I'm currently moving my e-commerce app to Google App Engine. I'm using the PHP Flexible runtime (PHP flex).
One of the transaction requires a call upon my Payment Provider's HTTP API. The problem now, my Payment Provider requires all caller IP address to be white-listed beforehand through some out-of-band registration. Registration is very restricted, only accepting a handful of IPv4 address per client.
I know GAE will spawn new instance as needed which will be assigned IP address from a large pool. So registering a list of address is not an option either.
I know this defeats the purpose of automatic scaling but is there any way I can assign static IP address to my app?
Is there any other way to approach this problem in GAE?
Will launching my app inside VPC helps here?