Today in this blog we will be learning how to add monitoring support to our Go application. Before starting we will learn more about Prometheus.

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What is Prometheus ?

Prometheus is an open-source system monitoring and alerting tool. Prometheus collects and stores its metrics as time-series data, i.e. metrics information is stored with the timestamp at which it was recorded, alongside optional key-value pairs called labels. Now we have some idea about what Prometheus is !! Let's start the implementation.

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1. Installing Prometheus libraries.

Run the below commands to install Prometheus libraries.

go get github.com/prometheus/client_golang/prometheus
go get github.com/prometheus/client_golang/prometheus/promauto
go get github.com/prometheus/client_golang/prometheus/promhttp

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2. Writing the Go application.

We will implement Prometheus libraries in our Go code. To expose Prometheus metrics, We need to provide a /metrics HTTP endpoint. We will use promhttp as the handler function. This will expose the metrics at,

localhost:8080/metrics

We have added a custom metric called "my_custom_metric" which will increment its value after every 5 seconds.

package main

import (
        "net/http"
        "time"

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

func recordCustomMetrics() {
        go func() {
                for {
                        mymetric.Inc()
                        time.Sleep(5 * time.Second)
                }
        }()
}

var (
        mymetric = promauto.NewCounter(prometheus.CounterOpts{
                Name: "my_custom_metric",
                Help: "total number for my custom action",
        })
)

func main() {
        recordCustomMetrics()
        http.Handle("/metrics", promhttp.Handler())
        http.ListenAndServe(":8080", nil)
}

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3. Running the Application and verifying the metric.

Execute the below command to run the application.

go run main.go

After the application is started we can hit localhost:8080/metrics to check for metrics.

As we can see the metric is visible in the metrics section.

For more information on Prometheus visit, prometheus.io

Thanks for reading. Hope you have a great day 😁