Hi, I think user_data is probably reasonably common - most people who use, eg, cloud-init will use it (we do).
As the 64k limit is a MySQL limitation, and not a nova limitation, why not just say, "if you want more storage, use postgres" (or similar)? I have no issue with making the size guarded in the application, with a configurable limit, but the particular problem that started this off is an implementation issue rather than a code issue. Storing the user_data in some place like the database is fairly important for making things like launch configs for autoscale groups work. I'd like to not make that harder to implement. Cheers, On Mon, 2012-08-13 at 09:12 -0400, Dan Prince wrote: > > ----- Original Message ----- > > From: "Michael Still" <michael.st...@canonical.com> > > To: openstack@lists.launchpad.net, openstack-operat...@lists.openstack.org > > Sent: Saturday, August 11, 2012 5:12:22 AM > > Subject: [Openstack] [Nova] How common is user_data for instances? > > > > Greetings. > > > > I'm seeking information about how common user_data is for instances > > in > > nova. Specifically for large deployments (rackspace and HP, here's > > looking at you). What sort of costs would be associated with changing > > the data type of the user_data column in the nova database? > > > > Bug 1035055 [1] requests that we allow user_data of more than 65,535 > > bytes per instance. Note that this size is a base64 encoded version > > of > > the data, so that's only a bit under 50k of data. This is because the > > data is a sqlalchemy Text column. > > > > We could convert to a LongText column, which allows 2^32 worth of > > data, > > but I want to understand the cost to operators of that change some > > more. > > Is user_data really common? Do you think people would start uploading > > much bigger user_data? Do you care? > > Nova has configurable quotas on most things so if we do increase the size of > the DB column we should probably guard it in a configurable manner with > quotas as well. > > My preference would actually be that we go the other way though and not have > to store user_data in the database at all. That unfortunately may not be > possible since some images obtain user_data via the metadata service which > needs a way to look it up. Other methods of injecting metadata via disk > injection, agents and/or config drive however might not need it to be store > in the database right? > > As a simpler solution: > > Would setting a reasonable limit (hopefully smaller) and returning a HTTP 400 > bad request if incoming requests exceed that limit be good enough to resolve > this ticket? That way we don't have to increase the DB column at all and end > users would be notified up front that user_data is too large (not silently > truncated). They way I see it user_data is really for bootstrapping > instances... we probably don't need it to be large enough to write an entire > application, etc. > > > > > > Mikal > > > > 1: https://bugs.launchpad.net/nova/+bug/1035055 > > > > _______________________________________________ > > Mailing list: https://launchpad.net/~openstack > > Post to : openstack@lists.launchpad.net > > Unsubscribe : https://launchpad.net/~openstack > > More help : https://help.launchpad.net/ListHelp > > > > _______________________________________________ > Mailing list: https://launchpad.net/~openstack > Post to : openstack@lists.launchpad.net > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp -- Stephen Gran Senior Systems Integrator - guardian.co.uk Please consider the environment before printing this email. ------------------------------------------------------------------ Visit guardian.co.uk - newspaper of the year www.guardian.co.uk www.observer.co.uk www.guardiannews.com On your mobile, visit m.guardian.co.uk or download the Guardian iPhone app www.guardian.co.uk/iphone and iPad edition www.guardian.co.uk/iPad Save up to 37% by subscribing to the Guardian and Observer - choose the papers you want and get full digital access. Visit guardian.co.uk/subscribe --------------------------------------------------------------------- This e-mail and all attachments are confidential and may also be privileged. If you are not the named recipient, please notify the sender and delete the e-mail and all attachments immediately. Do not disclose the contents to another person. You may not use the information for any purpose, or store, or copy, it in any way. Guardian News & Media Limited is not liable for any computer viruses or other material transmitted with or as part of this e-mail. You should employ virus checking software. Guardian News & Media Limited A member of Guardian Media Group plc Registered Office PO Box 68164 Kings Place 90 York Way London N1P 2AP Registered in England Number 908396 _______________________________________________ Mailing list: https://launchpad.net/~openstack Post to : openstack@lists.launchpad.net Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp
