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increasing size of user data in nova api

asked 2019-04-25 14:58:38 -0500

sudobasher gravatar image

hello there! doing a bit of research into increasing the size of user data that can be ingested into the the openstack nova api. currently it looks to be limited at 64 kB, due to the mysql/maria db limitation of the nova_api db > flavors table > description column text type

been searching through the openstack universe to see where potential database upgrades should be submitted to the upstream community, whether via sqlalchemy or other tool, etc., but i'm not sure whether the sql schema is defined and created via code when provisioning openstack.

question 1: where does this sql schema code live?

question 2: where would be the best place to submit a contribution to add this upgraded feature of a bigger column value?

question 3: in terms of community reception, do i need to submit changes for both normal openstack and devstack code bases, or just one?

note: for the moment, i'd like to focus only on the nova api improvement, and not address the 16 kB limitation in the devstack horizon web interface.

think i found the relevant code in the nova api python app codebase itself already.

thank you for the help!

.: sudobasher

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If you don't get an answer here, I suggest you either use the openstack mailing list (put [nova] in the subject, with square brackets) or the chat channel. This is an inclusive or :)

And see

Bernd Bausch gravatar imageBernd Bausch ( 2019-04-25 18:40:57 -0500 )edit

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answered 2019-05-07 19:33:27 -0500

zaneb gravatar image

The SQL schema is here, and to update it you'll also need to add a new DB migration.

The limit is almost certainly entirely unrelated to the size of a flavor description; I would start by looking at the user_data field in the Instance table.

You should probably be aware that the chances of any change to the limit being accepted upstream are... indistinguishable from zero, though of course you're welcome to try.

Devstack is a collection of shell scripts for building an OpenStack installation for testing purposes, and is not related to your issue.

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@zaneb thank you! some very helpful links & thx for the course correction on the db schema. with the alt options of config drives & vendor data dynamic JSON (deployer data?), is that the basis of the upstream team not likely accepting this sort of change? would be great to hear a bit more about this

sudobasher gravatar imagesudobasher ( 2019-05-08 11:56:42 -0500 )edit

I'm not a member of the Nova team, but: you have to have some limit, and somebody will always want to go over it; 64k is already quite generous (AWS allows only 16k); it's been like this ~forever and nothing bad has happened.

zaneb gravatar imagezaneb ( 2019-05-15 15:08:03 -0500 )edit

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Asked: 2019-04-25 14:58:38 -0500

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Last updated: May 07