prepare_docker does not work with a local pin board

[rundel]

Describe the bug
The Dockerfile and app.py do not include the board folder contents either by copying or by use of a volume which then causes a failure on runtime.

To Reproduce
Steps to reproduce the behavior:

1. Run the sample code provided with prepare_docker documentation
2. Navigate to tmp.name
3. Run docker build . -t test
4. Run docker run -p 8080:8080 test
5. The following error occurs:

Traceback (most recent call last):
  File "/usr/local/bin/uvicorn", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/usr/local/lib/python3.12/site-packages/click/core.py", line 1161, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/click/core.py", line 1082, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/click/core.py", line 1443, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/click/core.py", line 788, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/uvicorn/main.py", line 412, in main
    run(
  File "/usr/local/lib/python3.12/site-packages/uvicorn/main.py", line 579, in run
    server.run()
  File "/usr/local/lib/python3.12/site-packages/uvicorn/server.py", line 66, in run
    return asyncio.run(self.serve(sockets=sockets))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/asyncio/runners.py", line 195, in run
    return runner.run(main)
           ^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/asyncio/base_events.py", line 691, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/uvicorn/server.py", line 70, in serve
    await self._serve(sockets)
  File "/usr/local/lib/python3.12/site-packages/uvicorn/server.py", line 77, in _serve
    config.load()
  File "/usr/local/lib/python3.12/site-packages/uvicorn/config.py", line 435, in load
    self.loaded_app = import_from_string(self.app)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/uvicorn/importer.py", line 19, in import_from_string
    module = importlib.import_module(module_str)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/importlib/__init__.py", line 90, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1387, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 999, in exec_module
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "/vetiver/app/app.py", line 9, in <module>
    v = VetiverModel.from_pin(b, 'my_model', version = '20250331T104040Z-e0705')
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/vetiver/vetiver_model.py", line 110, in from_pin
    model = board.pin_read(name, version)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/pins/boards.py", line 203, in pin_read
    meta = self.pin_fetch(name, version)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/pins/boards.py", line 178, in pin_fetch
    meta = self.pin_meta(name, version)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/pins/boards.py", line 135, in pin_meta
    raise PinsError(
pins.errors.PinsError: Pin my_model either does not exist, or is missing version: 20250331T104040Z-e0705.

Expected behavior
The docker image is able to run the model api without additional intervention.

[juliasilge]

This actually is by design! We have some discussion on this in:

• Dockerfile does not work out of the box (port not exposed, no access to the board) vetiver-r#101
• vetiver_write_docker with local pins should it add the folder to the docker container? vetiver-r#155
• Handle folder pin boards in vetiver_write_docker() vetiver-r#211

We also have covered this in talks, such as in this talk by @isabelizimm from 2022, and we have this documented at https://vetiver.posit.co/learn-more/deploy-with-docker.html#version-your-model.

If you do want to experiment with mounting the model inside the Docker container, I have a version of this for R in https://gist.github.com/juliasilge/b4c04c80eed1481454e273be833ae3e1 and you could take the same approach for Python. However, be aware that we do consider this an "off-label" use.

[rundel]

Thanks for the context - it is helpful to get a better idea about the design ideas behind this.

I completely missed that info box when I was working my way through the documentation this semester and would advocate for making that a full subsection of the documentation so it is easier to see. It would also be helpful to have an included example using -v to mount a local pin board as so much of the rest of the documentation and the getting started materials use those as an example.

One other thought, and this is driven by my particular use case of teaching MS students, is that while I get the reasoning around not including the pin board in the Dockerfile I still think there is a case to be made around having the ability to include a single model. This would let you version your images to specific models which seems reasonable and allow the image to not have to rely on a volume, s3 bucket, or connect instance.