Add env vars to use raw body and set max json size

Description

This change adds the use of 2 environment variables: RAW_BODY and MAX_JSON_SIZE, allowing users to receive the request body as a buffer (the 'raw' body) as well as the ability to set the maximum JSON body size. The raw body is required when processing Stripe webhooks The max JSON body size is defaulted to a low limit from body-parser which has caused issues with users in the past.

Signed-off-by: Burton Rheutan rheutan7@gmail.com

Motivation and Context

[X] I have raised an issue to propose this change (required)

There was some discussion in the issue linked below. I've decided to implement the change in this was so that it was a more overall change rather than adding it to a specific verb (POST) to avoid surprising results when a user sets the RAW_BODY to true, it won't be limited only to post requests.

This also means that PUT, DELETE, and GET requests will also use the raw parser, but I think that would be understood when a user creates a function and explicitly sets the RAW_BODY variable to true expecting that the raw request body will be used.

Which issue(s) this PR fixes

Fixes #191

How Has This Been Tested?

Created sample function to print request body for verifying the type received by the function code.

Using Postman, called the function with application/json request.

No changes - { some: 'thing' }
env var RAW_BODY: true - <Buffer 7b 0a 09 22 73 6f 6d 65 22 3a 20 22 74 68 69 6e 67 22 0a 7d>

For the MAX_JSON_SIZE testing: I've used an example request from HugeJsonViewer example that is 1.5mb

Using Postman, called the function with a large request body:

node-raw.1.nil4m16x2t2q@pop-os    | 2020/02/01 20:45:49 stderr: PayloadTooLargeError: request entity too large
node-raw.1.nil4m16x2t2q@pop-os    | 2020/02/01 20:45:49 stderr:     at IncomingMessage.onData (/home/app/node_modules/raw-body/index.js:246:12)
node-raw.1.nil4m16x2t2q@pop-os    | 2020/02/01 20:45:49 stderr:     at IncomingMessage.emit (events.js:210:5)
node-raw.1.nil4m16x2t2q@pop-os    | 2020/02/01 20:45:49 stderr:     at addChunk (_stream_readable.js:308:12)
node-raw.1.nil4m16x2t2q@pop-os    | 2020/02/01 20:45:49 stderr:     at readableAddChunk (_stream_readable.js:289:11)
node-raw.1.nil4m16x2t2q@pop-os    | 2020/02/01 20:45:49 stderr:     at IncomingMessage.Readable.push (_stream_readable.js:223:10)
node-raw.1.nil4m16x2t2q@pop-os    | 2020/02/01 20:45:49 stderr:     at HTTPParser.parserOnBody (_http_common.js:128:22)
node-raw.1.nil4m16x2t2q@pop-os    | 2020/02/01 20:45:49 POST / - 413 Payload Too Large - ContentLength: 597

Adding the following to the fn1.yml:

    environment:
      MAX_JSON_SIZE: '5mb'

The result was successful:

node-raw.1.dzsb7o50ahso@pop-os    | 2020/02/01 20:49:45 stdout:   ... 237 more items
node-raw.1.dzsb7o50ahso@pop-os    | 2020/02/01 20:49:45 stdout: ]
node-raw.1.dzsb7o50ahso@pop-os    | 2020/02/01 20:49:45 POST / - 200 OK - ContentLength: 5424

Types of changes

[X] Bug fix (non-breaking change which fixes an issue)
[X] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
[ ] Version change (see: Impact to existing users)

Impact to existing users

None as the changes are wrapped in an environment variable. Verified the function works as expected without the env vars defined or used.

Checklist:

[X] My code follows the code style of this project.
[X] My change requires a change to the documentation.
[X] I have updated the documentation accordingly.
[X] I've read the CONTRIBUTION guide
[X] I have signed-off my commits with git commit -s
[ ] I have added tests to cover my changes.
[X] All new and existing tests passed.

openfaas / templates