Reproducible builds of ports

Hi,

I would like to know if there is any conceivable way to do independent 
reproducible builds of the ports tree packages today?

The biggest obstacle seems to be the fact that FreeBSD does not have a 
snapshot/archive repo equivalent to snapshot.debian.org.


My current approach is to fetch the .pkg, extract the ports_top_git_hash 
metadata, checkout the ports tree to that commit and run e.g. poudriere 
bulk -j "$JAIL" -p "$PORTS_TREE" "$ORIGIN"

But I am not sure how poudriere handles changes in port tree commit 
hash. If a next package comes in with a different ports_top_git_hash,

will poudriere be able to reuse any common dependencies that were 
already built or will it have to rebuild the whole tree again?

The latter scenario is obviously a huge resource waste and an automatic no.


My first question is whether my approach is generally sound for trying 
to reproduce a single package? If not, how should I correct my workflow?

My second one is for any workarounds or "close enough" techniques that 
would at least be able to reproduce some amount of packages. I'd be 
happy even with 10% reproducibility.


If I can find some path forward, I'd like to ultimately add FreeBSD 
support to rebuilderd, a cross-distro effort to make distro packages 
independently reproducible.


Best regards