Is the server portion of freebsd-update open source?

[Nielsen]

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I'm wondering if/where I can get the server side component for
freebsd-update. Presumably such a component would build and sign the
binary patches and prepare them to be served via HTTP to the
freebsd-update client.

I need a system for distributing binary updates to a collection of
customized FreeBSD machines, jails, and embedded systems. freebsd-update
seems to be what I'm looking for, but I'm wondering if the server side
is a proprietary piece of technology held by someone somewhere, or if it
is in fact open source.

Any pointers on where the project would be hosted if it is open source?
The few leads that turned up when searching google ended up being dead ends.

Thanks,
Nate
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