How to pass a querystring or route parameter to AWS Lambda from Amazon API Gateway

As of September 2017, you no longer have to configure mappings to access the request body.

All you need to do is check, "Use Lambda Proxy integration", under Integration Request, under the resource.

You'll then be able to access query parameters, path parameters and headers like so

event['pathParameters']['param1']
event["queryStringParameters"]['queryparam1']
event['requestContext']['identity']['userAgent']
event['requestContext']['identity']['sourceIP']

The steps to get this working are:

Within the API Gateway Console ...

1. go to Resources -> Integration Request
2. click on the plus or edit icon next to templates dropdown (odd I know since the template field is already open and the button here looks greyed out)
3. Explicitly type application/json in the content-type field even though it shows a default (if you don't do this it will not save and will not give you an error message)

4. put this in the input mapping { "name": "$input.params('name')" }

5. click on the check box next to the templates dropdown (I'm assuming this is what finally saves it)

I have used this mapping template to provide Body, Headers, Method, Path, and URL Query String Parameters to the Lambda event. I wrote a blog post explaining the template in more detail: http://kennbrodhagen.net/2015/12/06/how-to-create-a-request-object-for-your-lambda-event-from-api-gateway/

Here is the Mapping Template you can use:

{
  "method": "$context.httpMethod",
  "body" : $input.json('$'),
  "headers": {
    #foreach($param in $input.params().header.keySet())
    "$param": "$util.escapeJavaScript($input.params().header.get($param))" #if($foreach.hasNext),#end

    #end
  },
  "queryParams": {
    #foreach($param in $input.params().querystring.keySet())
    "$param": "$util.escapeJavaScript($input.params().querystring.get($param))" #if($foreach.hasNext),#end

    #end
  },
  "pathParams": {
    #foreach($param in $input.params().path.keySet())
    "$param": "$util.escapeJavaScript($input.params().path.get($param))" #if($foreach.hasNext),#end

    #end
  }  
}