FaaS（Functions as a Service）函数即服务，FaaS是无服务器计算的一种形式，当前使用最广泛的是AWS的Lambada。
现在当大家讨论Serverless的时候首先想到的就是FaaS，有点甚嚣尘上了。FaaS本质上是一种事件驱动的由消息触发的服务，FaaS供应商一般会集成各种同步和异步的事件源，通过订阅这些事件源，可以突发或者定期的触发函数运行。
当前开源的FaaS框架大部分都是基于Kuberentes来实现的，例如：
- faas-netes - Enable Kubernetes as a backend for Functions as a Service (OpenFaaS) https://github.com/alexellis/faas
- fn - The container native, cloud agnostic serverless platform. http://fnproject.io
- funktion - a CLI tool for working with funktion https://funktion.fabric8.io/
- fx - Poor man's serverless framework based on Docker, Function as a Service with painless.
- IronFunctions - IronFunctions - the serverless microservices platform. http://iron.io
- kubeless - Kubernetes Native Serverless Framework http://kubeless.io
- nuclio - High-Performance Serverless event and data processing platform
- OpenFaaS - OpenFaaS - Serverless Functions Made Simple for Docker & Kubernetes https://blog.alexellis.io/introducing-functions-as-a-service/
- OpenWhisk - Apache OpenWhisk (Incubating) is a serverless, open source cloud platform that executes functions in response to events at any scale.
- Knative - Kubernetes-based platform to deploy and manage modern serverless workloads.
关于整个Cloud Native开源生态，请参考awesome-cloud-native。