feat(db): add ApplicationName to connection configuration

* Introduced ApplicationName field to identify clients in DSN
* Set default ApplicationName to "ResolveSpec"
* Updated tests for ApplicationName handling in DSN

pkg/config/dbmanager.go

@@ -55,6 +55,10 @@ type DBConnectionConfig struct {
 	SSLMode string `mapstructure:"sslmode"` // disable, require, verify-ca, verify-full
 	Schema  string `mapstructure:"schema"`  // Default schema
 
+	// ApplicationName identifies this client to the server (postgres
+	// application_name, mssql app name, mongodb appName)
+	ApplicationName string `mapstructure:"application_name"`
+
 	// SQLite specific
 	FilePath string `mapstructure:"filepath"`
 

pkg/dbmanager/README.md

@@ -271,6 +271,7 @@ db, _ := mgr.GetDefaultDatabase()
 | `database` | string | Database name |
 | `sslmode` | string | SSL mode (postgres/mssql): `disable`, `require`, etc. |
 | `schema` | string | Default schema (postgres/mssql) |
+| `application_name` | string | Client name shown by the server (postgres `application_name`, mssql `app name`, mongodb `appName`); defaults to `ResolveSpec` |
 | `filepath` | string | File path (sqlite only) |
 | `auth_source` | string | Auth source (mongodb) |
 | `replica_set` | string | Replica set name (mongodb) |

pkg/dbmanager/config.go

@@ -72,6 +72,9 @@ type ManagerConfig struct {
 	EnableAutoReconnect bool `mapstructure:"enable_auto_reconnect"`
 }
 
+// DefaultApplicationName is used when a connection does not set ApplicationName.
+const DefaultApplicationName = "ResolveSpec"
+
 // ConnectionConfig defines configuration for a single database connection
 type ConnectionConfig struct {
 	// Name is the unique name of this connection
@@ -95,6 +98,10 @@ type ConnectionConfig struct {
 	SSLMode string `mapstructure:"sslmode"` // disable, require, verify-ca, verify-full
 	Schema  string `mapstructure:"schema"`  // Default schema
 
+	// ApplicationName identifies this client to the server (postgres
+	// application_name, mssql app name, mongodb appName)
+	ApplicationName string `mapstructure:"application_name"`
+
 	// SQLite specific
 	FilePath string `mapstructure:"filepath"`
 
@@ -225,6 +232,10 @@ func (cc *ConnectionConfig) ApplyDefaults(global *ManagerConfig) {
 		cc.ConnMaxIdleTime = &idleTime
 	}
 
+	if cc.ApplicationName == "" {
+		cc.ApplicationName = DefaultApplicationName
+	}
+
 	// Default timeouts
 	if cc.ConnectTimeout == 0 {
 		cc.ConnectTimeout = 10 * time.Second
@@ -347,6 +358,9 @@ func (cc *ConnectionConfig) buildPostgresDSN() string {
 	if cc.Schema != "" {
 		q.Set("search_path", cc.Schema)
 	}
+	if cc.ApplicationName != "" {
+		q.Set("application_name", cc.ApplicationName)
+	}
 
 	u := url.URL{
 		Scheme:   "postgres",
@@ -405,6 +419,9 @@ func (cc *ConnectionConfig) buildMSSQLDSN() string {
 	if cc.Schema != "" {
 		q.Set("schema", cc.Schema)
 	}
+	if cc.ApplicationName != "" {
+		q.Set("app name", cc.ApplicationName)
+	}
 	if cc.ConnectTimeout > 0 {
 		sec := strconv.Itoa(int(cc.ConnectTimeout.Seconds()))
 		q.Set("connection timeout", sec)
@@ -437,6 +454,9 @@ func (cc *ConnectionConfig) buildMongoDSN() string {
 	if cc.ReadPreference != "" {
 		q.Set("readPreference", cc.ReadPreference)
 	}
+	if cc.ApplicationName != "" {
+		q.Set("appName", cc.ApplicationName)
+	}
 
 	u := url.URL{
 		Scheme:   "mongodb",
@@ -480,6 +500,7 @@ func FromConfig(cfg config.DBManagerConfig) ManagerConfig {
 			Database:        connCfg.Database,
 			SSLMode:         connCfg.SSLMode,
 			Schema:          connCfg.Schema,
+			ApplicationName: connCfg.ApplicationName,
 			FilePath:        connCfg.FilePath,
 			AuthSource:      connCfg.AuthSource,
 			ReplicaSet:      connCfg.ReplicaSet,
@@ -519,6 +540,7 @@ func (cc *ConnectionConfig) GetConnMaxIdleTime() *time.Duration { return cc.Conn
 func (cc *ConnectionConfig) GetQueryTimeout() time.Duration     { return cc.QueryTimeout }
 func (cc *ConnectionConfig) GetEnableMetrics() bool             { return cc.EnableMetrics }
 func (cc *ConnectionConfig) GetReadPreference() string          { return cc.ReadPreference }
+func (cc *ConnectionConfig) GetApplicationName() string         { return cc.ApplicationName }
 func (cc *ConnectionConfig) GetRetryAttempts() int              { return cc.RetryAttempts }
 func (cc *ConnectionConfig) GetRetryDelay() time.Duration       { return cc.RetryDelay }
 func (cc *ConnectionConfig) GetRetryMaxDelay() time.Duration    { return cc.RetryMaxDelay }

pkg/dbmanager/config_dsn_test.go

@@ -107,3 +107,33 @@ func TestSQLiteMemoryPoolPinned(t *testing.T) {
 		}
 	}
 }
+
+func TestApplicationNameInDSN(t *testing.T) {
+	cc := ConnectionConfig{Host: "h", Port: 1, Database: "d", ApplicationName: "my app&x=y"}
+	for name, c := range map[string]struct{ dsn, key string }{
+		"postgres": {cc.buildPostgresDSN(), "application_name"},
+		"mssql":    {cc.buildMSSQLDSN(), "app name"},
+		"mongo":    {cc.buildMongoDSN(), "appName"},
+	} {
+		u, err := url.Parse(c.dsn)
+		if err != nil {
+			t.Fatalf("%s: %v", name, err)
+		}
+		if got := u.Query().Get(c.key); got != cc.ApplicationName {
+			t.Errorf("%s: %s = %q, want %q", name, c.key, got, cc.ApplicationName)
+		}
+	}
+}
+
+func TestApplicationNameDefault(t *testing.T) {
+	cc := ConnectionConfig{Type: DatabaseTypePostgreSQL, Host: "h", Database: "d"}
+	cc.ApplyDefaults(nil)
+	if cc.ApplicationName != "ResolveSpec" {
+		t.Errorf("ApplicationName = %q, want ResolveSpec", cc.ApplicationName)
+	}
+	cc = ConnectionConfig{Type: DatabaseTypePostgreSQL, Host: "h", Database: "d", ApplicationName: "x"}
+	cc.ApplyDefaults(nil)
+	if cc.ApplicationName != "x" {
+		t.Errorf("explicit ApplicationName overwritten: %q", cc.ApplicationName)
+	}
+}

pkg/dbmanager/providers/pgconnector.go

@@ -123,6 +123,12 @@ func buildPGXConfig(cfg ConnectionConfig) (*pgx.ConnConfig, error) {
 	}
 
 	cc.DialFunc = newDialFunc(cfg.GetConnectTimeout())
+	// Also applies to caller-supplied DSNs that do not set application_name.
+	if name := cfg.GetApplicationName(); name != "" {
+		if _, set := cc.RuntimeParams["application_name"]; !set {
+			cc.RuntimeParams["application_name"] = name
+		}
+	}
 	if cfg.GetQueryTimeout() > 0 {
 		if _, set := cc.RuntimeParams["statement_timeout"]; !set {
 			cc.RuntimeParams["statement_timeout"] = fmt.Sprintf("%d", cfg.GetQueryTimeout().Milliseconds())

pkg/dbmanager/providers/provider.go

@@ -59,6 +59,7 @@ type ConnectionConfig interface {
 	GetConnMaxLifetime() *time.Duration
 	GetConnMaxIdleTime() *time.Duration
 	GetReadPreference() string
+	GetApplicationName() string
 	GetRetryAttempts() int
 	GetRetryDelay() time.Duration
 	GetRetryMaxDelay() time.Duration