faas/guide/backends.md

OpenFaaS backends guide

OpenFaaS is a framework for building serverless functions with containers and running them at scale.

Bring Serverless OpenFaaS functions to your favourite container platform.

We support two orchestration platforms or "backends":

• Docker Swarm
• Kubernetes

There is also community work in-progress to support:

• Rancher/Cattle
• Nomad
• DCOS
• Hyper.sh

The Docker Swarm support is built-into the faas repo, but the Kubernetes support is provided by a microservice in the faas-netes repo.

If you're thinking of writing a new back-end we'd love to hear about it and help you, so please get in touch with alex@openfaas.com. Existing implementations (like OpenFaaS) are written in Golang and this provides a level of consistency across the projects.

I need a backend for X

This project is focusing on Docker Swarm and Kubernetes, but we're open to support from third parties and vendors for other backends:

Here are some ideas:

• Nomad
• Marathon Mesos
• AWS ECS
• Hyper.sh

If you would like to write your own back-end for X then you can write your own microservice that conforms to the Swagger API here.

How does my back-end work?

In order to support a new back end you will write a new "external_provider" and configure this on the API Gateway. The API Gateway will then proxy any requests to your new microservice. The first "external_provider" was the Kubernetes implementation faas-netes:

Deploy a function - through the built-in Swarm support or through faas-netes

Invoke your function - through the built-in Swarm or via faas-netes

Find out more about the watchdog here.

Automatically compatible OpenFaaS

The following are fully compatible with any additional back-ends:

• API Gateway
• Promethes metrics (tracked through API Gateway)
• The built-in UI portal (hosted on the API Gateway)
• The Function Watchdog and any existing OpenFaaS functions
• The CLI
• Asynchronous function invocation

Dependent on back-end:

• Secrets or environmental variable support
• Windows Containers function runtimes (i.e. via W2016 and Docker)
• Scaling - dependent on underlying API (available in Docker & Kubernetes)

Backend endpoints:

• List / Create / Delete a function

/system/functions

Method(s): GET / POST / DELETE

• Get a specific function

/system/function/{name:[-a-zA-Z_0-9]+}

Method(s): GET

• Scale a specific function:

/system/scale-function/{name:[-a-zA-Z_0-9]+}

Method(s): POST

• Invoke a specific function

/function/{name:[-a-zA-Z_0-9]+}

Method(s): POST

Examples / documentation

• See the Swagger API as a starting point.

faas-netes (Kubernetes)

The Kubernetes integration was written by Alex Ellis and is officially supported by the project.

• See the FaaS-netes handlers for examples of how to implement each endpoint.

Rancher / Cattle (community)

This work is by Ken Fukuyama from Japan.

• Blog post

• faas-rancher implementation in Golang