This is because rpm-ostree by default doesn't allow writing to `/var` from scriptlets. For more information on this and other rpm-ostree "adaptations" required, see https://bugzilla.redhat.com/show_bug.cgi?id=1352154 and https://bugzilla.redhat.com/show_bug.cgi?id=1703203#c1.

In this case, offhand, it seems like pcp would need to be adapted as such:
- tmpfiles entries to create necessary dirs under /var
- run whatever rebuild scripts needed at startup time, rather than %post time

*** Bug 1717966 has been marked as a duplicate of this bug. ***

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I think this is still an issue, right? Re-opening.

Re those errors:

> Apr 23 11:12:08 localhost.localdomain rpm-ostree(pcp.post)[1945]: touch: cannot touch '/var/lib/pcp/pmns/.NeedRebuild': No such file or directory
> Apr 23 11:12:08 localhost.localdomain rpm-ostree(pcp.post)[1945]: chmod: cannot access '/var/lib/pcp/pmns/.NeedRebuild': No such file or directo>

I see in the spec file that it's likely from:

> %{install_file "$PCP_PMNS_DIR" .NeedRebuild}

which expands to:

> %global install_file() %{expand:
> if [ -w "%1" ]
> then
>     (cd "%1" && touch "%2" && chmod 644 "%2")
> else
>     echo "WARNING: Cannot write to %1, skipping %2 creation." >&2
> fi
> }

And that later on will trigger the `Rebuild` script to run? So in other words, we always want to run the `Rebuild` script whenever we drop in new binaries in case things need rebuilding?

If it's cheap to determine whether a rebuild is needed, then we could have a systemd service ordered before the PCP services do the check and potential rebuild. While this should work for both OSTree-based and traditional systems, we can keep doing it at post time for the latter if wanted by keying off of `test -f /run/ostree-booted`.

Thanks for those notes Jonathan - the spec snippet you're looking at has changed since this BZ was opened, and the runtime situation is more complex than triggering rebuild outside of rpm install (this already is done, and the issues in this original BZ are actually now resolved since pcp-5.1.0 - there are many issues remaining for us though).

We're trying to figure out how to make PCP and ostree play nicely over in 1827441 now (do I've DUP'd this one there), and upstream in https://github.com/performancecopilot/pcp/issues/816

*** This bug has been marked as a duplicate of bug 1827441 ***