On 4/1/20 4:24 PM, Stephen Gallagher wrote:
On Wed, Apr 1, 2020 at 3:11 AM Panu Matilainen <pmatilai@xxxxxxxxxx> wrote:
On 3/31/20 3:34 PM, Stephen Gallagher wrote:
On Tue, Mar 31, 2020 at 8:10 AM Panu Matilainen <pmatilai@xxxxxxxxxx> wrote:
It's that time of year again... as our RPM change proposals passed with
flying colors in yesterdays meeting, I'll hope to land RPM 4.16 alpha in
rawhide later today or tomorrow by latest.
Since Panu left it out of his announcement, I'd also like to mention
that RPM 4.16 adds the following new feature:
"Add support for meta dependencies (eg Requires(meta): somepkg) that
do not affect install/erase ordering (RhBug:1648721)"
These dependencies are intended for use with metapackages and help
with avoiding dependency loops. Essentially, a `Requires(meta):`
dependency is telling RPM: at the end of any transaction where this
package is installed, this dependency must also be installed, but I
don't need the dependency ordered earlier.
This is going to come in handy for the Fedora Release packages (like
fedora-release-server) which will be able to define a minimal "API" to
be recognized as that Edition (or Spin). This didn't work before this
feature was added, because fedora-release must be ordered early in the
transaction to set up things like /etc/os-release, so we couldn't set
dependencies.
Oh, thanks for the reminder about this Stephen.
Besides meta-packages, another potential use-case for meta (whether
Requires or weak dependencies) is those just-in-case dependencies across
sub-packages to ensure nobody runs weird combinations even though
sonames might permit it. Often they are in the same direction as the
soname dependency so it doesn't create any additional ordering issues
but sometimes they're in the opposite direction, creating a wholly
unnecessary dependency loop. Rpm itself is an example of this (but we
can't really use "meta" anytime soon as rpm needs to be bootstrappable
from older versions)
Do you mean things like:
Requires: libfoo >= 3.4.2-3
could become
Requires(meta): libfoo >= 3.4.2-3
What about things like ensuring that subpackages are running the same
version as the main package so they get updated together?
This latter case is what I meant by the above, apparently not very
clearly :)
Care needs to be taken though when adding "meta" to things like this as
in many cases the order *does* matter.
- Panu -
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