Configuration

Configuration is loaded from the events: section of application.yaml and injected into EventsProvider via config_key = "events".

Env-Var Prefix

All keys can be overridden with environment variables using the prefix LEX_EVENTS__:

LEX_EVENTS__NAME=prod-events \
LEX_EVENTS__EVENT_STORE_BACKEND=postgres \
LEX_EVENTS__ENABLED=true

Top-Level: EventsConfig

Config section key: events

Key	Type	Default	Env Var	Description
name	str	"events"	LEX_EVENTS__NAME	Instance name
enabled	bool	True	LEX_EVENTS__ENABLED	Enable events system
event_store_backend	EventStoreBackend	"memory"	LEX_EVENTS__EVENT_STORE_BACKEND	Backend: memory, postgres, mongodb, sqlite
debug	bool	False	LEX_EVENTS__DEBUG	Enable debug mode
env	str | None	None	LEX_EVENTS__ENV	Runtime environment
postgres	PostgresEventStoreConfig | None	None	LEX_EVENTS__POSTGRES__*	Postgres store config
mongodb	MongoDBEventStoreConfig | None	None	LEX_EVENTS__MONGODB__*	MongoDB store config
memory	InMemoryEventStoreConfig	defaults	LEX_EVENTS__MEMORY__*	In-memory store config
sqlite	SqliteConfig | None	None	LEX_EVENTS__SQLITE__*	SQLite store config
snapshots	SnapshotConfig	defaults	LEX_EVENTS__SNAPSHOTS__*	Snapshot config
command_bus	CommandBusConfig	defaults	LEX_EVENTS__COMMAND_BUS__*	Command bus config
query_bus	QueryBusConfig	defaults	LEX_EVENTS__QUERY_BUS__*	Query bus config
event_bus	EventBusConfig	defaults	LEX_EVENTS__EVENT_BUS__*	Event bus config
saga	SagaConfig	defaults	LEX_EVENTS__SAGA__*	Saga config
projection	ProjectionConfig	defaults	LEX_EVENTS__PROJECTION__*	Projection config
streaming	StreamingConfig	defaults	LEX_EVENTS__STREAMING__*	Streaming config
logging_middleware	LoggingMiddlewareConfig	defaults	LEX_EVENTS__LOGGING_MIDDLEWARE__*	Logging middleware
validation_middleware	ValidationMiddlewareConfig	defaults	LEX_EVENTS__VALIDATION_MIDDLEWARE__*	Validation middleware
transaction_middleware	TransactionMiddlewareConfig	defaults	LEX_EVENTS__TRANSACTION_MIDDLEWARE__*	Transaction middleware
retry_middleware	RetryMiddlewareConfig	defaults	LEX_EVENTS__RETRY_MIDDLEWARE__*	Retry middleware
metrics_middleware	MetricsMiddlewareConfig	defaults	LEX_EVENTS__METRICS_MIDDLEWARE__*	Metrics middleware
rabbitmq	RabbitMQConfig | None	None	LEX_EVENTS__RABBITMQ__*	RabbitMQ adapter config
kafka	KafkaConfig | None	None	LEX_EVENTS__KAFKA__*	Kafka adapter config

CommandBusConfig

Key	Type	Default	Description
max_retries	int	3	Max command retry attempts
retry_delay_seconds	float	1.0	Delay between retries
timeout_seconds	float	30.0	Command execution timeout
enable_validation	bool	True	Enable command validation
enable_logging	bool	True	Enable command logging
enable_metrics	bool	True	Enable command metrics

EventBusConfig

Key	Type	Default	Description
max_concurrent_handlers	int	10	Max concurrent event handlers
handler_timeout_seconds	float	30.0	Per-handler timeout
retry_failed_handlers	bool	True	Retry on handler failure
max_handler_retries	int	3	Max retries per handler
enable_dead_letter	bool	True	Enable dead-letter queue
allow_no_handlers	bool	True	Allow events with no handlers
parallel_dispatch	bool	True	Dispatch to handlers in parallel
continue_on_error	bool	True	Continue on handler error
max_queue_per_subscriber	int	1000	Max queued events per subscriber

SnapshotConfig

Key	Type	Default	Description
enabled	bool	True	Enable aggregate snapshots
strategy	SnapshotStrategy	"event_count"	Strategy: event_count, time_based, on_demand
event_count_threshold	int	100	Events between snapshots
time_threshold_seconds	int	3600	Seconds between time-based snapshots
max_snapshots_per_aggregate	int	5	Max stored snapshots

Minimal YAML Example

events:
  event_store_backend: memory
  command_bus:
    max_retries: 3
    timeout_seconds: 30
  event_bus:
    parallel_dispatch: true
    continue_on_error: true

Production YAML Example (PostgreSQL)

events:
  event_store_backend: postgres
  postgres:
    dsn: "postgresql://user:pass@localhost:5432/events"
    schema: "events"
  snapshots:
    enabled: true
    strategy: event_count
    event_count_threshold: 50
  command_bus:
    max_retries: 3
    timeout_seconds: 60
  event_bus:
    parallel_dispatch: true
    continue_on_error: false
    enable_dead_letter: true

Env-Var Form

LEX_EVENTS__EVENT_STORE_BACKEND=postgres \
LEX_EVENTS__POSTGRES__DSN=postgresql://user:pass@localhost:5432/events \
LEX_EVENTS__SNAPSHOTS__ENABLED=true \
LEX_EVENTS__SNAPSHOTS__EVENT_COUNT_THRESHOLD=50 \
LEX_EVENTS__COMMAND_BUS__MAX_RETRIES=3 \
LEX_EVENTS__COMMAND_BUS__TIMEOUT_SECONDS=60 \
LEX_EVENTS__EVENT_BUS__PARALLEL_DISPATCH=true \
LEX_EVENTS__EVENT_BUS__CONTINUE_ON_ERROR=false \
LEX_EVENTS__EVENT_BUS__ENABLE_DEAD_LETTER=true