How to use wildcards in ExpressJs and Fastify monitoring libraries

Valerio Barbera

With the booming software economy, the demand for new applications and software-defined automations is set to grow in the future years.

Companies in any industry are creating software in the form of internal business tools, productivity tools, integrations, automations, and more. As a result, there is a need for tools that make it easy to create and maintain software over time.

The software delivery lifecycle can be optimized by automating many tasks developers perform manually, like application debugging, monitoring and control, alerts, and collecting customer feedback.

If you have an application that helps your company generate revenue, it’s very easy to get these benefits and help your development team to become more efficient and productive with Inspector.

See for yourself what other developers think:

What is Inspector

Inspector is a Code Execution Monitoring tool that helps developers identify bugs and bottlenecks in their applications automatically.

Depending on the programming language you use, you can connect your application using different libraries as you can see in our GitHub account:

In the Inspector dashboard you can analyze the data visually. Inspector will monitor your code execution in real time, alerting you if something goes wrong.

screenshot inspector errors and exceptions details

In some cases, not all application parts need to be monitored. Maybe because you want to restrict the focus of your development activity, or to mitigate data consumption excluding requests for not-interesting assets, just as an example.

Following recent updates if you are integrating Inspector into your app you can now configure “Exclude Paths” using wildcards.

Connecting your Application to Inspector

If you don’t have an account yet, you can create a new one here:

Step 1 – Create a new application

After logging in to your Inspector account dashboard, create a new project.

Step 2 – Install the library

Run the npm command below in your terminal:

npm install @inspector-apm/inspector-nodejs --save

Step 3 – Initialization

To monitor the code execution in real time you need to Initialize the Inspector module at the first line, before you require any other modules in your application – i.e. before express, http, mysql, etc.

Later you can use the expressMiddleware() in your express instance.

 * -------------------------------------------
 * Initialize Inspector with the Ingestion Key.
 * --------------------------------------------
const inspector = require('@inspector-apm/inspector-nodejs')({
  ingestionKey: 'xxxxxxxxxxxxx',
const app = require('express')();
 * -----------------------------------------------
 * Attach the middleware to monitor HTTP requests.
 * ------------------------------------------------

 * ---------------------------------
 * Other application routes.
 * ---------------------------------
app.get('/', function (req, res) {
    return res.send('Home Page!');

Exclude Paths

If you want to turn off monitoring in some parts of your application you can pass a JSON object to the expressMiddleware function with excludePaths property to define which routes you want to exclude:

    excludePaths: [

You can also use the wildcard character * to match a subset of your urls:

    excludePaths: [
        // Single wildcard
        // Multiple wildcards

Why would you use a wildcard?

There could be parts of your application that don’t affect the user experience. Think about a backend admin panel. You would exclude this private part of your system and focus your monitoring data on what your customers use.

Our implementation of wildcard match function

Unfortunately, the framework does not support wildcards by default to identify the path of the current request.

Below you can find our implementation included in the ExpressJs and Fastify plugin:

exports.wildcardMatchRule = function(str, rule) {
    let escapeRegex = (str) => str.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1");
    return new RegExp("^" + rule.split("*").map(escapeRegex).join(".*") + "$").test(str);

Check out the code in our GitHub repository:

We use the wildcard match function in the express middleware that iterates the list of excluded paths passed during initialization checking for a match with the path of the current request. 

If it found a match the middleware doesn’t start a transaction:

The same is in the fastify plugin:

Try Inspector for free now

If you are interested in automating all manual monitoring habits we offer a complete free tier to help you make your experiments without pressure.

Inspector works with a simple software library. It doesn’t require any difficult installation on the underlying infrastructure, so it is perfect for software development teams.

Navigate to our website for more information or drop in a live chat if you need help. We are happy to support you and your team to avoid losing customers and money due to unexpected technical errors in your application.

Related Posts

How to make Vite Hot Module Replacement work on Windows

As many of our community members already know, we recently started the renovation of the Inspector dashboard UI with a fresh new design and a modern technology stack. In this article I will explain why we decided to leave Webpack and embrace Vite as assets build tool and Hot Module Replacement. I will show you

Http traffic monitoring for Slim framework

This article follows the release of the first version of the monitoring library for Slim framework. Thanks to this package you can fully monitor the HTTP traffic against your application based on Slim. It takes less than one minute to get started. First let me give you a bit of context. Introducing the Slim framework

Laravel Vapor application observability with Inspector

Recently, more and more Inspector customers are writing to me for advice on how to integrate our observability platform to monitor their Laravel application deployed in the AWS serverless environment with Vapor. So I decided to write an extended tutorial for the different options you have to use Inspector to monitor your serverless Laravel application.

How to build scalable applications

Get the e-book about the Inspector scalability journey.