Metrics Module

Overview

Yokai provides a fxmetrics module, allowing your application to provide metrics.

It wraps the Prometheus module.

Installation

The fxmetrics module is automatically loaded by Yokai's core.

When you use a Yokai application template, you have nothing to install, it's ready to use.

Configuration

configs/config.yaml

modules:
  metrics:
    collect:
      build: true    # to collect build infos metrics (disabled by default)
      go: true       # to collect go metrics (disabled by default)
      process: true  # to collect process metrics (disabled by default)

Usage

This module will enable Yokai to collect registered metrics collectors, and make them available to a metrics registry in its dependency injection system.

Metrics creation

You can add metrics anywhere in your application.

For example:

internal/service/example.go

package service

import (
    "fmt"

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

var ExampleCounter = prometheus.NewCounter(prometheus.CounterOpts{
    Name: "example_total",
    Help: "Example counter",
})

type ExampleService struct {}

func NewExampleService() *ExampleService {
    return &ExampleService{}
}

func (s *ExampleService) DoSomething() {
    // service logic
    fmt.Println("do something")

    // increment counter
    ExampleCounter.Inc()
}

Metrics registration

Even if convenient, it's recommended to NOT use the promauto way of registering metrics, as it uses a global registry that leads to data race conditions (especially while testing).

You can instead register your metrics collector with the AsMetricsCollector() function:

internal/register.go

package internal

import (
    "github.com/ankorstore/yokai/fxmetrics"
    "github.com/foo/bar/internal/service"
    "go.uber.org/fx"
)

func Register() fx.Option {
    return fx.Options(
        // register the ExampleCounter metrics collector
        fxmetrics.AsMetricsCollector(service.ExampleCounter),
        // ...
    )
}

You can also register several metrics collectors at once with AsMetricsCollectors().

Metrics execution

Yokai's core HTTP server will automatically:

• expose the configured metrics endpoints
• use the registry to expose the registered metrics collectors

Following previous example, after invoking the ExampleService, the metrics endpoint will return:

[GET] /metrics

# ...
# HELP example_total Example counter
# TYPE example_total counter
example_total 1

You can also get, real time, the status of your metrics on the core dashboard: