Monitoring

if you are using Prometheus for monitoring you can copy this code to you project:

package metrics

import (
	"context"
	"fmt"

	"github.com/mrsoftware/circuitbreaker"
	"github.com/prometheus/client_golang/prometheus"
)

var _ prometheus.Collector = &CircuitCollector{}

const (
	circuitBreakerSystem = "circuit_breaker"
)

// CircuitCollector is used to collect circuit breaker stat using prometheus.
type CircuitCollector struct {
	circuit circuitbreaker.Manager
	State   *prometheus.Desc
	Success *prometheus.Desc
	Failure *prometheus.Desc
}

// NewCircuitCollector create new CircuitCollector.
func NewCircuitCollector(service, name string, circuit circuitbreaker.Manager) *CircuitCollector {
	return &CircuitCollector{
		circuit: circuit,
		State: prometheus.NewDesc(
			prometheus.BuildFQName(
				service, circuitBreakerSystem, fmt.Sprintf("%s_state", name),
			),
			fmt.Sprintf("state of circuit breaker for %s service", name),
			nil, nil,
		),
		Failure: prometheus.NewDesc(
			prometheus.BuildFQName(
				service, circuitBreakerSystem, fmt.Sprintf("%s_failure_total", name),
			),
			fmt.Sprintf("failure count of circuit breaker for %s service", name),
			nil, nil,
		),
		Success: prometheus.NewDesc(
			prometheus.BuildFQName(
				service, circuitBreakerSystem, fmt.Sprintf("%s_success_total", name),
			),
			fmt.Sprintf("success count of circuit breaker for %s service", name),
			nil, nil,
		),
	}
}

// Describe give the collector descriptions about this collector metrics.
func (c *CircuitCollector) Describe(descs chan<- *prometheus.Desc) {
	// the Collect method will always return the same two metrics with the same two descriptors.
	prometheus.DescribeByCollect(c, descs)
}

// Collect implement prometheus collector Collect and used to give the collected metrics about ants.
func (c *CircuitCollector) Collect(metrics chan<- prometheus.Metric) {
	stat := c.circuit.Stat(context.Background())

	// collect current state.
	metrics <- prometheus.MustNewConstMetric(c.State, prometheus.GaugeValue, float64(stat.State))

	// collect failure count.
	metrics <- prometheus.MustNewConstMetric(c.Failure, prometheus.CounterValue, float64(stat.Failure))

	// collect success count.
	metrics <- prometheus.MustNewConstMetric(c.Success, prometheus.CounterValue, float64(stat.Success))
}

make sure the metric is registered using prometheus.Register function.