## Functions as a Service (OpenFaaS)

[![Go Report Card](https://goreportcard.com/badge/github.com/alexellis/faas)](https://goreportcard.com/report/github.com/alexellis/faas) [![Build
Status](https://travis-ci.org/alexellis/faas.svg?branch=master)](https://travis-ci.org/alexellis/faas) [![GoDoc](https://godoc.org/github.com/alexellis/faas?status.svg)](https://godoc.org/github.com/alexellis/faas)

![OpenFaaS](https://blog.alexellis.io/content/images/2017/08/faas_side.png)

OpenFaaS is a framework for building serverless functions with Docker which has first class support for metrics. Any process can be packaged as a function enabling you to consume a range of web events without repetitive boiler-plate coding.

**Highlights**

* Ease of use through UI portal and *one-click* install
* Write functions in any language for Linux or Windows and package in Docker/OCI image format
* Portable - runs on existing hardware or public/private cloud - [Kubernetes](https://github.com/alexellis/faas-netes) or Docker Swarm
* [CLI](http://github.com/alexellis/faas-cli) available with YAML format for templating and defining functions
* Auto-scales as demand increases

## Overview of OpenFaaS

![Stack](https://pbs.twimg.com/media/DFrkF4NXoAAJwN2.jpg)

### Function Watchdog

* You can make any Docker image into a serverless function by adding the *Function Watchdog* (a tiny Golang HTTP server)
* The *Function Watchdog* is the entrypoint allowing HTTP requests to be forwarded to the target process via STDIN. The response is sent back to the caller by writing to STDOUT from your application.

### API Gateway / UI Portal

* The API Gateway provides an external route into your functions and collects Cloud Native metrics through Prometheus.
* Your API Gateway will scale functions according to demand by altering the service replica count in the Docker Swarm or Kubernetes API.
* A UI is baked in allowing you to invoke functions in your browser and create new ones as needed.

> The API Gateway is a RESTful micro-service and you can view the [Swagger docs here](https://github.com/alexellis/faas/tree/master/api-docs).

### CLI

Any container or process in a Docker container can be a serverless function in FaaS. Using the [FaaS CLI](http://github.com/alexellis/faas-cli) you can deploy your functions or quickly create new functions from templates such as Node.js or Python.

> The CLI is effectively a RESTful client for the API Gateway.

**CLI walk-through**

Once you [have set up OpenFaaS](https://github.com/alexellis/faas#get-started-with-openfaas) you can follow these instructions:

Let's have a quick look at an example function `url-ping` which connects to a remote web server and returns the HTTP code from the response. It's written in Python.

```python
import requests

def handle(req):
        r =  requests.get(req, timeout = 1)
        print(req +" => " + str(r.status_code))
```
*handler.py*

```
$ curl -sSL https://cli.openfaas.com | sudo sh
```

*Install the faas-cli which is also available on `brew`*

Clone the samples and templates from Github:

```
$ git clone https://github.com/alexellis/faas-cli
$ cd faas-cli
```

Define your functions in YAML - or deploy via the API Gateway's UI.

```yaml
provider:
  name: faas
  gateway: http://localhost:8080

functions:
  url-ping:
    lang: python
    handler: ./sample/url-ping
    image: alexellis2/faas-urlping
```

*Example function YAML file - `url-ping.yaml`*

```
$ faas-cli -action build -f ./url-ping.yaml
```
*Build a Docker image using the Python handler in `./sample/url-ping`*

```
$ faas-cli -action deploy -f ./url-ping.yaml
```
*Deploy the new image to the gateway defined in the YAML file.*

> If your gateway is remote or part of a multi-host Swarm - you can also use the CLI to push your image to a remote registry or the Hub with `faas-cli -action push`

```
$ curl -d "https://cli.openfaas.com" http://localhost:8080/function/url-ping/
https://cli.openfaas.com => 200
```

*Test out the function with the URL https://cli.openfaas.com => 200*

[Sample functions](https://github.com/alexellis/faas/tree/master/sample-functions) are available in the Github repository in a range of programming languages.

## Get started with OpenFaaS

### Closing Keynote at Dockercon 2017

Functions as a Service or FaaS was a winner in the Cool Hacks contest for Dockercon 2017.

* [Watch my FaaS keynote at Dockercon 2017](https://blog.docker.com/2017/04/dockercon-2017-mobys-cool-hack-sessions/)

If you'd like to find the functions I used in the demos head over to the [faas-dockercon](https://github.com/alexellis/faas-dockercon/) repository.

**Background story**

This is my original blog post on FaaS from January: [Functions as a Service blog post](http://blog.alexellis.io/functions-as-a-service/)

### TestDrive

**Docker Playground**

You can quickly start OpenFaaS on Docker Swarm online using the community-run Docker playground: play-with-docker.com (PWD) by clicking the button below:

[![Try in PWD](https://cdn.rawgit.com/play-with-docker/stacks/cff22438/assets/images/button.png)](http://play-with-docker.com?stack=https://raw.githubusercontent.com/alexellis/faas/master/docker-compose.yml&stack_name=func)

**Docker Swarm**

A set of one-line scripts are provided to help you quickly test-drive OpenFaaS on Docker Swarm with a set of sample functions as defined in the provided [docker-compose.yml](https://github.com/alexellis/faas/blob/master/docker-compose.yml) file.

- `deploy_stack.sh` - for OSX/Linux on x86_64
- `deploy_stack.armhf.sh` - for Linux on ARM (Raspberry Pi for example)
- `deploy_stack.ps1` - for Windows

**Kubernetes**

Alternatively if you have a Kubernetes cluster you can [start here](https://github.com/alexellis/faas-netes).

### [Begin the TestDrive with Docker Swarm](https://github.com/alexellis/faas/blob/master/TestDrive.md)

Here is a screenshot of the API gateway portal - designed for ease of use.

![Portal](https://pbs.twimg.com/media/C7bkpZbWwAAnKsx.jpg)

### Community

Have you written a blog about OpenFaaS? Send a Pull Request to the community page below.

* [Read blogs/articles and find events about OpenFaaS](https://github.com/alexellis/faas/blob/master/community.md)

If you'd like to join OpenFaaS community Slack channel to chat with contributors or get some help - then send a Tweet to [@alexellisuk](https://twitter.com/alexellisuk/) or email alex@openfaas.com.

## Roadmap and contributing

OpenFaaS is written in Golang and is MIT licensed - contributions are welcomed whether that means providing feedback, testing existing and new feature or hacking on the source. To get started you can checkout the [roadmap and contribution guide](https://github.com/alexellis/faas/blob/master/ROADMAP.md) or [browse the open issues on Github](https://github.com/alexellis/faas/issues).

Highlights:

* New: Kubernetes support via [FaaS-netes](https://github.com/alexellis/faas-netes) plugin
* New: FaaS CLI and easy install via `curl` and `brew`
* New: Windows function support
* New: Asynchronous/long-running OpenFaaS functions via [NATS Streaming](https://nats.io/documentation/streaming/nats-streaming-intro/) - [Follow this guide](https://github.com/alexellis/faas/blob/master/guide/asynchronous.md)

Example of a Grafana dashboard linked to OpenFaaS showing auto-scaling live in action:

![](https://pbs.twimg.com/media/C9caE6CXUAAX_64.jpg:large)

Sample dashboard JSON file available [here](https://github.com/alexellis/faas/blob/master/contrib/grafana.json)