Moto server hangs with the latest version of werkzeug (v2.2.1)

Here is what I do:

mamba env create -n test-moto  # this creates a clean environment.
conda activate test-moto
pip install moto  # OR mamba install moto -c conda-forge
moto_server -p 5555

then in a different terminal I run

curl "http://localhost:5555/"

Expected behavior: The curl should immediately return a result.

Actual behavior: The moto_server hangs. The process is at 100% CPU usage so maybe it is busy waiting for something (just a guess).

If werkzeug is manually downgraded to v2.1.0 (pip install Werkzeug=2.1.0) or previous everything works as expected.

Here is my complete pip freeze:

-- edit by @bblommers - removed to clean the thread a bit

[bblommers]

The breakage of werkzeug was a combination of things - werkzeug introduced some bugs, and also exposed some bugs in Moto. The upcoming werkzeug==2.2.2 release should at least stop Moto from hanging, but will still throw 404’s for some calls to Moto.

For now, Moto has pinned the werkzeug-dependency to < 2.2.x until we have time to resolve this completely.

As a debugging note: Some of Moto’s issues can be solved by setting the attribute RegexConverter.part_isolating = False. This will also cause other services to fail, as we only want this attribute for specific services - so we need to find a way to make this service-specific.

[bblommers]

There’s no date planned @jakirkham, but somewhere this week. I’d like to wait until we get some positive feedback that the dev-version works as expected… (hint, hint) 🙂