Metrics

Metrics are collected using several Meter instances. There are two available meters:

eventuous.application for command services
eventuous.subscriptions for subscriptions
eventuous.persistence for event stores

Producers do not provide meters, but you can use traces to collect diagnostics for producers.

Application metrics

Application metrics are collected for command services. The metrics are collected for the duration and error count of command processing. The metrics are tagged by:

command-service: the service type
command-type: command type

Command handling duration is collected as a histogram with the name eventuous_service_duration with measure unit milliseconds. The number of errors that occurred when handling commands is collected as a counter with the name eventuous_service_errors_count.

Here’s an example of command service metrics exported in Prometheus format:

# TYPE eventuous_service_duration_milliseconds histogram
# UNIT eventuous_service_duration_milliseconds milliseconds
# HELP eventuous_service_duration_milliseconds Command execution duration, milliseconds
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="0"} 0 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="5"} 0 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="10"} 0 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="25"} 0 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="50"} 0 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="75"} 0 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="100"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="250"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="500"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="750"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="1000"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="2500"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="5000"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="7500"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="10000"} 1 1725881998415
eventuous_service_duration_milliseconds_bucket{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom",le="+Inf"} 1 1725881998415
eventuous_service_duration_milliseconds_sum{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom"} 86.583 1725881998415
eventuous_service_duration_milliseconds_count{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom"} 1 1725881998415
# TYPE eventuous_service_errors_count_total counter
# UNIT eventuous_service_errors_count_total errors
# HELP eventuous_service_errors_count_total Number of failed commands
eventuous_service_errors_count_total{otel_scope_name="eventuous.application",otel_scope_version="0.15.0.0",command_service="BookingsCommandService",command_type="BookRoom"} 1 1725881998415

Persistence metrics

When Eventuous diagnostics is enabled (by default), registering any persistence component like event reader, writer or store will wrap it in a diagnostic decorator. The decorator collects persistence metrics. The metrics are tagged by:

operation: the operation type (append, read, etc)
component: the persistence implementation type, for example EsdbEventStore

Persistence operation duration is collected as a histogram with the name eventuous_persistence_duration with measure unit milliseconds. The number of errors that occurred when executing persistence operations is collected as a counter with the name eventuous_persistence_errors_count.

Here’s an example of persistence metrics exported in Prometheus format:

# TYPE eventuous_persistence_duration_milliseconds histogram
# UNIT eventuous_persistence_duration_milliseconds milliseconds
# HELP eventuous_persistence_duration_milliseconds Event store operation duration, milliseconds
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="0"} 0 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="5"} 0 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="10"} 0 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="25"} 0 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="50"} 0 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="75"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="100"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="250"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="500"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="750"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="1000"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="2500"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="5000"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="7500"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="10000"} 1 1725888603727
eventuous_persistence_duration_milliseconds_bucket{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append",le="+Inf"} 1 1725888603727
eventuous_persistence_duration_milliseconds_sum{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append"} 66.672 1725888603727
eventuous_persistence_duration_milliseconds_count{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append"} 1 1725888603727
# TYPE eventuous_persistence_errors_count_total counter
# UNIT eventuous_persistence_errors_count_total errors
# HELP eventuous_persistence_errors_count_total Number of failed event store operations
eventuous_persistence_errors_count_total{otel_scope_name="eventuous.persistence",otel_scope_version="0.15.0.0",component="EsdbEventStore",operation="append"} 1 1725888603727

Subscription metrics

Subscription metrics are described in the subscriptions diagnostics page.