passt/test/README.md

Scope

This directory contains test cases for passt and pasta and a simple POSIX shell-based framework to define them, and run them as a suite.

These tests can be run as part of a continuous integration workflow, and are also used to provide short usage demos, with video recording, for passt and pasta basic use cases.

Run

Dependencies

Packages

The tests require some package dependencies commonly available in Linux distributions. If some packages are not available, the test groups that need them will be selectively skipped.

This is a non-exhaustive list of packages that might not commonly be installed on a system, i.e. common utilities such as a shell are not included here.

Example for Debian, and possibly most Debian-based distributions:

bats bc build-essential catatonit clang-tidy conmon cppcheck crun fakeroot
git go iperf3 isc-dhcp-common jq libgpgme-dev libseccomp-dev linux-cpupower
lm-sensors lz4 netavark netcat-openbsd psmisc qemu-efi-aarch64
qemu-system-arm qemu-system-misc qemu-system-ppc qemu-system-x86
qemu-system-x86 sipcalc socat strace tmux uidmap valgrind

NOTE: the tests need a qemu version >= 7.2, or one that contains commit 13c6be96618c ("net: stream: add unix socket"): this change introduces support for UNIX domain sockets as network device back-end, which qemu uses to connect to passt.

Other tools

Test measuring request-response and connect-request-response latencies use neper, which is not commonly packaged by distributions and needs to be built and installed manually:

git clone https://github.com/google/neper
cd neper; make
cp tcp_crr tcp_rr udp_rr /usr/local/bin

Virtual machine images are built during test executions using mbuto, the shell script is sourced via git as needed, so there's no need to actually install it.

Kernel parameters

Performance tests use iperf3 with rather large TCP receiving and sending windows, to decrease the likelihood of iperf3 itself becoming the bottleneck. These values need to be allowed by the kernel of the host running the tests. Example for /etc/sysctl.conf:

net.core.rmem_max = 134217728 net.core.wmem_max = 134217728

Further, the passt demo uses perf(1), relying on hardware events for performance counters, to display syscall overhead. The kernel needs to allow unprivileged users to access these events. Suggested entry for /etc/sysctl.conf:

kernel.perf_event_paranoid = -1

Special requirements for continuous integration and demo modes

Running the test suite as continuous integration or demo modes will record the terminal with the steps being executed, using asciinema(1), and create binary packages.

The following additional packages are commonly needed:

alien asciinema linux-perf tshark

Regular test

Just issue:

./run

from the test directory. Elevated privileges are not needed. Environment variable settings: DEBUG=1 enables debugging messages, TRACE=1 enables tracing (further debugging messages), PCAP=1 enables packet captures. Example:

PCAP=1 TRACE=1 ./run

Running selected tests

Rudimentary support to run a list of selected tests, without support for dependencies, is available. Tests need to have a setup function corresponding to their path. For example:

./run passt/ndp passt/dhcp pasta/ndp

will call the 'passt' setup function (from lib/setup), run the two corresponding tests, call the 'passt' teardown function, the 'pasta' setup, run the pasta/ndp test, and finally tear down the 'pasta' setup.

Note that requirements on steps implemented by related tests are not handled. For example, if the 'passt/tcp' needs guest connectivity set up by the 'passt/ndp' and 'passt/dhcp' tests, those need to be listed explicitly.

Continuous integration

Issuing:

./ci

will run the whole test suite while recording the execution, and it will also build JavaScript fragments used on http://passt.top/ for performance data tables and links to specific offsets in the captures.

Demo mode

Issuing:

./demo

will run the demo cases under demo, with terminal captures as well.

Framework

The implementation of the testing framework is under lib, and it provides facilities for terminal and tmux session management, interpretation of test directives, video recording, and suchlike. Test cases are organised in the remaining directories.

Test cases can be implemented as POSIX shell scripts, or as a set of directives, which are not formally documented here, but should be clear enough from the existing cases. The entry point for interpretation of test directives is implemented in lib/test.