F36 Change: Podman 4.0 (Late Self-Contained Change)

[Ben Cotton]

(Process note: this proposal is well past the deadline, but after
consulting with FESCo members, I am announcing it anyway, since it is
a leaf package that should have no impact on other
developers/maintainers)

https://fedoraproject.org/wiki/Changes/Podman4.0

== Summary ==
Podman 4.0 will be released in Fedora 36 for the first time.

== Owner ==
* Name: Dan Walsh
* Email: dwalsh(a)fedoraproject.org


== Detailed Description ==
Podman 4.0 will be fully released for the first time in Fedora 36. The
API has had breaking changes so it will not be released to stable in
Fedora 34 or Fedora 35. Podman 4.0 has a huge amount of changes and a
brand new network stack.


== Benefit to Fedora ==
Podman 4.0 has a huge list of new features, highlighted by a brand new
network stack. Lots of improvements and bug fixes.

See more here: https://github.com/containers/podman/releases/tag/v4.0.0-rc2


== Scope ==
* Proposal owners: It is in RC2, now, so just complete the release.

* Other developers: N/A
* Release engineering:
* Policies and guidelines: N/A (not needed for this Change)
* Trademark approval: N/A (not needed for this Change)
* Alignment with Objectives:


== Upgrade/compatibility impact ==
Podman 3.* release will not be able to connect to Podman 4.0 via
remote API, similarly Podman 4.0 will not be able to connect to Podman
3.* API.

Existing network stack will continue to run, on existing systems.  All
containers and images need to be removed to try out the new network
stack.


== How To Test ==
Just test on existing systems. All Podman containers and images should
continue to work. And all compatibility API (docker-compose,
docker.py) should continue to work.


== User Experience ==


== Dependencies ==


== Contingency Plan ==
* Contingency mechanism: (What to do?  Who will do it?) N/A (not a
System Wide Change)
* Contingency deadline: N/A (not a System Wide Change)
* Blocks release? N/A (not a System Wide Change)


== Documentation ==
N/A (not a System Wide Change)


-- 
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis

[Timothée Ravier]

Hi everyone,

First of all, thanks a lot for all the work that went into podman v4. The release notes
looks great and full of interesting changes!

As I understand it, the podman client and server remote API are version locked: podman v3
clients can only speak with podman v3 servers, v4 clients with v4 servers. I think that
this situation creates the need for a transition period between the two versions, where v3
& v4 are made available at the same time in Fedora 35 and 36.

Users might be running podman on a variety of distributions as client (Fedora, etc.) and
similarly as servers (Fedora CoreOS, Fedora Server, CentOS Stream, etc.). It is thus
likely that they will need to be able to interact with podman v3 and v4 servers for some
time until podman v4 is available everywhere. Having the podman v3 and v4
"client" packages available and co-installable in both Fedora 35 and 36 would
help with the transition.

For example, there could be a podman4 package in F35 and a podman3 package in F36. This
would create an automatic upgrade path for the un-versioned podman package during the
F35->36 upgrade for the local use case. Users would also be able to install the other
podman version in case they needed to talk to a remote server.

For Fedora CoreOS, providing co-installable "server" packages for podman v3 and
v4 in Fedora 35 & 36 would enable us to ship both versions directly in the Fedora
CoreOS image and thus create a nice transition period for users where they could select
their preferred version on first boot.

Note that I'm only advocating for co-installation, not co-usage of both podman v3 and
v4. The "alternative" podman package would ship with renamed service units and
binaries but everything else would be kept as is (only one TCP/UNIX socket for the
service, etc.).

This would also make it easier to test the new podman release and features by opting-in
podman v4 on Fedora 35.

Thanks,