Advanced applications

Here are more recommendatations and suggestion that may be useful as your application grows in capability and complexity.

Project structure

A more comprehensive folder structure for advanced applications:

advanced_example_app/
├── README.md
├── src/
│   ├── .config/
│   │   ├── config_a.json
│   │   └── config_b.json
│   ├── app/
│   │   ├── __init__.py
│   │   ├── module_a.py
│   │   └── module_b.py
│   ├── packages/
│   │   └── private_package.whl
│   ├── run.py
│   └── requirements.txt
└── tests/

Divide application into smaller sub-modules

In larger applications, it may be useful to divide the application into several sub-modules. It is good practice to keep such sub-modules in an importable ‘app’ module. Import these modules in your run.py file, and execute each sub-module from there.

Separate the configuration from the code

It is good practice to separate the application code and the configuration parameters. This ensures overview and easy altering of the configuration.

One way to store configuration parameters, is to keep them in JSON files and read these files in the application code. These files may be stored in a folder under src, e.g. src/.config/config_a.json as suggested above.

Another way of storing configuration parameters, is to define them as environmental variables, i.e. configure as Variables in EngineRoom. Especially, secret parameters that you do not want to expose to others. Secrets such as passwords and “connection strings” shall never be stored together with the application code!

Note that these are just two examples of how to store configuration, but there may be other ways that fit your purpose better.

Include private packages as wheel files

Sometimes your application requires Python packages that are not available through PyPI or any other repository accesible with pip. Such packages can be included in the application as pip-installable wheel files. Remember to add these packages to the requirements.txt file, e.g.:

-f ./packages
private_package

Test your application

To validate that the application works as expected, it is important to write unit tests and integration tests for your application. Test files should be stored in the tests/ folder. It is good practice to separate the test files from the application source code.