Observability

Observability¶

Gember Event Sourcing provides built-in logging through decorator classes that wrap the core components. These decorators use PSR-3 for logging, making them compatible with any framework.

Logging¶

Three loggable decorators provide structured logging for the main execution paths:

Decorator	Wraps	Logs
`LoggableEventStoreDecorator`	`EventStore`	Event loading and appending
`LoggableUseCaseCommandExecutorDecorator`	`UseCaseCommandExecutor`	Command handling on use cases
`LoggableSagaEventExecutorDecorator`	`SagaEventExecutor`	Event handling on sagas

All decorators log at INFO level using PSR-3's LoggerInterface.

What gets logged¶

Each decorator logs the start, completion, and failure of its wrapped operation:

Event store (load/append):

[EventStore] Started loading events          {domainTags: [...]}
[EventStore] Loaded event CourseCreatedEvent  {eventId: "...", appliedAt: "...", metadata: {...}, domainTags: [...]}
[EventStore] Ended loading events            {domainTags: [...], duration: 0.0042}

Command handling:

[UseCase] Started handling CreateCourseCommand by CreateCourse  {domainTags: [...]}
[UseCase] Finished handling CreateCourseCommand by CreateCourse {domainTags: [...], duration: 0.0051}

Saga event handling:

[Saga] Started handling OrderPlacedEvent by OrderFulfillmentSaga  {sagaId: "order-123"}
[Saga] Finished handling OrderPlacedEvent by OrderFulfillmentSaga {sagaId: "order-123", duration: 0.0023}

On failure, the log includes exception (message) and exceptionClass in the context. All durations are measured in seconds using microtime(true).

Symfony bundle configuration¶

When using the Symfony bundle, logging decorators are enabled by default. They automatically wrap the core components using Symfony's service decoration. No additional configuration is needed.

The logger service can be customized in gember_event_sourcing.yaml:

gember_event_sourcing:
    logging:
        logger: '@logger'  # default