compose: Drop rpmdb sqlite journaling files if rpmdb-normalize

[cgwalters]

See rpm-software-management/rpm#2219
This is one of the things that makes builds unreproducible in
general, which is worth fixing alone.

But the thing immediately driving this now for me is that I
think we're getting some ill-defined behavior because we
may have these files hardlinked (via ostree) and depending
on the container build environment, we may or may not see
modifications "through" the hardlink:
https://docs.kernel.org/filesystems/overlayfs.html#index

If we happen to mutate the rpmdb.sqlite-shm file in
one path but not the other confusion could easily result.

(Actually what we want to do really is drop our other
hardlinked copies of the rpmdb entirely, but that's
a bigger change)

Out of conservatism for now, we only do this if
rpmdb-normalize is set (which none of the Fedora derivatives
set today AFAICS). I do think we should likely
do this in client side layering too, but this
reduces the blast radius for now.
I plan to enable this in fedora-bootc.

Signed-off-by: Colin Walters walters@verbum.org

---

[cgwalters]

This code affects all the places we write the rpmdb, from builds to client layering, so it has a decently high blast radius.

I am considering scoping something just to builds under the normalize_rpmdb key we already have that is opt-in (and not many are opting in).

[cgwalters]

Moved the prep PR to #5247

[cgwalters]

I am considering scoping something just to builds under the normalize_rpmdb key we already have that is opt-in (and not many are opting in).

Done

[cgwalters]

This one should be really safe, can someone stamp it?

[cgwalters]

For reference here's what I'd apply to the bootc base image with this

diff --git a/base/postprocess-conf.yaml b/base/postprocess-conf.yaml
index d11f4ee..610c83d 100644
--- a/base/postprocess-conf.yaml
+++ b/base/postprocess-conf.yaml
@@ -6,12 +6,9 @@ opt-usrlocal: "root"
 # https://github.com/CentOS/centos-bootc/issues/167
 machineid-compat: true
 
-# Note that the default for c9s+ is sqlite; we can't rely on rpm being
-# in the target (it isn't in tier-0!) so turn this to host here.  This
-# does break the "hermetic build" aspect a bit.  Maybe eventually
-# what we should do is special case this and actually install RPM temporarily
-# and then remove it...
-rpmdb: host
+rpmdb: target
+# Avoid hardlinking rpmdb.sqlite files
+rpmdb-normalize: true
 
 ignore-removed-users:
   - root
-- 
2.47.0

[cgwalters]

OK review is slow on this and I decided for now to just do this in the base image build in shell script https://gitlab.com/fedora/bootc/base-images/-/merge_requests/81/diffs?commit_id=e6f0334d328a8b01dc1191261a68c693e1b3205a

[jmarrero]

/lgtm