I am referring to Amazon documentation for the purpose of Customer Authentication. Currently, I am using LWA.
Steps I followed:
I enabled the Send Alexa Events Permission from the Alexa developer Console in Build > Permission page.
I took the grant code from the request in the cloudwatch logs which was sent when I logged in using Alexa companion app.
Example:-
{
"directive": {
"header": {
"messageId": "Example",
"name": "AcceptGrant",
"namespace": "Alexa.Authorization",
"payloadVersion": "3"
},
"payload": {
"grant": {
"code": "Example2",
"type": "OAuth2.AuthorizationCode"
},
"grantee": {
"token": "Example3",
"type": "BearerToken"
}
}
}
}
Example:-
POST /auth/o2/token HTTP/l.l
Host: api.amazon.com
Content-Type: application/x-www-form-urlencoded;charset=UTF-8
grant_type=authorization_code&code=&client_id=&client_secret=
I passed the code,client_id, and client_secret in the above example and made the post request to this URL https://api.amazon.com/auth/o2/token
I followed the step given in the above documentation and I am stuck on the error ( 401 Unauthorized ):
{
"error_description": "The request has an invalid grant parameter : code",
"error": "invalid_grant"
}
I tried implementing it using Python code and Postman both. Ending up with the Same above error scenario.
Here is a sample code to help you and others who are looking to send events to alexa gateway.
const AWS = require('aws-sdk');
AWS.config.update({region: 'eu-west-1'});
// Create the DynamoDB service object
const ddb = new AWS.DynamoDB({ apiVersion: 'latest' });
const doc = new AWS.DynamoDB.DocumentClient({
convertEmptyValues: true,
service: ddb
});
// Using 'request' for http POST and GET request.
// https://www.npmjs.com/package/requests
// npm install --save requests
const r = require('request');
//Handle Authorization. Call this method from your lambda handler whenever you get Alexa.Authorization message. You will get this message only when you select permission to
//send events in your Smart Home Skill.
//Access to Event gateway allows you to enable Proactive Device Discovery and
//Proactive State Reporting in your skill
//More information on Alexa.Authorization can be found on https://developer.amazon.com/docs/device-apis/alexa-authorization.html
function handleAuthorization(request, context, user) {
//Even when you are using your own authentication, the url below will still
//point to amazon OAuth token url. The token you obtain here has to be stored
//separately for this user. Whenever sending an event to alexa event gateway you will
//require this token.
//URL below is for EU server. Look at following documentation link to identify correct url
//for your system.
//https://developer.amazon.com/docs/smarthome/send-events-to-the-alexa-event-gateway.html
var url = "https://api.amazon.com/auth/o2/token";
var body = {
grant_type : 'authorization_code',
code : request.directive.payload.grant.code,
client_id : 'your client id from permissions page on developer portal where you enable alexa events. This is id different than one you specify in account linking settings',
client_secret : 'client secret from permissions page'
}
//https://developer.amazon.com/docs/smarthome/authenticate-a-customer-permissions.html
r.post({
url: url,
form : body
}, function(error, response, b){
if (error) { return console.log(error); }
var body = JSON.parse(b);
var params = {
TableName: 'Devices',
Item: {
'id' : user,
'auth_token' : body.access_token,
'refresh_token' : body.refresh_token
}
}
log("DEBUG:", "Authorization Body", JSON.stringify(body));
log("DEBUG:", "Authorization Response", JSON.stringify(response));
log("DEBUG:", "Database Params", JSON.stringify(params));
// Call DynamoDB to add the item to the table
var putObjectPromise = doc.put(params).promise();
//Store auth_token and refresh_token in database. We will need these
//while sending events to event gateway.
//Send a success response.
putObjectPromise.then(function(data) {
var response = {
event: {
header: {
messageId: request.directive.header.messageId,
namespace: "Alexa.Authorization",
name: "AcceptGrant.Response",
payloadVersion: "3"
},
"payload": {
}
}
};
context.succeed(response);
}).catch(function(err) {
//TODO - Add a Authorization error response JSON here.
console.log(err);
});
});
}