Support disabling the pkl cache for sandboxed/hermetic builds

[mexlez12345]

Looks like by default the codegen tries to use the "global" pkl cache at ~/.pkl.

This breaks builds that use strict sandboxing (ex. bazel) that disallow write access outside of the build directory.

To address this, would it be possible to support ex. --no-cache args similar to the "core" pkl CLI tools?

https://pkl-lang.org/main/current/pkl-cli/index.html#common-options

–– Pkl Error ––
I/O error loading module `package://github.com/jw-y/pkl-python/releases/download/v0.1.16/pkl.python@0.1.16#/Generator.pkl`.
FileSystemException: /home/user/.pkl: Read-only file system

1 | amends "package://github.com/jw-y/pkl-python/releases/download/v0.1.16/pkl.python@0.1.16#/Generator.pkl"
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
at tmpn_frdii6 (file:///tmp/tmpn_frdii6.pkl)

  warnings.warn(str(e))

[jw-y]

Is there a use case that i can reproduce?

[jw-y]

Not sure if it will work,
but try putting the Generator.pkl file into the build directory and pass the file path to --generator-settings flag.

The core pkl binary by default uses cache for remote files and you probably would want that too.
If it is local, it won't use the cache.

[mexlez12345]

Probably hard to reproduce :P this is a non-trivial private codebase.

We're running https://bazel.build/ which sandboxes all build steps (ex. no access to system-wide filesystem, no network access) except for explicitly declared dependencies, so when pkl-python tries to "externally" download the pkl binary and supporting files, it gets blocked (as per error message above).

In our case bazel handles all the caching etc. for intermediates.

[jw-y]

Have you tried inserting Generator.pkl into the project before build?
If you don't have that file there is no way of generating python code anyways.