pbuilder: binary .debs in a clean chroot#

Builds binary .debs from the per-target source package using pbuilder in a minimal chroot, exactly as a Launchpad/buildd build would — per https://wiki.ubuntu.com/PbuilderHowto.

Generic across Debian and Ubuntu: packaging/deb/pbuild.sh (called by make pkg TARGET=<t>) builds this image with the target's BASE_IMAGE and runs it. The image picks the right archive keyring for its base, and pbuilderrc picks the right mirror/components from OS (ubuntu→archive.ubuntu.com, debian→deb.debian.org).

Usage (normally via the top-level Makefile)#

make pkg TARGET=ubuntu-26.04     # -> out/ubuntu-26.04/*.deb
make pkg TARGET=ubuntu-24.04
make pkg TARGET=debian-13

Each runs: docker build (BASE per target) → docker run --privileged → pbuilder create (first time) → pbuilder build *.dsc. Results are written to out/<target>/.

Important#

• --privileged is required — pbuilder builds in a chroot and needs mount/chroot; without it pbuilder create fails inside Docker.
• Network at run time — debootstrap fetches the base chroot and apt installs the Build-Depends. The OxCaml compile itself uses only the vendored sources in the orig, so it needs no network.
• Per-target cache: pbuild.sh mounts a oxcaml-pbuilder-cache-<t> named volume at /var/cache/pbuilder, so the slow pbuilder create is done once per distro.
• If a registry lacks e.g. ubuntu:26.04, override that target's BASE_IMAGE (edit packaging/targets/ubuntu-26.04.conf or pass BASE_IMAGE= on the make line).
• The build is the full flambda2 bootstrap — expect it to take a while in the clean chroot.

Files#