Martin Roukala (né Peres)
70057c8b47
Until Podman v4.3, privileged rootfull containers would expose all the host devices to the container while rootless ones would exclude `/dev/ptmx` and `/dev/tty*`. When5a2405ae1b("Don't mount /dev/tty* inside privileged containers running systemd") landed, rootfull containers started excluding all the `/dev/tty*` devices when the container would be running in systemd mode, reducing the disparity between rootless and rootfull containers when running in this mode. However, this commit regressed some legitimate use cases: exposing non-virtual-terminal tty devices (modems, arduinos, serial consoles, ...) to the container, and the regression was addressed inf4c81b0aa5("Only prevent VTs to be mounted inside privileged systemd containers"). This now calls into question why all tty devices were historically prevented from being shared to the rootless non-privileged containers. A look at the podman git history reveals that the code was introduced as part ofba430bfe5e("podman v2 remove bloat v2"), and obviously was copy-pasted from some other code I couldn't find. In any case, we can easily guess that this check was put for the same reason5a2405ae1bwas introduced: to prevent breaking the host environment's consoles. This also means that excluding *all* tty devices is overbearing, and should instead be limited to just virtual terminals like we do on the rootfull path. This is what this commit does, thus making the rootless codepath behave like the rootfull one when in systemd mode. This leaves `/dev/ptmx` as the main difference between the two codepath. Based on the blog post from the then-runC maintainer[1] and this Red Hat bug[2], I believe that this is intentional and a needed difference for the rootless path. Closes: #16925 Suggested-by: Fabian Holler <mail@fholler.de> Signed-off-by: Martin Roukala (né Peres) <martin.roukala@mupuf.org> [1]: https://www.cyphar.com/blog/post/20160627-rootless-containers-with-runc [2]: https://bugzilla.redhat.com/show_bug.cgi?id=501718
Quick overview of podman system tests. The idea is to use BATS, but with a framework for making it easy to add new tests and to debug failures.
Quick Start
Look at 030-run.bats for a simple but packed example. This introduces the basic set of helper functions:
-
setup(implicit) - resets container storage so there's one and only one (standard) image, and no running containers. -
parse_table- you can define tables of inputs and expected results, then read those in awhileloop. This makes it easy to add new tests. Because bash is not a programming language, the caller ofparse_tablesometimes needs to massage the returned values;015-run.batsoffers examples of how to deal with the more typical such issues. -
run_podman- runs command defined in$PODMAN(default: 'podman' but could also be './bin/podman' or 'podman-remote'), with a timeout. Checks its exit status. -
is- compare actual vs expected output. Emits a useful diagnostic on failure. -
die- output a properly-formatted message to stderr, and fail test -
skip_if_rootless- if rootless, skip this test with a helpful message. -
skip_if_remote- like the above, but skip if testingpodman-remote -
random_string- returns a pseudorandom alphanumeric string
Test files are of the form NNN-name.bats where NNN is a three-digit
number. Please preserve this convention, it simplifies viewing the
directory and understanding test order. In particular, 00x tests
should be reserved for a first-pass fail-fast subset of tests:
bats test/system/00*.bats || exit 1
bats test/system
...the goal being to provide quick feedback on catastrophic failures without having to wait for the entire test suite.
Running tests
To run the tests locally in your sandbox, you can use one of these methods:
- make;PODMAN=./bin/podman bats ./test/system/070-build.bats # runs just the specified test
- make;PODMAN=./bin/podman bats ./test/system # runs all
- make;PODMAN=./bin/podman NETWORK_BACKEND=netavark bats ./test/system # Assert & enable netavark testing
To test as root:
- $ PODMAN=./bin/podman sudo --preserve-env=PODMAN bats test/system
Analyzing test failures
The top priority for this scheme is to make it easy to diagnose
what went wrong. To that end, podman_run always logs all invoked
commands, their output and exit codes. In a normal run you will never
see this, but BATS will display it on failure. The goal here is to
give you everything you need to diagnose without having to rerun tests.
The is comparison function is designed to emit useful diagnostics,
in particular, the actual and expected strings. Please do not use
the horrible BATS standard of [ x = y ]; that's nearly useless
for tracking down failures.
If the above are not enough to help you track down a failure:
Debugging tests
Some functions have dprint statements. To see the output of these,
set PODMAN_TEST_DEBUG="funcname" where funcname is the name of
the function or perhaps just a substring.
Requirements
The jq tool is needed for parsing JSON output.
Further Details
TBD. For now, look in helpers.bash; each helper function
has (what are intended to be) helpful header comments. For even more
examples, see and/or run helpers.t; that's a regression test
and provides a thorough set of examples of how the helpers work.