feat: runtime manager

lobby/internal/config/config.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"time"
 
+	"galaxy/lobby/internal/domain/engineimage"
 	"galaxy/lobby/internal/telemetry"
 	"galaxy/postgres"
 	"galaxy/redisconn"
@@ -49,6 +50,8 @@ const (
 	raceNameDirectoryBackendEnvVar  = "LOBBY_RACE_NAME_DIRECTORY_BACKEND"
 	raceNameExpirationIntervalEnvVar = "LOBBY_RACE_NAME_EXPIRATION_INTERVAL"
 
+	engineImageTemplateEnvVar = "LOBBY_ENGINE_IMAGE_TEMPLATE"
+
 	otelServiceNameEnvVar                 = "OTEL_SERVICE_NAME"
 	otelTracesExporterEnvVar              = "OTEL_TRACES_EXPORTER"
 	otelMetricsExporterEnvVar             = "OTEL_METRICS_EXPORTER"
@@ -78,6 +81,7 @@ const (
 	defaultGMTimeout                         = 5 * time.Second
 	defaultEnrollmentAutomationInterval      = 30 * time.Second
 	defaultRaceNameExpirationInterval        = time.Hour
+	defaultEngineImageTemplate               = "galaxy/game:" + engineimage.VersionPlaceholder
 	defaultOTelServiceName                   = "galaxy-lobby"
 
 	// RaceNameDirectoryBackendPostgres selects the PostgreSQL-backed
@@ -134,6 +138,9 @@ type Config struct {
 	// every pending_registration whose eligible_until has passed.
 	PendingRegistration PendingRegistrationConfig
 
+	// RuntimeManager configures the Runtime Manager publisher contract.
+	RuntimeManager RuntimeManagerConfig
+
 	// Telemetry configures the process-wide OpenTelemetry runtime.
 	Telemetry TelemetryConfig
 }
@@ -410,6 +417,27 @@ func (cfg PendingRegistrationConfig) Validate() error {
 	return nil
 }
 
+// RuntimeManagerConfig configures the Lobby-side Runtime Manager
+// publisher contract. Lobby resolves the Docker image reference it
+// publishes on `runtime:start_jobs` from a per-game
+// `target_engine_version` and the configured EngineImageTemplate.
+type RuntimeManagerConfig struct {
+	// EngineImageTemplate stores the Docker reference template applied
+	// to a game's `target_engine_version`. The string must contain the
+	// literal placeholder `{engine_version}`; Lobby fails fast at
+	// startup otherwise.
+	EngineImageTemplate string
+}
+
+// Validate reports whether cfg stores a usable Runtime Manager
+// publisher configuration.
+func (cfg RuntimeManagerConfig) Validate() error {
+	if _, err := engineimage.NewResolver(cfg.EngineImageTemplate); err != nil {
+		return fmt.Errorf("engine image template: %w", err)
+	}
+	return nil
+}
+
 // TelemetryConfig configures the Game Lobby Service OpenTelemetry runtime.
 type TelemetryConfig struct {
 	// ServiceName overrides the default OpenTelemetry service name.
@@ -504,6 +532,9 @@ func DefaultConfig() Config {
 		PendingRegistration: PendingRegistrationConfig{
 			Interval: defaultRaceNameExpirationInterval,
 		},
+		RuntimeManager: RuntimeManagerConfig{
+			EngineImageTemplate: defaultEngineImageTemplate,
+		},
 		Telemetry: TelemetryConfig{
 			ServiceName:     defaultOTelServiceName,
 			TracesExporter:  "none",