Custom Exporters for Prometheus

Introduction Key Concepts Step-by-Step Guide Best Practices FAQ

1. Introduction

Prometheus is an open-source monitoring and alerting toolkit widely used in Cloud Native environments. To monitor custom systems or applications, developers can create custom exporters that expose metrics in a format compatible with Prometheus. This lesson covers how to create and implement custom exporters effectively.

2. Key Concepts

Exporter: A service that collects and exposes metrics for Prometheus to scrape.
Metrics: Data points that provide insights into system performance (e.g., CPU usage, memory consumption).
Scraping: The process where Prometheus collects metrics from an exporter at specified intervals.

3. Step-by-Step Guide to Creating a Custom Exporter

3.1. Set Up Your Environment

Install Go: The most common language for writing Prometheus exporters.
Set up your project directory:

mkdir my_exporter
cd my_exporter
go mod init my_exporter

3.2. Write the Exporter Code

Here is a simple example of a custom exporter that exposes a single metric:

package main

import (
    "net/http"
    "github.com/prometheus/client_golang/prometheus"
    "github.com/prometheus/client_golang/prometheus/promhttp"
)

var (
    myMetric = prometheus.NewGaugeVec(
        prometheus.GaugeOpts{
            Name: "my_custom_metric",
            Help: "This is my custom metric",
        },
        []string{"label"},
    )
)

func init() {
    prometheus.MustRegister(myMetric)
}

func main() {
    myMetric.WithLabelValues("example").Set(1)

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

3.3. Run Your Exporter

To run your exporter, execute:

go run main.go

Access your metrics at http://localhost:8080/metrics.

4. Best Practices

Keep your metrics simple and consistent.
Document each metric's purpose and usage.
Use labels wisely to avoid cardinality issues.
Handle errors gracefully, providing meaningful messages.

5. FAQ

What is a Prometheus exporter?

A Prometheus exporter is a service that collects metrics from a monitored application and exposes them in a format that Prometheus can scrape.

Can I use languages other than Go for exporters?

Yes, you can use any language, but Go is the most common due to its native support from the Prometheus client libraries.

How do I test my custom exporter?

You can test your exporter by accessing the metrics endpoint through a web browser or using curl: curl http://localhost:8080/metrics.

6. Flowchart for Custom Exporter Development

graph TD;
        A[Start] --> B[Define Metrics];
        B --> C[Choose Language];
        C --> D[Write Exporter Code];
        D --> E[Test Exporter];
        E --> F[Deploy Exporter];
        F --> G[Configure Prometheus];
        G --> H[Monitor Metrics];
        H --> I[End];