Experience report: OSTree in our build system

[David Rothlisberger <david rothlis net>]

Traditional build systems like Make or Ninja can specify a dependency on
a file, but not on a whole tree. In our company's build system we commit
every intermediate build target to OSTree, and this gives our build
rules the ability to depend on an entire tree (directory). We do this by
creating an OSTree ref, and listing the ref itself (i.e. the file in
ostree/refs/heads/...) as a dependency of the build rule.

I have written this up in more detail here:
https://lwn.net/SubscriberLink/821367/c05df51aafbaa821/

Some aspects of this build system were discussed on this list a while
ago by my colleague William Manley:
- https://mail.gnome.org/archives/ostree-list/2018-October/msg00005.html
- https://mail.gnome.org/archives/ostree-list/2018-November/msg00000.html

- https://mail.gnome.org/archives/ostree-list/2018-December/msg00000.html

--David Rothlisberger.