Faas: Feature: proxy HTTP redirect requests for synchronous requests

[alexellis]

Expected Behaviour

The API Gateway could proxy HTTP "redirect" requests for synchronous requests. These happen when a function returns a HTTP redirect status code plus a Location: scheme://url header.

The of-watchdog and stateless microservices can return custom / bespoke HTTP headers.

This does not apply or make any sense for asynchronous invocations.

Current Behaviour

This technically "works as designed" in that any Location/redirect request is followed by the Golang proxying code and therefore if a function asks to redirect to https://google.com -> the API gateway's proxy code will download that page and return it.

Possible Solution

I implemented this for the OpenFaaS Cloud Auth service, the same approach can be applied to the http.Client. https://github.com/openfaas/openfaas-cloud/blob/3d3ed09707817b436751b279973d6f26191930a4/router/main.go#L34

Steps to Reproduce (for bugs)

1. Use of-watchdog or a stateless microservice
2. Send a HTTP header of "Location:" and a HTTP status code to redirect
3. See that page returned but on the location / address of the function.

I.e. with node8-express:

"use strict"

module.exports = (event, context) => {
  context
    .headers({'Location': 'https://www.google.com/'})
    .status(307)    // Temporary
    .succeed('Page has moved.')
}

Context

Reported by a user who wanted to do OAuth redirects from a function. https://github.com/openfaas-incubator/of-watchdog/issues/34

The watchdog / of-watchdog may need an additional change, but the gateway can be proven out just with a container exposing port 8080. https://docs.openfaas.com/reference/workloads/

It goes without saying that this needs to be fully tested and with not just the "happy path" scenario.

[alexellis]

I've tried this with a stateless microservice adapted from the node8-express template, and the code patch above. It worked :+1:

Separate testing/changes may be needed for the watchdogs.

[alexellis]

Feature released via 0.9.7

[alexellis]

Derek close: released.

[pyramation]

Awesome!