podman/test/upgrade/README.md

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.

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)