python managed VMs success story! (so far...)

[Adam Sah]

My 5+ year old GAE/Python app migrated to Managed VMs (MVM) flawlessly!  (enterprise app with 15,000+ users doing all sorts of different things - not a simple website)

easy upgrade:

 - minimal code changes - just changed app.yaml and our deploy scripts

 - deploys into a new "version" of the same dev/staging/production instances as non-MVM GAE, i.e. share backup/restore, one click to split/migrate traffic, etc

 - one click to rollback

 - can upgrade some modules and not others; if you're still using backends, they can stay on native GAE.  Example: cron.yaml jobs can still run on GAE native if you want.

lots of immediate wins:

 - 30-300% performance boost (depending on the activity, of course - I/O bound not so much)

 - immediate $$$ savings 

 - not limited to 1GB RAM and in fact it starts with 1.7GB.

 - not limited to slow or single core CPUs

lots of roadmap wins:

 - native libraries

 - python3

 - can SSH into live instance(s) -- though admittedly, I haven't figured out the value yet...

wrinkles:

 - deploy time is much slower -- 8+ mins

 - auto-scaling is a lot slower, i.e. in practice users may get 502 errors if you don't provision correctly - even with auto-scaling

 - logs are more detailed but harder to read - native GAE had nice simple stack traces

 - deploys to one zone/region for now -- native GAE was multi-homed

 - docs were incomplete, e.g. didn't mention needing to push cron.yaml, index.yaml

 - error messages are incomplete, e.g. queue.yaml needs to be precisely named that (where other yaml files can have any name)

hope this helps,   (and feedback welcome)

adam

[Adam Sah]

quick followup and a good example of how it's easy to run components side-by-side:

 - Image processing (PIL) doesn't work yet - bummer because my app resizes its images.

 - but no problem!  I just setup a 302 redirect back to the old app version, which still runs on demand! (or use urlfetch or ...)

adam

[Jon Parrott]

Hey Adam, thanks for the great feedback.

Can you give me a bit more details on PIL not working for you? Which runtime are you using?

[Adam Sah]

Actually, I misspoke - it's the Images API that's the trouble, which was covered elsewhere: https://groups.google.com/forum/#!topic/google-appengine/jdwYig9smJI
   (just need to update the GAE/MVM docs to mention this explicitly, and ideally detect if an app might be using this 

Currently, I'm fighting with the timezone issue: https://groups.google.com/forum/#!topic/google-appengine/8vob1UfnRpY

adam