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Deployment issues on Heroku - multipage app layout

I do not have a multipage application but I am attempting to use the flat project layout from URL Routing and Multiple Apps | Dash for Python Documentation | Plotly so that I can have callbacks in a separate module. To deploy this layout to Heroku I believe I need

web: gunicorn index:server

in my procfile. However, I receive the error
“”“Failed to find attribute ‘server’ in ‘index’”""
My code base is GitHub - thomasmatt88/NCAMP-dashboard: NCAMP, the National Center for Advanced Materials Performance, works with the FAA and industry partners to qualify material systems and populate a shared materials database that can be viewed publicly. This is a dashboard for viewing NCAMP materials database. where you can see I’ve attempted many deployment tests in my recent commits.

Notably, I have this block of code in my app.py file

app = dash.Dash(__name__, external_stylesheets=[dbc.themes.BOOTSTRAP])
server = app.server #need to add this line for heroku deployment
server.secret_key = os.environ.get('secret_key', 'secret')
app.config.suppress_callback_exceptions = True

And this block of code in my index.py file

if __name__ == '__main__':
    #don't use debug = True on production server
    app.run_server(debug=True)

Problem solved by following this stack overflow answer

There’s a good solution here too.