Re: [PATCH 0/7] python: create installable package

[Vladimir Sementsov-Ogievskiy]

For patches 05-07:

Reviewing such patch is a strange thing: Pipfile changes are obvious enough, 
just select some version (I can't be sure about correct version choice, just 
believe in your commit messages). But what for Pipfile.lock? I can state that 
it's about package set selecting, Pipfile.lock looks like what it should be, 
but I have idea about all these packages, their versions and hashes (and even, 
does it correspond really to Pipfile or not) :)

Ha, what I can check, is: does pipenv create almost same Pipfile.lock in my 
environment (with 3.7.5 python)
OK, I've tried (pipenv lock --dev --python /usr/bin/python3), and yes, result 
is almost the same. For mypy and importlib-metadata packages I have newer 
version and different hashes (of course). Other packages are the same. Set of 
packages is the same.

Hmm, but in may generated Pipfile.lock there no "markers". They are about python version and looks 
like "markers": "python_version >= '3.5'".. Does pipenv follow them? Then why they are 
not generated for me, did you use some additional command/option to create them?
Anyway, they don't look dangerous, so for last three patches:
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

03.06.2020 03:15, John Snow wrote:
> Based-on: 20200602214528.12107-1-jsnow@redhat.com
>
> This series factors the python/qemu directory as an installable
> module. As a developer, you can install this to your virtual environment
> and then always have access to the classes contained within without
> needing to wrangle python import path problems.
>
> When developing, you could go to qemu/python/ and invoke `pipenv shell`
> to activate a virtual environment within which you could type `pip
> install -e .` to install a special development version of this package
> to your virtual environment. This package will always reflect the most
> recent version of the source files in the tree.
>
> When not developing, you could install a version of this package to your
> environment outright to gain access to the QMP and QEMUMachine classes
> for lightweight scripting and testing.
>
> This package is formatted in such a way that it COULD be uploaded to
> https://pypi.org/project/qemu and installed independently of qemu.git
> with `pip install qemu`, but of course that button remains unpushed.
>
> There are a few major questions to answer first:
>
> - What versioning scheme should we use? See patch 2.
>
> - Should we use a namespace package or not?
>    - Namespaced: 'qemu.machine', 'qemu.monitor' etc may be separately
>      versioned, packaged and distributed packages. Third party authors
>      may register 'qemu.xxx' to create plugins within the namespace as
>      they see fit.
>
>    - Non-namespaced: 'qemu' is one giant glob package, packaged and
>      versioned in unison. We control this package exclusively.
>
> - How do we eliminate sys.path hacks from the rest of the QEMU tree?
>    (Background: sys.path hacks generally impede the function of static
>    code quality analysis tools like mypy and pylint.)
>
>    - Simplest: parent scripts (or developer) needs to set PYTHONPATH.
>
>    - Harder: Python scripts should all be written to assume package form,
>      all tests and CI that use Python should execute within a VENV.
>
>    In either case, we lose the ability (for many scripts) to "just run" a
>    script out of the source tree if it depends on other QEMU Python
>    files. This is annoying, but as the complexity of the Python lib
>    grows, it is unavoidable.
>
>    In the VENV case, we at least establish a simple paradigm: the scripts
>    should work in their "installed" forms; and the rest of the build and
>    test infrastructure should use this VENV to automatically handle
>    dependencies and path requirements. This should allow us to move many
>    of our existing python scripts with "hidden" dependencies into a
>    proper python module hierarchy and test for regressions with mypy,
>    flake8, pylint, etc.
>
>    (We could even establish e.g. Sphinx versions as a dependency for our
>    build kit here and make sure it's installed to the VENV.)
>
>    Pros: Almost all scripts can be moved under python/qemu/* and checked
>    with CQA tools. imports are written the same no matter where you are
>    (Use the fully qualified names, e.g. qemu.core.qmp.QMPMessage).
>    Regressions in scripts are caught *much* faster.
>
>    Downsides: Kind of annoying; most scripts now require you to install a
>    devkit forwarder (pip3 install --user .) or be inside of an activated
>    venv. Not too bad if you know python at all, but it's certainly less
>    plug-n-play.
>
> - What's our backwards compatibility policy if we start shipping this?
>
>    Proposed: Attempt to maintain API compatibility (after stabilizing the
>    library). Incompatible changes should probably cause a semver bump.
>
>    Each published release makes no attempt to support any version of QEMU
>    other than the one it was released against. We publish this on the tin
>    in big red letters.
>
> TESTING THIS PACKAGE OUT:
>
> 1. You can install to your local user's environment normally by
> navigating to qemu/python/ and typing "pip3 install --user ."
>
> 2. If you are in a VENV, use "pip install ."
>
> 3. To install in development mode (Where the installed package always
> reflects the most recent version of the files automatically), use "pip3
> install -e ." or "pip install -e ." as appropriate (See above)
>
> John Snow (7):
>    python/qemu: create qemu.lib module
>    python/qemu: formalize as package
>    python/qemu: add README.rst
>    python/qemu: Add pipenv support
>    python/qemu: add pylint to pipenv
>    python/qemu: Add flake8 to pipenv
>    python/qemu: add mypy to pipenv
>
>   python/README.rst                         |   6 +
>   python/qemu/README.rst                    |   8 +
>   python/Pipfile                            |  14 ++
>   python/Pipfile.lock                       | 195 ++++++++++++++++++++++
>   python/qemu/__init__.py                   |  11 --
>   python/qemu/{ => core}/.flake8            |   0
>   python/qemu/core/__init__.py              |  57 +++++++
>   python/qemu/{ => core}/accel.py           |   0
>   python/qemu/{ => core}/machine.py         |   0
>   python/qemu/{ => core}/pylintrc           |   0
>   python/qemu/{ => core}/qmp.py             |   0
>   python/qemu/{ => core}/qtest.py           |   0
>   python/setup.py                           |  50 ++++++
>   scripts/device-crash-test                 |   2 +-
>   scripts/qmp/qemu-ga-client                |   2 +-
>   scripts/qmp/qmp                           |   2 +-
>   scripts/qmp/qmp-shell                     |   2 +-
>   scripts/qmp/qom-fuse                      |   2 +-
>   scripts/qmp/qom-get                       |   2 +-
>   scripts/qmp/qom-list                      |   2 +-
>   scripts/qmp/qom-set                       |   2 +-
>   scripts/qmp/qom-tree                      |   2 +-
>   scripts/render_block_graph.py             |   6 +-
>   scripts/simplebench/bench_block_job.py    |   4 +-
>   tests/acceptance/avocado_qemu/__init__.py |   2 +-
>   tests/acceptance/boot_linux.py            |   3 +-
>   tests/acceptance/virtio_check_params.py   |   2 +-
>   tests/acceptance/virtio_version.py        |   2 +-
>   tests/migration/guestperf/engine.py       |   2 +-
>   tests/qemu-iotests/235                    |   2 +-
>   tests/qemu-iotests/297                    |   2 +-
>   tests/qemu-iotests/iotests.py             |   4 +-
>   tests/vm/basevm.py                        |   6 +-
>   33 files changed, 355 insertions(+), 39 deletions(-)
>   create mode 100644 python/README.rst
>   create mode 100644 python/qemu/README.rst
>   create mode 100644 python/Pipfile
>   create mode 100644 python/Pipfile.lock
>   delete mode 100644 python/qemu/__init__.py
>   rename python/qemu/{ => core}/.flake8 (100%)
>   create mode 100644 python/qemu/core/__init__.py
>   rename python/qemu/{ => core}/accel.py (100%)
>   rename python/qemu/{ => core}/machine.py (100%)
>   rename python/qemu/{ => core}/pylintrc (100%)
>   rename python/qemu/{ => core}/qmp.py (100%)
>   rename python/qemu/{ => core}/qtest.py (100%)
>   create mode 100755 python/setup.py


--
Best regards,
Vladimir