Integrate prometheus scraping endpoint with asp net core pipeline

Integrating Prometheus Scraping with ASP.NET Core Pipeline

ASP.NET Core is a powerful for building web applications and APIs. One common requirement in modern application is the ability to monitor and collect metrics. Prometheus is a popular open-source monitoring and alerting toolkit that provides a flexible and efficient solution for this purpose. In this article, we will explore how to integrate a Prometheus scraping endpoint with an ASP.NET Core pipeline.

Step 1: Installing the Prometheus .NET Client Library

The first step is to install the Prometheus .NET client library, which provides the necessary tools and utilities for exposing metrics in a format that Prometheus can scrape. You can install the library NuGet by running the following command in the Package Manager Console:

Install-Package prometheus-net.

Step 2: Configuring the Prometheus

Once the library is installed, you need to configure the Prometheus middleware in your ASP.NET Core pipeline. Open the Startup.cs file and add the following code to the ConfigureServices method:


This code registers the necessary services for the Prometheus middleware to work.

Next, add the following code to the Configure method:


This code adds the Prometheus middleware to the ASP.NET Core pipeline, enabling the scraping endpoint.

Step 3: Exposing Custom Metrics

By , the Prometheus middleware exposes a set of default metrics, such as HTTP request duration and error rate. However, you can also expose custom metrics specific to your application. Let's say you want to expose a metric for the number of active users. You can do this by adding the following code to your controller:

private readonly Counter _activeUsersCounter = Metrics.CreateCounter("active_users", "Number of active users");

public IActionResult GetActiveUsers()
    // Your code to retrieve active users

This code creates a counter metric named “active_users” and increments it every time the GetActiveUsers is called. You can then access this metric by scraping the Prometheus endpoint.

Step 4: Scraping Metrics with Prometheus

Now that you have configured the Prometheus middleware and exposed custom metrics, you can scrape the metrics using Prometheus. To do this, you need to configure Prometheus to scrape the ASP.NET Core application. Open the Prometheus configuration file (prometheus.yml) and add the following job configuration:

- job_name: 'my_aspnet_app'
  scrape_interval: 5s
    - targets: ['localhost:5000']

This configuration tells Prometheus to scrape the ASP.NET Core application running on localhost:5000 every 5 seconds. Adjust the target URL and scrape according to your application's configuration.


In this article, we have seen how to integrate a Prometheus scraping endpoint with an ASP.NET Core pipeline. By following steps, you can expose custom metrics and monitor the performance of your ASP.NET Core application using Prometheus. This integration provides valuable insights into the health and behavior of your application, enabling you to make informed decisions and optimize its performance.

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