What is OpenFaaS and what does it do?

Updated

OpenFaaS is a platform for running serverless functions on Kubernetes. It lets you package code as portable OCI images, deploy it to any Kubernetes cluster, and have it scale automatically — including down to zero when idle. It supports any programming language and can also host existing microservices alongside functions. There is an open-source edition and a commercial edition, OpenFaaS Pro, which adds autoscaling, event connectors, monitoring dashboards, SSO, RBAC, and direct engineering support.

The core idea

OpenFaaS turns code into functions that run as containers on Kubernetes. You write a function in whatever language you prefer, build it into an OCI image, and deploy it. The platform handles the rest: routing, scaling, and lifecycle.

The tagline on the site is "Serverless Functions, Made Simple," with the positioning "Serverless on your terms — stable, portable, built for production."

What it does

Anywhere

Functions deploy on-premises or in the cloud using portable OCI images. The same unified experience applies to any Kubernetes cluster, so you are not locked into a single provider.

Any code

You can write functions in any language, and bring existing microservices along too. This matters if you have services that are not functions but still need to run in the same environment.

Any scale

Pro features scale functions to meet demand and down to zero when idle. Scaling to zero is the cost-saving mechanism: when there is no traffic, there are no running instances.

Key capabilities

Capability What it means
Templates Get code into production within minutes using provided templates, or create your own
Efficient scaling Fine-tune scaling to match the type of traffic, including scaling to zero
Event-driven workloads Invoke functions through events from Apache Kafka, AWS SQS/SNS, GCP Pub/Sub, RabbitMQ, PostgreSQL, Cron, and MQTT

How teams use it

The site describes three common patterns:

A sandbox for customer code. If you want customers to extend your product with custom code, OpenFaaS turns code snippets into isolated functions built and deployed through a REST API. Each tenant runs in its own namespace with security boundaries enforced at every layer. The site cites Waylay (IoT), LivePerson, Cognite (ML/data-science), and RudderStack as production users.

ETL and data pipelines. For large volumes of data, OpenFaaS fans out to thousands of parallel function executions that scale automatically. Batch jobs and ML models run as functions with built-in retries, whether they take milliseconds or hours. Surge is cited as running async jobs at scale for background checks.

Kubernetes, made usable. Kubernetes has the building blocks, but wiring up auto-scaling, queuing, retries, and event triggers from scratch takes months. OpenFaaS packages these so you do not build them yourself.

Open source vs. OpenFaaS Pro

The open-source edition gives you the core function platform. OpenFaaS Pro adds autoscaling, event connectors, monitoring dashboards, SSO, RBAC, and direct-to-engineering support. The site links to a pricing page and a free trial request, so commercial terms are available there rather than stated on the homepage.

When to look further

OpenFaaS is worth investigating if you already run Kubernetes and want to add function deployment without building the scaling, queuing, and event-triggering layer yourself. It is also a fit if you need to run untrusted or customer-supplied code in isolation, or if you want event-driven workloads triggered by Kafka, SQS/SNS, Pub/Sub, RabbitMQ, PostgreSQL, Cron, or MQTT.

If you are not on Kubernetes, or you need a fully managed serverless platform with no cluster to operate, this is a different category of tool.