Trying to run an exe from stlite desktop app

[caleb-depotanalytics]

Hey!

Since I need pyodbc for a Desktop app that I am creating, I am using pyinstaller to create a backend app that will serve as sort of a local API hub (with just cmd line options) for my non-pure python calls.

As a result, from the stlite/desktop app, I need to run a file called "database.exe" which can be any known location on the filesystem. I tried installing it in C:\Program Files\database.exe, and the streamlit desktop app couldn't find it:

Hopefully, this image illustrates the situation well.

Could anyone point me toward the best way to solve this problem?

[whitphx]

Unfortunately, it is not possible at this point, as long as I understand the situation correctly.

It is because, in short, Streamlit apps on the @stlite/desktop runtime are not allowed to access the host file system by design, and for security reasons.

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In details, the stlite runtime is "sandboxed".
When you launch a stlite app, first Pyodide is started, then Streamlit is run on it. And Pyodide has its own virtual file system that the Python code running on Pyodide can only have access to.
Then, a Streamlit app running on stlite can only access to this virtual file system, and @stlite/desktop controls it so that only the build directory's contents are mounted to the virtual FS to be input to the stlite runtime.
So, currently there is no way for Streamlit apps running in @stlite/desktop to access anything outside the build directory .

---

There is a related issue: #463, which may require access to the host file system.
In addition to it, please create an issue as a feature request and continue the discussion on what kind of feature or API stlite should have to fulfill this need.

[caleb-depotanalytics]

Could I add the exe to the build directory as an external resource and call it from there?

[whitphx]

Probably not.

You can bundle the exe file in the build directory, which will be copied to the virtual file system and stlite can read it then. However, the binary which the stlite app can see is a copy on the virtual file system. So it is still not possible for the stlite app to access the exe file on the host file system.

[whitphx]

If launching another exe file is the purpose, launching an app with a URL scheme may work, although I haven't tried it.
https://learn.microsoft.com/en-us/windows/uwp/launch-resume/launch-default-app

As the desktop app of @stlite/desktop is a kind of web app which is running on an Electron-bundled Chrome, such web-based technique should be able to be used.

[caleb-depotanalytics]

Thanks so much for this - I actually got to the answer. If I just place my exe (database.exe) in streamlit_app directory. and called database.exe directly, likeso:

if sys.platform == "emscripten":
    db_call_exe = Path("database.exe") # Path("C:\\") / "Program Files" / "database.exe"
    if not db_call_exe.exists():
        st.write(f"database.exe not found in {str(db_call_exe)}")
        st.write(Path(".").glob("*"))
else: # sys.platform == "win32":
    db_call_exe = Path(__file__).parent.parent.parent / "database-utility" / "database.exe"

These two exes will be inseparably linked, so this is not an issue at all for me to do.

I'd be interested to try to URL scheme to, but I think this is fine for our case.

[caleb-depotanalytics]

Actually, nevermind - didn't realize I was getting some data from the cache earlier and not actually calling the .exe:

OSError: [Errno 52] Function not implemented
Traceback:
File "/lib/python3.10/site-packages/streamlit/runtime/scriptrunner/script_runner.py", line 564, in _run_script
    exec(code, module.__dict__)
File "/home/pyodide/streamlit_app.py", line 65, in <module>
    add_new_project_template()
File "/home/pyodide/streamlit_app.py", line 24, in add_new_project_template
    projects = get_all_project_types()
File "/home/pyodide/workstream/data_calls.py", line 53, in get_all_project_types
    return exec_db_call("get_all_project_types")
File "/home/pyodide/workstream/data_calls.py", line 42, in exec_db_call
    subprocess.call(call_list, stdout=sys.stdout)
File "/lib/python3.10/subprocess.py", line 345, in call
    with Popen(*popenargs, **kwargs) as p:
File "/lib/python3.10/subprocess.py", line 966, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
File "/lib/python3.10/subprocess.py", line 1775, in _execute_child
    self.pid = _posixsubprocess.fork_exec(

I guess that's just a pyodide shortcoming?

[caleb-depotanalytics]

Or in retrospect, I guess that pyodide is functionally creating a linux container in the browser... Maybe it's possible to execute linux binaries from within the app? Would I just be wasting my time trying that out or should I give it a shot?

[whitphx]

I guess that's just a pyodide shortcoming?

Yes.

I think neither Win or Linux binary works in the Pyodide environment. It provides a POSIX-like file system so the file paths look like Linux's ones, but it's not a Linux container.

[caleb-depotanalytics]

Okay, dang - thanks for all the answers on this!!