Expose raw body

[petermoon]

I'm building a webhook for GitHub, and I want to validate the signature. The signature involves hashing of the raw body, which isn't available inside the Lambda function.

[jamesls]

Looks like this is now possible via: https://aws.amazon.com/blogs/compute/amazon-api-gateway-mapping-improvements/

I'd need to configure the routes such that API gateway will base64 encode the body before handing it off to us. Then provide helper functions that allow you to access the raw body and automatically base64 decode the data for you.

[jamesls]

Implemented in #18. There's now app.current_request.raw_body.

I'll update the docs and also add sample apps shortly, but here's an example that works:

import hmac
import hashlib

from chalice import Chalice


app = Chalice(app_name='app1')

# Clearly, don't hardcode your secret key in your source.
KEY = 'mysupersecret'


@app.route('/postreceive', methods=['POST'])
def postme():
    h = hmac.new(KEY, app.current_request.raw_body, hashlib.sha1)
    actual = 'sha1=%s' % h.hexdigest()
    expected = app.current_request.headers.get('X-Hub-Signature', '<not specified>')
    print "Actual:", actual
    print "Expected:", expected
    if hmac.compare_digest(actual, expected):
        return {"success": "yes"}
    else:
        return {"success": "no"}