store fails over valid yaml

[John Lenton]

I tried to push a snap with a valid snap.yaml (that snapd has no issues with),

https://pastebin.ubuntu.com/p/msD9tzpGmN/

but the store fails to read, or perhaps parse it (silently, see lp:1776302).

[Bret Barker (noise)]

See sentry issue #5276

[John Lenton (chipaca)]

Parsing that yaml with python-yaml as found in 14.04 I get that exact same error.
In 16.04 it works fine.

If I build python-yaml 3.11 from xenial in trusty, it works.

[William Grant (wgrant)]

Traceback (most recent call last):
  File "<stdin>", line 38, in <module>
  File "/usr/lib/python2.7/dist-packages/yaml/__init__.py", line 93, in safe_load
    return load(stream, SafeLoader)
  File "/usr/lib/python2.7/dist-packages/yaml/__init__.py", line 69, in load
    loader = Loader(stream)
  File "/usr/lib/python2.7/dist-packages/yaml/loader.py", line 24, in __init__
    Reader.__init__(self, stream)
  File "/usr/lib/python2.7/dist-packages/yaml/reader.py", line 79, in __init__
    self.determine_encoding()
  File "/usr/lib/python2.7/dist-packages/yaml/reader.py", line 135, in determine_encoding
    self.update(1)
  File "/usr/lib/python2.7/dist-packages/yaml/reader.py", line 169, in update
    self.check_printable(data)
  File "/usr/lib/python2.7/dist-packages/yaml/reader.py", line 144, in check_printable
    'unicode', "special characters are not allowed")
yaml.reader.ReaderError: unacceptable character #x1d42e: special characters are not allowed
  in "<string>", position 133

[William Grant (wgrant)]

Fixed by upgrading dashboard.snapcraft.io from trusty to xenial.

[Daniel Manrique (roadmr)]

This has resurfaced. Pyyaml wasn't mentioned explicitly before, but was pinned to 3.13 in sca r5194; as for the dependencies branch, a python3 build of pyyaml from source was added in r29, and the python2 build of the same, way back in r22 (I presume r22, dating from 2018-08-14, is when this regressed, although date of the previous comment contradicts this). Prior to this, it's likely we were using the system wheel which is what would have made the Xenial upgrade fix things back in the day.

I checked and pyyaml 5.1, released on 2019-03-13, fixes this when installing from wheel, so perhaps we can kill this issue for good by upgrading to that.