Updates for Rancher.

guide/backends.md

@@ -22,6 +22,29 @@ Here are some ideas:
 
 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](https://github.com/alexellis/faas/tree/master/api-docs) 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](https://github.com/alexellis/faas-netes):
+
+![](https://camo.githubusercontent.com/c250e0dc975e50b6fae3fc84ba5cdc0274bc305c/68747470733a2f2f7062732e7477696d672e636f6d2f6d656469612f44466837692d5a586b41415a6b77342e6a70673a6c61726765)
+
+### 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](https://github.com/alexellis/faas-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
@@ -48,9 +71,21 @@ Method(s): POST
 
 Method(s): POST
 
+
 ### Examples / documentation
 
+* See the [Swagger API](https://github.com/alexellis/faas/tree/master/api-docs) 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](https://github.com/alexellis/faas-netes/tree/master/handlers) for examples of how to implement each endpoint.
 
-* See the [Swagger API](https://github.com/alexellis/faas/tree/master/api-docs)
+#### Rancher / Cattle (community)
+
+This work is by Ken Fukuyama from Japan.
+
+* [Blog post](https://medium.com/@kenfdev/openfaas-on-rancher-684650cc078e)
 
+* [faas-rancher](https://github.com/kenfdev/faas-rancher) implementation in Golang