Re: [PATCH v4 14/35] tests/functional: add a module for handling asset download & caching

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Aug 21, 2024 at 04:49:42PM +0200, Philippe Mathieu-Daudé wrote:
> On 21/8/24 10:27, Thomas Huth wrote:
> > From: Daniel P. Berrangé <berrange@redhat.com>
> > 
> > The 'Asset' class is a simple module that declares a downloadable
> > asset that can be cached locally. Downloads are stored in the user's
> > home dir at ~/.cache/qemu/download, using a sha256 sum of the URL.
> > 
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > [thuth: Drop sha1 support, use hash on file content for naming instead of URL,
> >          add the possibility to specify the cache dir via environment variable]
> > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > ---
> >   tests/functional/qemu_test/__init__.py |  1 +
> >   tests/functional/qemu_test/asset.py    | 97 ++++++++++++++++++++++++++
> >   2 files changed, 98 insertions(+)
> >   create mode 100644 tests/functional/qemu_test/asset.py
> > 
> > diff --git a/tests/functional/qemu_test/__init__.py b/tests/functional/qemu_test/__init__.py
> > index 2f1e0bc70d..db05c8f412 100644
> > --- a/tests/functional/qemu_test/__init__.py
> > +++ b/tests/functional/qemu_test/__init__.py
> > @@ -6,6 +6,7 @@
> >   # later.  See the COPYING file in the top-level directory.
> > +from .asset import Asset
> >   from .config import BUILD_DIR
> >   from .cmd import has_cmd, has_cmds, run_cmd, is_readable_executable_file, \
> >       interrupt_interactive_console_until_pattern, wait_for_console_pattern, \
> > diff --git a/tests/functional/qemu_test/asset.py b/tests/functional/qemu_test/asset.py
> > new file mode 100644
> > index 0000000000..cbeb6278af
> > --- /dev/null
> > +++ b/tests/functional/qemu_test/asset.py
> > @@ -0,0 +1,97 @@
> > +# Test utilities for fetching & caching assets
> > +#
> > +# Copyright 2024 Red Hat, Inc.
> > +#
> > +# This work is licensed under the terms of the GNU GPL, version 2 or
> > +# later.  See the COPYING file in the top-level directory.
> > +
> > +import hashlib
> > +import logging
> > +import os
> > +import subprocess
> > +import urllib.request
> > +from pathlib import Path
> > +from shutil import copyfileobj
> > +
> > +
> > +# Instances of this class must be declared as class level variables
> > +# starting with a name "ASSET_". This enables the pre-caching logic
> > +# to easily find all referenced assets and download them prior to
> > +# execution of the tests.
> > +class Asset:
> > +
> > +    def __init__(self, url, hashsum):
> > +        self.url = url
> > +        self.hash = hashsum
> > +        cache_dir_env = os.getenv('QEMU_TEST_CACHE_DIR')
> > +        if cache_dir_env:
> > +            self.cache_dir = Path(cache_dir_env, "download")
> > +        else:
> > +            self.cache_dir = Path(Path("~").expanduser(),
> > +                                  ".cache", "qemu", "download")
> > +        self.cache_file = Path(self.cache_dir, hashsum)
> > +        self.log = logging.getLogger('qemu-test')
> > +
> > +    def __repr__(self):
> > +        return "Asset: url=%s hash=%s cache=%s" % (
> > +            self.url, self.hash, self.cache_file)
> > +
> > +    def _check(self, cache_file):
> > +        if self.hash is None:
> > +            return True
> > +        if len(self.hash) == 64:
> > +            sum_prog = 'sha256sum'
> > +        elif len(self.hash) == 128:
> > +            sum_prog = 'sha512sum'
> > +        else:
> > +            raise Exception("unknown hash type")
> > +
> > +        checksum = subprocess.check_output(
> > +            [sum_prog, str(cache_file)]).split()[0]
> > +        return self.hash == checksum.decode("utf-8")
> > +
> > +    def valid(self):
> > +        return self.cache_file.exists() and self._check(self.cache_file)
> > +
> > +    def fetch(self):
> > +        if not self.cache_dir.exists():
> > +            self.cache_dir.mkdir(parents=True, exist_ok=True)
> 
> This doesn't work with QEMU_TEST_CACHE_DIR set to someone else:
> 
>   File
> "/home/philippe.mathieu-daude/qemu/tests/functional/qemu_test/asset.py",
> line 60, in fetch
>     self.cache_dir.mkdir(parents=True, exist_ok=True)
>   File "/usr/lib/python3.10/pathlib.py", line 1175, in mkdir
>     self._accessor.mkdir(self, mode)
> PermissionError: [Errno 13] Permission denied:
> '/home/alex.bennee/.cache/qemu/download'
> ninja: build stopped: subcommand failed.
> 
> Maybe use a getter which falls back to Path("~").expanduser() when
> no access on QEMU_TEST_CACHE_DIR? This happens when downloading a
> new file (the recent MIPS tests I converted) which isn't in Alex's cache:

Is it really valid to point QEMU_TEST_CACHE_DIR to a directory
that you don't have permission to access ? This feels like it
could be classed as invalid usage to me, rather than needing a
workaround.

> 
> 2024-08-21 15:45:48,896 - qemu-test - INFO - Attempting to cache 'Asset: url=https://s3-eu-west-1.amazonaws.com/downloads-mips/mips-downloads/YAMON/yamon-bin-02.22.zip
> hash=eef86f0eed0ef554f041dcd47b87eebea0e6f9f1184ed31f7e9e8b4a803860ab cache=/home/alex.bennee/.cache/download/eef86f0eed0ef554f041dcd47b87eebea0e6f9f1184ed31f7e9e8b4a803860ab'
> 
> > +        if self.valid():
> > +            self.log.debug("Using cached asset %s for %s",
> > +                           self.cache_file, self.url)
> > +            return str(self.cache_file)
> > +
> > +        self.log.info("Downloading %s to %s...", self.url, self.cache_file)
> > +        tmp_cache_file = self.cache_file.with_suffix(".download")
> > +
> > +        try:
> > +            resp = urllib.request.urlopen(self.url)
> > +        except Exception as e:
> > +            self.log.error("Unable to download %s: %s", self.url, e)
> > +            raise
> > +
> > +        try:
> > +            with tmp_cache_file.open("wb+") as dst:
> > +                copyfileobj(resp, dst)
> > +        except:
> > +            tmp_cache_file.unlink()
> > +            raise
> > +        try:
> > +            # Set these just for informational purposes
> > +            os.setxattr(str(tmp_cache_file), "user.qemu-asset-url",
> > +                        self.url.encode('utf8'))
> > +            os.setxattr(str(tmp_cache_file), "user.qemu-asset-hash",
> > +                        self.hash.encode('utf8'))
> > +        except Exception as e:
> > +            self.log.info("Unable to set xattr on %s: %s", tmp_cache_file, e)
> > +            pass
> > +
> > +        if not self._check(tmp_cache_file):
> > +            tmp_cache_file.unlink()
> > +            raise Exception("Hash of %s does not match %s" %
> > +                            (self.url, self.hash))
> > +        tmp_cache_file.replace(self.cache_file)
> > +
> > +        self.log.info("Cached %s at %s" % (self.url, self.cache_file))
> > +        return str(self.cache_file)
> 

With regards,
Daniel
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