echo_proxy

A server that forwards requests from Amazon's Alexa API to a configurable location

You might also consider checking out alexa_dispatcher, which allows you to forward requests for different Alexa skills to different endpoints.

About

echo_proxy is a simple servlet that receives requests from Amazon's Alexa API and forwards them to a configurable location. There are two reasons you might want this:

The language you're writing your skill in doesn't yet have support.
Secure gateway for home networks. If you're hosting your app on a home network, you'll need to make a home server accessible to the web. You probably don't want to expose any part of your app other than what's necessary for Amazon to call your service. echo_proxy provides that:
All requests it forwards are from Amazon. This is ensured by verifying cryptographic signatures included with each request.
echo_proxy is the only thing you'll need to expose to the outside world for your app to function. The guts of your app can remain internal to your network.

Running

Check out this project:

$ git clone git@github.com:sidoh/echo_proxy.git ./echo_proxy

Edit the configuration:

Edit ./echo_proxy/config/config.yml to suit your needs. In particular, make sure that you update the endpoint property to be the desired forward address.

Run it!

You should be able to start the server with the provided run.sh script:

$ ./echo_proxy/bin/run.sh

This is just a wrapper around a mvn command.

Run it! (As a daemon)

You can also use ./echo_proxy/bin/start to run echo_proxy as a daemon. Output will be redirected to ./echo_proxy/log/echo_proxy.out. You can use ./echo_proxy/bin/stop to stop the daemon.

Integrating

The server sends a POST request to the provided URL. The request information sent by Amazon is stuffed into a single object, and put in the body of the POST request. Here's a sample request:

{
  "requestType": "IntentRequest",
  "request": {
    "intent": {
      "name": "NextBus",
      "slots": {
        "Route": {
          "name": "Route",
          "value": "thirty eight"
        }
      }
    },
    "requestId": "amzn1.echo-api.request.157f3045-9c73-41af-982d-2a25d1b7208c",
    "timestamp": "Aug 4, 2015 10:53:12 PM"
  },
  "session": {
    "isNew": true,
    "sessionId": "<session id>",
    "application": {
      "applicationId": "<app id>"
    },
    "attributes": {
    },
    "user": {
      "userId": "<user id>"
    }
  }
}

SSL

This servlet doesn't handle SSL. Setting up SSL with jetty is really annoying, and I much prefer to do it with nginx. My nginx config looks like this:

server {
  listen 443 ssl;

  ssl_certificate /etc/nginx/ssl/echo-proxy.sidoh.org/nginx.crt;
  ssl_certificate_key /etc/nginx/ssl/echo-proxy.sidoh.org/nginx.key;

  location /{
    proxy_pass  http://127.0.0.1:8888;
  }
}