Zip file created with a default (file) mode causes corrupted Azure function

[romanofski]

Disclaimer: I'm not sure whether this is a bug in rules_pkg or really a problem in Azure. However I thought I better file it regardless in case others stumble over this since the "workaround" is easy. So feel free to close.

We're using the packaging rules to package up Azure Function Apps. The mode used to create a zipfile.ZipInfo object in the zip file created, causes a broken Azure Function App deployment. The main problem seems to be the file mode which differs significantly when used zipfile.ZipInfo.from_file:

Env details

OS: GNU/Linux - Ubuntu 22.04 running in WSL2
Python: 3.11.0

Problem description

The filemode set with the current code:

> <ZipInfo filename='dist/main.js' filemode='?rw-r--r--' file_size=3408 compress_size=0>
> entry_info.external_attr
27525120
> oct(entry_info.external_attr >> 16)
'0o644'

The filemode when the info is constructed with zipfile.ZipInfo.from_file:

> <ZipInfo filename='dist/main.js' filemode='-rw-r--r--' file_size=3408 compress_size=0>
> oct(info.external_attr >> 16)
'0o100644'

You'll notice the ? at the beginning of the zipinfo for the file if constructed with the current default mode.

Reproducer

I can reproduce this 100% with access to deploying a function app. I see if I can file a bug somewhere in Azure too. A minimal reproducer is to create a zip file with the make_zipinfo method from build_zip.py using a 16bit? file mode (0o644).

Workaround

The workaround I currently use is to set an explicit file mode:

pkg_files(
    name = "pkg_zip_contents",
    srcs = [
        ":zip_contents",
    ],
    strip_prefix = strip_prefix.from_pkg(),
    attributes = pkg_attributes(
        mode = '100644',
    ),
)

It seems using a 32bit file mode (sorry only stumbled over it in a Stackoverflow post about git file modes is not causing this confusing behaviour in deployment.

[aiuto]

It looks like we should be adding the file mode bits in addition to permissions.
That seems like an easy change to build_zip.py

[aiuto]

Please patch and try #804.
It's not clear if there needs to be a special bit for plain files on Windows too

[romanofski]

@aiuto thanks for the quick reply. I'll double check what happens on Windows.

[romanofski]

This works for me. Baseline without the patch:

>>> import zipfile
>>> foo = zipfile.ZipFile('test.zip')
>>> foo.infolist()[0]
<ZipInfo filename='.funcignore' compress_type=deflate filemode='?rw-r--r--' file_size=105 compress_size=82>

Then I used a local_override to grab the patch:

local_path_override(module_name = "rules_pkg", path = "rules_pkg")

Created the zip again and now I get the proper file attributes:

>>> foo = zipfile.ZipFile('test.zip')
>>> foo.infolist()[0]
<ZipInfo filename='.funcignore' compress_type=deflate filemode='-rw-r--r--' file_size=105 compress_size=82>