Re: [PATCH v4 3/3] test: Convert build tests to exeter

[David Gibson <david@gibson.dropbear.id.au>]

[-- Attachment #1: Type: text/plain, Size: 8047 bytes --]

On Wed, Aug 20, 2025 at 12:40:44PM +0200, Stefano Brivio wrote:
> On Wed, 20 Aug 2025 13:10:02 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > On Tue, Aug 19, 2025 at 04:27:54PM +0200, Stefano Brivio wrote:
> > > On Thu,  7 Aug 2025 21:32:37 +1000
> > > David Gibson <david@gibson.dropbear.id.au> wrote:
> > >   
> > > > Convert the tests in build/all to be based on exeter.  The new version of
> > > > the tests is more robust than the original, since it makes a temporary copy
> > > > of the source tree so will not be affected by concurrent manual builds.
> > > > 
> > > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > > > ---
> > > >  test/build/all      | 61 --------------------------------
> > > >  test/build/build.py | 84 +++++++++++++++++++++++++++++++++++++++++++++
> > > >  test/run            |  8 ++---
> > > >  3 files changed, 88 insertions(+), 65 deletions(-)
> > > >  delete mode 100644 test/build/all
> > > >  create mode 100755 test/build/build.py
> > > > 
> > > > diff --git a/test/build/all b/test/build/all
> > > > deleted file mode 100644
> > > > index 1f79e0d8..00000000
> > > > --- a/test/build/all
> > > > +++ /dev/null
> > > > @@ -1,61 +0,0 @@
> > > > -# SPDX-License-Identifier: GPL-2.0-or-later
> > > > -#
> > > > -# PASST - Plug A Simple Socket Transport
> > > > -#  for qemu/UNIX domain socket mode
> > > > -#
> > > > -# PASTA - Pack A Subtle Tap Abstraction
> > > > -#  for network namespace/tap device mode
> > > > -#
> > > > -# test/build/all - Build targets, one by one, then all together, check output
> > > > -#
> > > > -# Copyright (c) 2021 Red Hat GmbH
> > > > -# Author: Stefano Brivio <sbrivio@redhat.com>
> > > > -
> > > > -htools	make cc rm uname getconf mkdir cp rm man
> > > > -
> > > > -test	Build passt
> > > > -host	make clean
> > > > -check	! [ -e passt ]
> > > > -host	CFLAGS="-Werror" make passt
> > > > -check	[ -f passt ]
> > > > -
> > > > -test	Build pasta
> > > > -host	make clean
> > > > -check	! [ -e pasta ]
> > > > -host	CFLAGS="-Werror" make pasta
> > > > -check	[ -h pasta ]
> > > > -
> > > > -test	Build qrap
> > > > -host	make clean
> > > > -check	! [ -e qrap ]
> > > > -host	CFLAGS="-Werror" make qrap
> > > > -check	[ -f qrap ]
> > > > -
> > > > -test	Build all
> > > > -host	make clean
> > > > -check	! [ -e passt ]
> > > > -check	! [ -e pasta ]
> > > > -check	! [ -e qrap ]
> > > > -host	CFLAGS="-Werror" make
> > > > -check	[ -f passt ]
> > > > -check	[ -h pasta ]
> > > > -check	[ -f qrap ]
> > > > -
> > > > -test	Install
> > > > -host	mkdir __STATEDIR__/prefix
> > > > -host	prefix=__STATEDIR__/prefix make install
> > > > -check	[ -f __STATEDIR__/prefix/bin/passt ]
> > > > -check	[ -h __STATEDIR__/prefix/bin/pasta ]
> > > > -check	[ -f __STATEDIR__/prefix/bin/qrap ]
> > > > -check	man -M __STATEDIR__/prefix/share/man -W passt
> > > > -check	man -M __STATEDIR__/prefix/share/man -W pasta
> > > > -check	man -M __STATEDIR__/prefix/share/man -W qrap
> > > > -
> > > > -test	Uninstall
> > > > -host	prefix=__STATEDIR__/prefix make uninstall
> > > > -check	! [ -f __STATEDIR__/prefix/bin/passt ]
> > > > -check	! [ -h __STATEDIR__/prefix/bin/pasta ]
> > > > -check	! [ -f __STATEDIR__/prefix/bin/qrap ]
> > > > -check	! man -M __STATEDIR__/prefix/share/man -W passt 2>/dev/null
> > > > -check	! man -M __STATEDIR__/prefix/share/man -W pasta 2>/dev/null
> > > > -check	! man -M __STATEDIR__/prefix/share/man -W qrap 2>/dev/null
> > > > diff --git a/test/build/build.py b/test/build/build.py
> > > > new file mode 100755
> > > > index 00000000..12bb82d8
> > > > --- /dev/null
> > > > +++ b/test/build/build.py
> > > > @@ -0,0 +1,84 @@
> > > > +#! /usr/bin/env python3
> > > > +#
> > > > +# SPDX-License-Identifier: GPL-2.0-or-later
> > > > +#
> > > > +# PASST - Plug A Simple Socket Transport
> > > > +#  for qemu/UNIX domain socket mode
> > > > +#
> > > > +# PASTA - Pack A Subtle Tap Abstraction
> > > > +#  for network namespace/tap device mode
> > > > +#
> > > > +# test/build/build.py - Test build and install targets
> > > > +#
> > > > +# Copyright Red Hat
> > > > +# Author: David Gibson <david@gibson.dropbear.id.au>
> > > > +
> > > > +import contextlib
> > > > +import os
> > > > +from pathlib import Path
> > > > +import subprocess
> > > > +import tempfile
> > > > +from typing import Iterable, Iterator
> > > > +
> > > > +import exeter
> > > > +
> > > > +def sh(cmd):
> > > > +    subprocess.run(cmd, shell=True)
> > > > +
> > > > +
> > > > +@contextlib.contextmanager
> > > > +def clone_sources() -> Iterator[str]:
> > > > +    os.chdir('..')  # Move from test/ to repo base
> > > > +    with tempfile.TemporaryDirectory(ignore_cleanup_errors=False) as tmpdir:  
> > > 
> > > I guess I see the advantage of this syntax, it's still a bit less
> > > obvious to me than a mere sequence of steps and an explicit cleanup
> > > function.  
> > 
> > I agree that it's less obvious, but I think the advantages are worth
> > it.  Namely that it will correctly run the cleanup in nearly all cases
> > of an interrupted test (not a SIGKILL, obviously).
> > 
> > Arguably, it's not a good trade off in this simple case.  However once
> > we get to real network tests, it's pretty common to have multiple
> > nested layers of setup, each with their own teardown.  Sometimes you
> > need something torn down, but it's only set up partway through the
> > test, or you want something for the first part of the test but not
> > after, so it needs to be torn down only if interrupted at certain
> > points.  Manually keeping track of that quickly becomes really
> > painful, I really want to use this technique there.
> 
> Another idea (I'm not sure if it makes this useless, but we probably
> want to implement it anyway) is what nft tests (and some kselftests) do
> nowadays: every test runs in its own network namespace, so you don't
> need an explicit teardown. The kernel already tracks things for you.

Right, I'm planning to implement that in tunbridge.  Unlike the
earlier drafts, my intention is that all the namespaces / whatever you
explicitly create will be nested inside a top-level sandboxing
namespace.

I don't think it obviates the use for context managers, though.  For
one thing I think we may have occasional need for things that won't be
handled by the normal sandbox, but the contextmanager can handle those
too.  More widely, there are cases where you want to tear something
down partway through normal test operation.  The context manager will
do that neatly, while also doing the teardown if interrupted before
that point.

> If you combine that with what pasta does (same as container runtimes
> really), you could get something that's also robust to SIGKILL, by
> making every test "parent" process (assuming there can be one) PID 1 in
> its own PID namespace.

Right, it can sometimes make things more confusing during debugging,
though.

> Add mount namespaces on top, with tmpfs, and we probably don't even
> need to clean up after ourselves in build tests.
> 
> Yes, it could be called a container but it's probably useful to retain
> tight control of what namespace we detach and when.
> 
> Given that pasta(1) is now available on any distribution where you
> might reasonably find Python, by the way, you could consider using it
> directly (the installed version, that is) if it helps.

I don't really want to.  I consider the test cases being entirely cut
off from the outside internet an advantage, in most cases.

> > Given that I intend to use it there, I think it makes sense to use it
> > here too: after all it will be even less obvious if there are only
> > hard examples of it and no easy ones.
> 
> Ah, sure, fair point.

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]