First, I'm really excited to be working on https://deciphertools.com/support/ - our new Decipher Tools knowledgebase/faq. It will be linked into our site header when we fully replace the content from our old Freshdesk FAQ site. Second, I wanted to write a short post about using WordPress in Google App Engine (which is what we're using for aforementioned new faq), since setting it up gave me that cloudy head feeling like I don't know what I'm doing. Maybe the resources I found can help others avoid the cloudy head!
I worked from the pretty solid directions from the Google Cloud Platform team. This page links to their GitHub as well, but I started from the zip and then updated WordPress later after I got things running.
I'm a bit short on time, so for now, I'm just going to spew some things I learned and hopefully flesh it out later with more appropriate tutorial-like writing. (And since you're reading this now, clearly I have NOT done that yet!)
The instructions say this, but I'll repeat. Do all of your updates/upgrades locally and then once you're happy, push to GAE.
You'll need to setup a Google Storage bucket for media uploads. This bucket name is going to be part of your image url for all of your images on the site, so name it something nice and hopefully relevant to your WordPress site!
To get the dang plugin and theme install button to work on your local site on newer versions of the Google App Engine Launcher, you need to add the following to your php.ini file (which you made as part of the starter project tutorial). Kudos to this thread for that.
google_app_engine.disable_readonly_filesystem = 1
I still can't get the "update WordPress" button to work in my local instance, so I just downloaded the ZIP (using the github reference to WordPress from Google Cloud Platform's starter project github.) and manually copied files. Be sure you're copying subfolders properly, and not clobbering away your themes and plugins with empty subfolders :)
After updating to WordPress 4 (4.anything), my uploads no longer worked. I found this ticket and found the solution to add the following to your wp-config.php. I added it after the authentication keys and salts. Then, don't forget to clear your browser cookies for your local and live test site so you don't lose your mind (like I did).
// ADDED FOR GAE SUPPORT // https://code.google.com/p/googleappengine/issues/detail?id=11354 define('COOKIEPATH', '/');
I'm sure I'll think of more.