Lighthouse goes Serverless: Using OpenFaaS for Running Functions

7 min readJul 20, 2020

Lighthouse is a service to scan webpages and see how good they score on terms of SEO, performance and best practices. You can use the scanner here:

Currently lighthouse consists of three microservices: A frontend that delivers static HTML, an API to request new scans and query job status, and several workers that perform the actual web page scan. During refactoring the application into true microservices, I recognized that scaling the app is about scaling the workers. And as for now, I just provide a fixed number of workers, and each can only process up to 3 scans at the same time.

In this article, I explore and implement the concept of a serverless function. In a nutshell, serverless means that you implement and deploy a function with a standardized HTTP interface somewhere in the cloud, and the framework takes care of availability and scaling of this particular function. There are many serverless platform or providers available. The platform of my choice is OpenFaas. I will use OpenFaaS because it runs natively on Kubernetes, can be deployed easily, does not restrict the used programming language and uses (customizable) Docker images for function execution.

In this article, I will start with a short introduction to OpenFaaS. I will only cover core concepts, read my OpenFaas Deep Dive to get even more familiar. Then I will explain how the current worker node in my lighthouse functions. And then we will modify this microservice step-by-step to a serverless function.

This article originally appeared at my blog.

OpenFaaS Core Concepts

OpenFaaS provides a powerful command line utility to build, push, and deploy serverless applications. Users start by choosing a template for their functions. Templates consist of a special Docker image with a built-in health check functions as well as programming language specific software packages. When you choose a template, you can either get a base image, for example the NodeJS template, or a specialized template for an HTTP framework in this language, for example Express. The difference: The base image will just expose one function, and will just return HTTP status codes 200 and 400. The specialized…


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