[Nova] Increase size limits for user data

Flavio Percoco flavio at redhat.com
Tue Dec 4 11:08:08 UTC 2018


Greetings,

I've been working on a tool that requires creating CoreOS nodes on
OpenStack. Sadly, I've hit the user data limit, which has blocked the
work I'm doing.

One big difference between CoreOS images and other cloud images out
there is that CoreOS images don't use cloud-init but a different tool
called Ignition[0], which uses JSON as its serialization format.

The size of the configs that I need to pass to the instance is bigger
than the limit imposed by Nova. I've worked on reducing the size as
much as possible and even generating a compressed version of it but
the data is still bigger than the limit (144 kb vs 65kb).

I'd like to understand better what the nature of the limit is (is it
because of the field size in the database? Is it purely an API limit?
Is it because it causes problems depending on the vendor? As far as I
can tell the limit is just being enforced by the API schema[1] and not
the DB as it uses a MEDIUMTEXT field.

I realize this has been asked before but I wanted to get a feeling of
the current opinion about this. Would the Nova team consider
increasing the limit of the API considering that more use cases like
this may be more common these days?

[0] https://coreos.com/ignition/docs/latest/
[1] https://github.com/openstack/nova/blob/master/nova/api/openstack/compute/schemas/servers.py#L212-L215

Thanks,
Flavio

-- 
@flaper87
Flavio Percoco



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