Background
For years we've been needing a way to test podman upgrades; this became much more critical on December 7, 2020, when Matt disclosed a bug he had found over the weekend (#8613) in which reuse of a previously-defined field name would result in fatal JSON decode failures if current-podman were to try reading containers created with podman <= 1.8 (FIXME: confirm)
Upgrade testing is a daunting problem; but in the December 12 Cabal meeting Dan suggested using podman-in-podman. This PR is the result of fleshing out that idea.
Overview
The BATS script in this directory fetches and runs an old-podman container image from quay.io/podman, uses it to create and run a number of containers, then uses new-podman to interact with those containers.
Testing updates from versions earlier than v5.3.1 fails. Testing updates from tags that do not respect semantic versioning fails too (e.g. v5.6.0-immutable or v5.6). As of 2025-11-18 the available old-podman versions to test against are:
$ bin/podman search --list-tags --limit=400 quay.io/podman/stable | awk '$2 ~ /^v[0-9]+\.[0-9]+\.[0-9]+$/ { print $2}' | sort | awk '/v5.3.1/,0' | column -c 75
v5.3.1 v5.4.0 v5.4.2 v5.5.1 v5.6.0 v5.6.2
v5.3.2 v5.4.1 v5.5.0 v5.5.2 v5.6.1
Test invocation is:
$ sudo env PODMAN=bin/podman PODMAN_UPGRADE_FROM=v5.3.1 PODMAN_UPGRADE_TEST_DEBUG= bats test/upgrade
(Path assumes you're cd'ed to top-level podman repo). PODMAN_UPGRADE_FROM
can be any of the versions above. PODMAN_UPGRADE_TEST_DEBUG is empty
here, but listed so you can set it =1 and leave the podman_parent
container running. Interacting with this container is left as an
exercise for the reader.
The script will pull the given podman image, invoke it with a scratch root directory, and have it do a small set of podman stuff (pull an image, create/run some containers). This podman process stays running because if it exits, it kills containers running inside the container.
We then invoke the current (host-installed) podman, using the same scratch root directory, and perform operations on those images and containers. Most of those operations are done in individual @tests.
The goal is to have this upgrade test run in CI, iterating over a loop of known old versions. This list would need to be hand-maintained and updated on new releases. There might also need to be extra configuration defined, such as per-version commands (see below).
Findings
Well, first, v1.6.2 won't work on default f32/f33: the image
does not include crun, so it can't work at all:
ERRO[0000] oci runtime "runc" does not support CGroups V2: use system migrate to mitigate
I realize that it's kind of stupid not to test 1.6, since that's precisely the test that would've caught #8613 early, but I just don't think it's worth the hassle of setting up cgroupsv1 VMs.
For posterity, in an earlier incantation of this script I tried booting f32 into cgroupsv1 and ran into the following warnings when running new-podman on old-containers:
ERRO[0000] error joining network namespace for container 322b66d94640e31b2e6921565445cf0dade4ec13cabc16ee5f29292bdc038341: error retrieving network namespace at /var/run/netns/cni-577e2289-2c05-2e28-3c3d-002a5596e7da: failed to Statfs "/var/run/netns/cni-577e2289
Where To Go From Here
-
Tests are still (2021-02-23) incomplete, with several failing outright. See FIXMEs in the code.
-
Figuring out how/if to run rootless. I think this is possible, perhaps even necessary, but will be tricky to get right because of home-directory mounting.
-
Figuring out how/if to run variations with different config files (e.g. running OLD-PODMAN that creates a user libpod.conf, tweaking that in the test, then running NEW-PODMAN upgrade tests)