Metrics

Observability is crucial when operating a SaaS system because it’s not possible to debug it live. Alongside structured logging and distributed tracing, metrics are one of the pillars of observability.

Microbus supports both push and pull models:

• To push metrics to an OpenTelemetry collector, set the OTEL_EXPORTER_OTLP_METRICS_ENDPOINT or OTEL_EXPORTER_OTLP_ENDPOINT environment variable appropriately
• Alternatively, set the MICROBUS_PROMETHEUS_EXPORTER environment variable and configure Prometheus to scrape metrics from the metrics core microservice

When pushing over OTLP, all exporters in one executable that target the same collector share a single connection across the traces, metrics and logs signals. svc.MeterProvider() returns the underlying OpenTelemetry meter provider — a no-op provider (never nil) when metrics are disabled — so application code can instrument third-party libraries against the same metrics pipeline and resource as the framework.

Standard Metrics

By default, all microservices produce a standard set of metrics:

• The microservice’s uptime
• Histogram of the execution time of callbacks such as OnStartup, OnShutdown, tickers, etc.
• Histogram of the processing time of incoming requests
• Histogram of the size of the response to incoming requests
• Count of outgoing requests, along with the error and status code
• Histogram of time to receive an acknowledgement from a downstream microservice
• Count of log messages recorded
• Count of distributed cache operations, including hit and miss stats
• Memory usage of the distributed cache

Custom Metrics

Custom metrics are defined using the Connector’s DescribeCounter, DescribeGauge or DescribeHistogram. Metrics are incremented or observed using IncrementCounter, RecordGauge or RecordHistogram, depending on their type.

The coding agent can assist in the definition of metrics.

Hey Claude, create a metric that counts the number of likes per post ID.

IncrementCounterLikes (or something similar) will be created by the coding agent in intermediate.go.

func (svc *Intermediate) IncrementCounterLikes(ctx context.Context, num int, postId string) error {
	// ...
}

It can then be used to count the number of likes from anywhere in the microservice’s code.

func (svc *Service) Like(ctx context.Context, postId string) error {
	// ...

	err := svc.IncrementCounterLikes(ctx, 1, postId)
	if err != nil {
		return errors.Trace(err)
	}
	return nil
}

See Also

• Calculator example — pairs a counter (UsedOperators, incremented inline in every arithmetic call) with an observable gauge (SumOperations, populated by an OnObserveSumOperations JIT observer reading per-operator atomic.Int64 accumulators). The canonical “running total” pattern.