Google App Engine compatibility

[pjebs]

Introduction

Google App Engine is a sandboxed environment. We can't make calls to the outside world without using the net/http's Request to create a http.Client by:

import (
        "net/http"

        "google.golang.org/appengine"
        "google.golang.org/appengine/urlfetch"
)
ctx := appengine.NewContext(r)
client := urlfetch.Client(ctx)

Without doing that, the library doesn't work.

The way Stripe-Go-Library handles it is like this: https://github.com/stripe/stripe-go#google-appengine

Basically Stripe allows Google App Engine users the ability to feed in their own http Client and the library will then use that.

    ctx := appengine.NewContext(r)
    httpClient := urlfetch.Client(ctx)

    sc := client.New(key, stripe.NewBackends(httpClient))

The way I handle it is like this:

https://github.com/pjebs/optimus-go/blob/master/gae.go
https://github.com/pjebs/optimus-go/blob/master/standalone.go

My way may be a lot easier to implement.

In your code, everytime you refer to a http Client, you instead call: client() from the files above.

There will be no affect to the rest of your code.

More information

https://cloud.google.com/appengine/docs/go/issue-requests
https://cloud.google.com/appengine/docs/go/urlfetch/reference

[pjebs]

Since you are using gorequest library @L102:

You can see that gorequest exposes the Client.

You can use the approach I used above so that for non-GAE, the function above literally re-returns the net/http Client reference.

For the GAE version, it can grab the Jar https://github.com/parnurzeal/gorequest/blob/develop/gorequest.go#L97,
create the GAE urlfetch.Client(ctx) and then replace it.

[mltucker]

I think it's not as simple since the client this library creates has the jsonKey baked in.

This seems to be how to get it running on GAE:

func New(ctx context.Context, jsonKey []byte) (Client, error) {
	conf, err := google.JWTConfigFromJSON(jsonKey, androidpublisher.AndroidpublisherScope)

	if err != nil {
		return Client{}, err
	}

	httpClient := &http.Client{
		Transport: &oauth2.Transport{
			Source: conf.TokenSource(ctx),
			Base: &urlfetch.Transport{
				Context: ctx,
			},
		},
	}

	return Client{
		httpClient: httpClient,
	}, err
}

[mltucker]

I'm doing app store verification manually. But to get play store verification working, I copied the playstore/validator.go to my project and edited it. Gist here:

https://gist.github.com/mltucker/db4df00918d7b917f49b60012b615c02