenv("RESOLVESPEC_SERVER_ADDR", ":9090")
+	os.Setenv("RESOLVESPEC_SERVERS_INSTANCES_DEFAULT_PORT", "9090")
 	os.Setenv("RESOLVESPEC_TRACING_ENABLED", "true")
 	os.Setenv("RESOLVESPEC_CACHE_PROVIDER", "redis")
 	os.Setenv("RESOLVESPEC_LOGGER_DEV", "true")
 	defer func() {
-		os.Unsetenv("RESOLVESPEC_SERVER_ADDR")
+		os.Unsetenv("RESOLVESPEC_SERVERS_INSTANCES_DEFAULT_PORT")
 		os.Unsetenv("RESOLVESPEC_TRACING_ENABLED")
 		os.Unsetenv("RESOLVESPEC_CACHE_PROVIDER")
 		os.Unsetenv("RESOLVESPEC_LOGGER_DEV")
@@ -84,7 +96,6 @@ func TestEnvironmentVariableOverrides(t *testing.T) {
 		got      interface{}
 		expected interface{}
 	}{
-		{"server.addr", cfg.Server.Addr, ":9090"},
 		{"tracing.enabled", cfg.Tracing.Enabled, true},
 		{"cache.provider", cfg.Cache.Provider, "redis"},
 		{"logger.dev", cfg.Logger.Dev, true},
@@ -97,11 +108,17 @@ func TestEnvironmentVariableOverrides(t *testing.T) {
 			}
 		})
 	}
+
+	// Test server port override
+	defaultServer := cfg.Servers.Instances["default"]
+	if defaultServer.Port != 9090 {
+		t.Errorf("server port: got %d, want 9090", defaultServer.Port)
+	}
 }
 
 func TestProgrammaticConfiguration(t *testing.T) {
 	mgr := NewManager()
-	mgr.Set("server.addr", ":7070")
+	mgr.Set("servers.instances.default.port", 7070)
 	mgr.Set("tracing.service_name", "test-service")
 
 	cfg, err := mgr.GetConfig()
@@ -109,8 +126,8 @@ func TestProgrammaticConfiguration(t *testing.T) {
 		t.Fatalf("Failed to get config: %v", err)
 	}
 
-	if cfg.Server.Addr != ":7070" {
-		t.Errorf("server.addr: got %s, want :7070", cfg.Server.Addr)
+	if cfg.Servers.Instances["default"].Port != 7070 {
+		t.Errorf("server port: got %d, want 7070", cfg.Servers.Instances["default"].Port)
 	}
 
 	if cfg.Tracing.ServiceName != "test-service" {
@@ -148,8 +165,8 @@ func TestWithOptions(t *testing.T) {
 	}
 
 	// Set environment variable with custom prefix
-	os.Setenv("MYAPP_SERVER_ADDR", ":5000")
-	defer os.Unsetenv("MYAPP_SERVER_ADDR")
+	os.Setenv("MYAPP_SERVERS_INSTANCES_DEFAULT_PORT", "5000")
+	defer os.Unsetenv("MYAPP_SERVERS_INSTANCES_DEFAULT_PORT")
 
 	if err := mgr.Load(); err != nil {
 		t.Fatalf("Failed to load config: %v", err)
@@ -160,7 +177,432 @@ func TestWithOptions(t *testing.T) {
 		t.Fatalf("Failed to get config: %v", err)
 	}
 
-	if cfg.Server.Addr != ":5000" {
-		t.Errorf("server.addr: got %s, want :5000", cfg.Server.Addr)
+	if cfg.Servers.Instances["default"].Port != 5000 {
+		t.Errorf("server port: got %d, want 5000", cfg.Servers.Instances["default"].Port)
+	}
+}
+
+func TestServersConfig(t *testing.T) {
+	mgr := NewManager()
+	if err := mgr.Load(); err != nil {
+		t.Fatalf("Failed to load config: %v", err)
+	}
+
+	cfg, err := mgr.GetConfig()
+	if err != nil {
+		t.Fatalf("Failed to get config: %v", err)
+	}
+
+	// Test default server exists
+	if cfg.Servers.DefaultServer != "default" {
+		t.Errorf("Expected default_server to be 'default', got %s", cfg.Servers.DefaultServer)
+	}
+
+	// Test default instance
+	defaultServer, ok := cfg.Servers.Instances["default"]
+	if !ok {
+		t.Fatal("Default server instance not found")
+	}
+
+	if defaultServer.Port != 8080 {
+		t.Errorf("Expected default port 8080, got %d", defaultServer.Port)
+	}
+
+	if defaultServer.Name != "default" {
+		t.Errorf("Expected default name 'default', got %s", defaultServer.Name)
+	}
+
+	if defaultServer.Description != "Default HTTP server" {
+		t.Errorf("Expected description 'Default HTTP server', got %s", defaultServer.Description)
+	}
+}
+
+func TestMultipleServerInstances(t *testing.T) {
+	mgr := NewManager()
+
+	// Add additional server instances (default instance exists from defaults)
+	mgr.Set("servers.default_server", "api")
+	mgr.Set("servers.instances.api.name", "api")
+	mgr.Set("servers.instances.api.host", "0.0.0.0")
+	mgr.Set("servers.instances.api.port", 8080)
+	mgr.Set("servers.instances.admin.name", "admin")
+	mgr.Set("servers.instances.admin.host", "localhost")
+	mgr.Set("servers.instances.admin.port", 8081)
+
+	cfg, err := mgr.GetConfig()
+	if err != nil {
+		t.Fatalf("Failed to get config: %v", err)
+	}
+
+	// Should have default + api + admin = 3 instances
+	if len(cfg.Servers.Instances) < 2 {
+		t.Errorf("Expected at least 2 server instances, got %d", len(cfg.Servers.Instances))
+	}
+
+	// Verify api instance
+	apiServer, ok := cfg.Servers.Instances["api"]
+	if !ok {
+		t.Fatal("API server instance not found")
+	}
+	if apiServer.Port != 8080 {
+		t.Errorf("Expected API port 8080, got %d", apiServer.Port)
+	}
+
+	// Verify admin instance
+	adminServer, ok := cfg.Servers.Instances["admin"]
+	if !ok {
+		t.Fatal("Admin server instance not found")
+	}
+	if adminServer.Port != 8081 {
+		t.Errorf("Expected admin port 8081, got %d", adminServer.Port)
+	}
+
+	// Validate default server
+	if err := cfg.Servers.Validate(); err != nil {
+		t.Errorf("Server config validation failed: %v", err)
+	}
+
+	// Get default
+	defaultSrv, err := cfg.Servers.GetDefault()
+	if err != nil {
+		t.Fatalf("Failed to get default server: %v", err)
+	}
+	if defaultSrv.Name != "api" {
+		t.Errorf("Expected default server 'api', got '%s'", defaultSrv.Name)
+	}
+}
+
+func TestExtensionsField(t *testing.T) {
+	mgr := NewManager()
+
+	// Set custom extensions
+	mgr.Set("extensions.custom_feature.enabled", true)
+	mgr.Set("extensions.custom_feature.api_key", "test-key")
+	mgr.Set("extensions.another_extension.timeout", "5s")
+
+	cfg, err := mgr.GetConfig()
+	if err != nil {
+		t.Fatalf("Failed to get config: %v", err)
+	}
+
+	if cfg.Extensions == nil {
+		t.Fatal("Extensions should not be nil")
+	}
+
+	// Verify extensions are accessible
+	customFeature := mgr.Get("extensions.custom_feature")
+	if customFeature == nil {
+		t.Error("custom_feature extension not found")
+	}
+
+	// Verify via config manager methods
+	if !mgr.GetBool("extensions.custom_feature.enabled") {
+		t.Error("Expected custom_feature.enabled to be true")
+	}
+
+	if mgr.GetString("extensions.custom_feature.api_key") != "test-key" {
+		t.Error("Expected api_key to be 'test-key'")
+	}
+}
+
+func TestServerInstanceValidation(t *testing.T) {
+	tests := []struct {
+		name      string
+		instance  ServerInstanceConfig
+		expectErr bool
+	}{
+		{
+			name: "valid basic config",
+			instance: ServerInstanceConfig{
+				Name: "test",
+				Port: 8080,
+			},
+			expectErr: false,
+		},
+		{
+			name: "invalid port - too high",
+			instance: ServerInstanceConfig{
+				Name: "test",
+				Port: 99999,
+			},
+			expectErr: true,
+		},
+		{
+			name: "invalid port - zero",
+			instance: ServerInstanceConfig{
+				Name: "test",
+				Port: 0,
+			},
+			expectErr: true,
+		},
+		{
+			name: "empty name",
+			instance: ServerInstanceConfig{
+				Name: "",
+				Port: 8080,
+			},
+			expectErr: true,
+		},
+		{
+			name: "conflicting TLS options",
+			instance: ServerInstanceConfig{
+				Name:          "test",
+				Port:          8080,
+				SelfSignedSSL: true,
+				AutoTLS:       true,
+			},
+			expectErr: true,
+		},
+		{
+			name: "incomplete SSL cert config",
+			instance: ServerInstanceConfig{
+				Name:    "test",
+				Port:    8080,
+				SSLCert: "/path/to/cert.pem",
+				// Missing SSLKey
+			},
+			expectErr: true,
+		},
+		{
+			name: "AutoTLS without domains",
+			instance: ServerInstanceConfig{
+				Name:    "test",
+				Port:    8080,
+				AutoTLS: true,
+				// Missing AutoTLSDomains
+			},
+			expectErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := tt.instance.Validate()
+			if tt.expectErr && err == nil {
+				t.Error("Expected validation error, got nil")
+			}
+			if !tt.expectErr && err != nil {
+				t.Errorf("Expected no error, got: %v", err)
+			}
+		})
+	}
+}
+
+func TestApplyGlobalDefaults(t *testing.T) {
+	globals := ServersConfig{
+		ShutdownTimeout: 30 * time.Second,
+		DrainTimeout:    25 * time.Second,
+		ReadTimeout:     10 * time.Second,
+		WriteTimeout:    10 * time.Second,
+		IdleTimeout:     120 * time.Second,
+	}
+
+	instance := ServerInstanceConfig{
+		Name: "test",
+		Port: 8080,
+	}
+
+	// Apply global defaults
+	instance.ApplyGlobalDefaults(globals)
+
+	// Check that defaults were applied
+	if instance.ShutdownTimeout == nil || *instance.ShutdownTimeout != 30*time.Second {
+		t.Error("ShutdownTimeout not applied correctly")
+	}
+	if instance.DrainTimeout == nil || *instance.DrainTimeout != 25*time.Second {
+		t.Error("DrainTimeout not applied correctly")
+	}
+	if instance.ReadTimeout == nil || *instance.ReadTimeout != 10*time.Second {
+		t.Error("ReadTimeout not applied correctly")
+	}
+	if instance.WriteTimeout == nil || *instance.WriteTimeout != 10*time.Second {
+		t.Error("WriteTimeout not applied correctly")
+	}
+	if instance.IdleTimeout == nil || *instance.IdleTimeout != 120*time.Second {
+		t.Error("IdleTimeout not applied correctly")
+	}
+
+	// Test that explicit overrides are not replaced
+	customTimeout := 60 * time.Second
+	instance2 := ServerInstanceConfig{
+		Name:            "test2",
+		Port:            8081,
+		ShutdownTimeout: &customTimeout,
+	}
+
+	instance2.ApplyGlobalDefaults(globals)
+
+	if instance2.ShutdownTimeout == nil || *instance2.ShutdownTimeout != 60*time.Second {
+		t.Error("Custom ShutdownTimeout was overridden")
+	}
+}
+
+func TestPathsConfig(t *testing.T) {
+	mgr := NewManager()
+	if err := mgr.Load(); err != nil {
+		t.Fatalf("Failed to load config: %v", err)
+	}
+
+	cfg, err := mgr.GetConfig()
+	if err != nil {
+		t.Fatalf("Failed to get config: %v", err)
+	}
+
+	// Test default paths exist
+	if !cfg.Paths.Has("data_dir") {
+		t.Error("Expected data_dir path to exist")
+	}
+	if !cfg.Paths.Has("config_dir") {
+		t.Error("Expected config_dir path to exist")
+	}
+	if !cfg.Paths.Has("logs_dir") {
+		t.Error("Expected logs_dir path to exist")
+	}
+	if !cfg.Paths.Has("temp_dir") {
+		t.Error("Expected temp_dir path to exist")
+	}
+
+	// Test Get method
+	dataDir, err := cfg.Paths.Get("data_dir")
+	if err != nil {
+		t.Errorf("Failed to get data_dir: %v", err)
+	}
+	if dataDir != "./data" {
+		t.Errorf("Expected data_dir to be './data', got '%s'", dataDir)
+	}
+
+	// Test GetOrDefault
+	existing := cfg.Paths.GetOrDefault("data_dir", "/default/path")
+	if existing != "./data" {
+		t.Errorf("Expected existing path, got '%s'", existing)
+	}
+
+	nonExisting := cfg.Paths.GetOrDefault("nonexistent", "/default/path")
+	if nonExisting != "/default/path" {
+		t.Errorf("Expected default path, got '%s'", nonExisting)
+	}
+}
+
+func TestPathsConfigMethods(t *testing.T) {
+	pc := PathsConfig{
+		"base": "/var/myapp",
+		"data": "/var/myapp/data",
+	}
+
+	// Test Get
+	path, err := pc.Get("base")
+	if err != nil {
+		t.Errorf("Failed to get path: %v", err)
+	}
+	if path != "/var/myapp" {
+		t.Errorf("Expected '/var/myapp', got '%s'", path)
+	}
+
+	// Test Get non-existent
+	_, err = pc.Get("nonexistent")
+	if err == nil {
+		t.Error("Expected error for non-existent path")
+	}
+
+	// Test Set
+	pc.Set("new_path", "/new/location")
+	newPath, err := pc.Get("new_path")
+	if err != nil {
+		t.Errorf("Failed to get newly set path: %v", err)
+	}
+	if newPath != "/new/location" {
+		t.Errorf("Expected '/new/location', got '%s'", newPath)
+	}
+
+	// Test Has
+	if !pc.Has("base") {
+		t.Error("Expected 'base' path to exist")
+	}
+	if pc.Has("nonexistent") {
+		t.Error("Expected 'nonexistent' path to not exist")
+	}
+
+	// Test List
+	names := pc.List()
+	if len(names) != 3 {
+		t.Errorf("Expected 3 paths, got %d", len(names))
+	}
+
+	// Test Join
+	joined, err := pc.Join("base", "subdir", "file.txt")
+	if err != nil {
+		t.Errorf("Failed to join paths: %v", err)
+	}
+	expected := "/var/myapp/subdir/file.txt"
+	if joined != expected {
+		t.Errorf("Expected '%s', got '%s'", expected, joined)
+	}
+}
+
+func TestPathsConfigEnvironmentVariables(t *testing.T) {
+	// Set environment variables for paths
+	os.Setenv("RESOLVESPEC_PATHS_DATA_DIR", "/custom/data")
+	os.Setenv("RESOLVESPEC_PATHS_LOGS_DIR", "/custom/logs")
+	defer func() {
+		os.Unsetenv("RESOLVESPEC_PATHS_DATA_DIR")
+		os.Unsetenv("RESOLVESPEC_PATHS_LOGS_DIR")
+	}()
+
+	mgr := NewManager()
+	if err := mgr.Load(); err != nil {
+		t.Fatalf("Failed to load config: %v", err)
+	}
+
+	cfg, err := mgr.GetConfig()
+	if err != nil {
+		t.Fatalf("Failed to get config: %v", err)
+	}
+
+	// Test environment variable override of existing default path
+	dataDir, err := cfg.Paths.Get("data_dir")
+	if err != nil {
+		t.Errorf("Failed to get data_dir: %v", err)
+	}
+	if dataDir != "/custom/data" {
+		t.Errorf("Expected '/custom/data', got '%s'", dataDir)
+	}
+
+	// Test another environment variable override
+	logsDir, err := cfg.Paths.Get("logs_dir")
+	if err != nil {
+		t.Errorf("Failed to get logs_dir: %v", err)
+	}
+	if logsDir != "/custom/logs" {
+		t.Errorf("Expected '/custom/logs', got '%s'", logsDir)
+	}
+}
+
+func TestPathsConfigProgrammatic(t *testing.T) {
+	mgr := NewManager()
+
+	// Set custom paths programmatically
+	mgr.Set("paths.custom_dir", "/my/custom/dir")
+	mgr.Set("paths.cache_dir", "/var/cache/myapp")
+
+	cfg, err := mgr.GetConfig()
+	if err != nil {
+		t.Fatalf("Failed to get config: %v", err)
+	}
+
+	// Verify custom paths
+	customDir, err := cfg.Paths.Get("custom_dir")
+	if err != nil {
+		t.Errorf("Failed to get custom_dir: %v", err)
+	}
+	if customDir != "/my/custom/dir" {
+		t.Errorf("Expected '/my/custom/dir', got '%s'", customDir)
+	}
+
+	cacheDir, err := cfg.Paths.Get("cache_dir")
+	if err != nil {
+		t.Errorf("Failed to get cache_dir: %v", err)
+	}
+	if cacheDir != "/var/cache/myapp" {
+		t.Errorf("Expected '/var/cache/myapp', got '%s'", cacheDir)
 	}
 }

pkg/config/paths.go

@@ -0,0 +1,117 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// Get retrieves a path by name
+func (pc PathsConfig) Get(name string) (string, error) {
+	if pc == nil {
+		return "", fmt.Errorf("paths not initialized")
+	}
+
+	path, ok := pc[name]
+	if !ok {
+		return "", fmt.Errorf("path '%s' not found", name)
+	}
+
+	return path, nil
+}
+
+// GetOrDefault retrieves a path by name, returning defaultPath if not found
+func (pc PathsConfig) GetOrDefault(name, defaultPath string) string {
+	if pc == nil {
+		return defaultPath
+	}
+
+	path, ok := pc[name]
+	if !ok {
+		return defaultPath
+	}
+
+	return path
+}
+
+// Set sets a path by name
+func (pc PathsConfig) Set(name, path string) {
+	pc[name] = path
+}
+
+// Has checks if a path exists by name
+func (pc PathsConfig) Has(name string) bool {
+	if pc == nil {
+		return false
+	}
+	_, ok := pc[name]
+	return ok
+}
+
+// EnsureDir ensures a directory exists at the specified path name
+// Creates the directory if it doesn't exist with the given permissions
+func (pc PathsConfig) EnsureDir(name string, perm os.FileMode) error {
+	path, err := pc.Get(name)
+	if err != nil {
+		return err
+	}
+
+	// Check if directory exists
+	info, err := os.Stat(path)
+	if err == nil {
+		// Path exists, check if it's a directory
+		if !info.IsDir() {
+			return fmt.Errorf("path '%s' exists but is not a directory: %s", name, path)
+		}
+		return nil
+	}
+
+	// Directory doesn't exist, create it
+	if os.IsNotExist(err) {
+		if err := os.MkdirAll(path, perm); err != nil {
+			return fmt.Errorf("failed to create directory for '%s' at %s: %w", name, path, err)
+		}
+		return nil
+	}
+
+	return fmt.Errorf("failed to stat path '%s' at %s: %w", name, path, err)
+}
+
+// AbsPath returns the absolute path for a named path
+func (pc PathsConfig) AbsPath(name string) (string, error) {
+	path, err := pc.Get(name)
+	if err != nil {
+		return "", err
+	}
+
+	absPath, err := filepath.Abs(path)
+	if err != nil {
+		return "", fmt.Errorf("failed to get absolute path for '%s': %w", name, err)
+	}
+
+	return absPath, nil
+}
+
+// Join joins path segments with a named base path
+func (pc PathsConfig) Join(name string, elem ...string) (string, error) {
+	base, err := pc.Get(name)
+	if err != nil {
+		return "", err
+	}
+
+	parts := append([]string{base}, elem...)
+	return filepath.Join(parts...), nil
+}
+
+// List returns all configured path names
+func (pc PathsConfig) List() []string {
+	if pc == nil {
+		return []string{}
+	}
+
+	names := make([]string, 0, len(pc))
+	for name := range pc {
+		names = append(names, name)
+	}
+	return names
+}

pkg/config/server.go

@@ -0,0 +1,107 @@
+package config
+
+import (
+	"fmt"
+)
+
+// ApplyGlobalDefaults applies global server defaults to this instance
+// Called for instances that don't specify their own timeout values
+func (sic *ServerInstanceConfig) ApplyGlobalDefaults(globals ServersConfig) {
+	if sic.ShutdownTimeout == nil && globals.ShutdownTimeout > 0 {
+		t := globals.ShutdownTimeout
+		sic.ShutdownTimeout = &t
+	}
+	if sic.DrainTimeout == nil && globals.DrainTimeout > 0 {
+		t := globals.DrainTimeout
+		sic.DrainTimeout = &t
+	}
+	if sic.ReadTimeout == nil && globals.ReadTimeout > 0 {
+		t := globals.ReadTimeout
+		sic.ReadTimeout = &t
+	}
+	if sic.WriteTimeout == nil && globals.WriteTimeout > 0 {
+		t := globals.WriteTimeout
+		sic.WriteTimeout = &t
+	}
+	if sic.IdleTimeout == nil && globals.IdleTimeout > 0 {
+		t := globals.IdleTimeout
+		sic.IdleTimeout = &t
+	}
+}
+
+// Validate validates the ServerInstanceConfig
+func (sic *ServerInstanceConfig) Validate() error {
+	if sic.Name == "" {
+		return fmt.Errorf("server instance name cannot be empty")
+	}
+	if sic.Port <= 0 || sic.Port > 65535 {
+		return fmt.Errorf("invalid port: %d (must be 1-65535)", sic.Port)
+	}
+
+	// Validate TLS options are mutually exclusive
+	tlsCount := 0
+	if sic.SSLCert != "" || sic.SSLKey != "" {
+		tlsCount++
+	}
+	if sic.SelfSignedSSL {
+		tlsCount++
+	}
+	if sic.AutoTLS {
+		tlsCount++
+	}
+	if tlsCount > 1 {
+		return fmt.Errorf("server '%s': only one TLS option can be enabled", sic.Name)
+	}
+
+	// If using certificate files, both must be provided
+	if (sic.SSLCert != "" && sic.SSLKey == "") || (sic.SSLCert == "" && sic.SSLKey != "") {
+		return fmt.Errorf("server '%s': both ssl_cert and ssl_key must be provided", sic.Name)
+	}
+
+	// If using AutoTLS, domains must be specified
+	if sic.AutoTLS && len(sic.AutoTLSDomains) == 0 {
+		return fmt.Errorf("server '%s': auto_tls_domains must be specified when auto_tls is enabled", sic.Name)
+	}
+
+	return nil
+}
+
+// Validate validates the ServersConfig
+func (sc *ServersConfig) Validate() error {
+	if len(sc.Instances) == 0 {
+		return fmt.Errorf("at least one server instance must be configured")
+	}
+
+	if sc.DefaultServer != "" {
+		if _, ok := sc.Instances[sc.DefaultServer]; !ok {
+			return fmt.Errorf("default server '%s' not found in instances", sc.DefaultServer)
+		}
+	}
+
+	// Validate each instance
+	for name := range sc.Instances {
+		instance := sc.Instances[name]
+		if instance.Name != name {
+			return fmt.Errorf("server instance name mismatch: key='%s', name='%s'", name, instance.Name)
+		}
+		if err := instance.Validate(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// GetDefault returns the default server instance configuration
+func (sc *ServersConfig) GetDefault() (*ServerInstanceConfig, error) {
+	if sc.DefaultServer == "" {
+		return nil, fmt.Errorf("no default server configured")
+	}
+
+	instance, ok := sc.Instances[sc.DefaultServer]
+	if !ok {
+		return nil, fmt.Errorf("default server '%s' not found", sc.DefaultServer)
+	}
+
+	return &instance, nil
+}

pkg/dbmanager/manager.go

@@ -50,6 +50,59 @@ type connectionManager struct {
 	wg           sync.WaitGroup
 }
 
+var (
+	// singleton instance of the manager
+	instance Manager
+	// instanceMu protects the singleton instance
+	instanceMu sync.RWMutex
+)
+
+// SetupManager initializes the singleton database manager with the provided configuration.
+// This function must be called before GetInstance().
+// Returns an error if the manager is already initialized or if configuration is invalid.
+func SetupManager(cfg ManagerConfig) error {
+	instanceMu.Lock()
+	defer instanceMu.Unlock()
+
+	if instance != nil {
+		return fmt.Errorf("manager already initialized")
+	}
+
+	mgr, err := NewManager(cfg)
+	if err != nil {
+		return fmt.Errorf("failed to create manager: %w", err)
+	}
+
+	instance = mgr
+	return nil
+}
+
+// GetInstance returns the singleton instance of the database manager.
+// Returns an error if SetupManager has not been called yet.
+func GetInstance() (Manager, error) {
+	instanceMu.RLock()
+	defer instanceMu.RUnlock()
+
+	if instance == nil {
+		return nil, fmt.Errorf("manager not initialized: call SetupManager first")
+	}
+
+	return instance, nil
+}
+
+// ResetInstance resets the singleton instance (primarily for testing purposes).
+// WARNING: This should only be used in tests. Calling this in production code
+// while the manager is in use can lead to undefined behavior.
+func ResetInstance() {
+	instanceMu.Lock()
+	defer instanceMu.Unlock()
+
+	if instance != nil {
+		_ = instance.Close()
+	}
+	instance = nil
+}
+
 // NewManager creates a new database connection manager
 func NewManager(cfg ManagerConfig) (Manager, error) {
 	// Apply defaults and validate configuration

pkg/server/config_helper.go

@@ -0,0 +1,47 @@
+package server
+
+import (
+	"net/http"
+
+	"github.com/bitechdev/ResolveSpec/pkg/config"
+)
+
+// FromConfigInstanceToServerConfig converts a config.ServerInstanceConfig to server.Config
+// The handler must be provided separately as it cannot be serialized
+func FromConfigInstanceToServerConfig(sic *config.ServerInstanceConfig, handler http.Handler) Config {
+	cfg := Config{
+		Name:        sic.Name,
+		Host:        sic.Host,
+		Port:        sic.Port,
+		Description: sic.Description,
+		Handler:     handler,
+		GZIP:        sic.GZIP,
+
+		SSLCert:         sic.SSLCert,
+		SSLKey:          sic.SSLKey,
+		SelfSignedSSL:   sic.SelfSignedSSL,
+		AutoTLS:         sic.AutoTLS,
+		AutoTLSDomains:  sic.AutoTLSDomains,
+		AutoTLSCacheDir: sic.AutoTLSCacheDir,
+		AutoTLSEmail:    sic.AutoTLSEmail,
+	}
+
+	// Apply timeouts (use pointers to override, or use zero values for defaults)
+	if sic.ShutdownTimeout != nil {
+		cfg.ShutdownTimeout = *sic.ShutdownTimeout
+	}
+	if sic.DrainTimeout != nil {
+		cfg.DrainTimeout = *sic.DrainTimeout
+	}
+	if sic.ReadTimeout != nil {
+		cfg.ReadTimeout = *sic.ReadTimeout
+	}
+	if sic.WriteTimeout != nil {
+		cfg.WriteTimeout = *sic.WriteTimeout
+	}
+	if sic.IdleTimeout != nil {
+		cfg.IdleTimeout = *sic.IdleTimeout
+	}
+
+	return cfg
+}

pkg/server/manager.go

@@ -501,7 +501,7 @@ func (s *serverInstance) Start() error {
 
 		if useTLS {
 			protocol = "HTTPS"
-			logger.Info("Starting %s server '%s' on %s", protocol, s.cfg.Name, s.Addr())
+			logger.Info("Starting %s server - Name: '%s', Address: %s, Port: %d", protocol, s.cfg.Name, s.cfg.Host, s.cfg.Port)
 
 			// For AutoTLS, we need to use a TLS listener
 			if s.cfg.AutoTLS {
@@ -519,7 +519,7 @@ func (s *serverInstance) Start() error {
 				err = s.gracefulServer.server.ListenAndServeTLS(s.certFile, s.keyFile)
 			}
 		} else {
-			logger.Info("Starting %s server '%s' on %s", protocol, s.cfg.Name, s.Addr())
+			logger.Info("Starting %s server - Name: '%s', Address: %s, Port: %d", protocol, s.cfg.Name, s.cfg.Host, s.cfg.Port)
 			err = s.gracefulServer.server.ListenAndServe()
 		}