Add a section for settings

README.md

@@ -37,6 +37,9 @@ Django styleguide that we use in [HackSoft](https://hacksoft.io).
   * [Nested serializers](#nested-serializers)
   * [Advanced serialization](#advanced-serialization)
 - [Urls](#urls)
+- [Settings](#settings)
+  * [Integrations](#integrations)
+  * [Reading from `.env`](#reading-from-env)
 - [Errors & Exception Handling](#errors--exception-handling)
   * [How exception handling works (in the context of DRF)](#how-exception-handling-works-in-the-context-of-drf)
     + [DRF's `ValidationError`](#drfs-validationerror)
@@ -1019,6 +1022,128 @@ urlpatterns = [
 
 **Splitting urls like that can give you the extra flexibility to move separate domain patterns to separate modules**, especially for really big projects, where you'll often have merge conflicts in `urls.py`.
 
+## Settings
+
+When it comes to Django settings, we tend to follow the folder structure from [`cookiecutter-django`](https://github.com/cookiecutter/cookiecutter-django), with few adjustments:
+
+- We separate Django specific settings from other settings.
+- Everything should be included in `base.py`.
+    - There should be nothing that's only included in `production.py`.
+    - Things that need to only work in production are controlled via environment variables.
+
+Here's the folder structure of our [`Styleguide-Example`](https://github.com/HackSoftware/Styleguide-Example) project:
+
+```
+config
+├── __init__.py
+├── django
+│   ├── __init__.py
+│   ├── base.py
+│   ├── local.py
+│   ├── production.py
+│   └── test.py
+├── settings
+│   ├── __init__.py
+│   ├── celery.py
+│   ├── cors.py
+│   ├── sentry.py
+│   └── sessions.py
+├── urls.py
+├── env.py
+└── wsgi.py
+├── asgi.py
+```
+
+In `config/django`, we put everything that's Django related:
+
+- `base.py` contains most of the settings & imports everything else from `config/settings`
+- `production.py` imports from `base.py` and then overwrites some specific settings for production.
+- `test.py` imports from `base.py` and then overwrites some specific settings for running tests.
+    - This should be used as the settings module in `pytest.ini`.
+- `local.py` imports from `base.py` and can overwrite some specific settings for local development.
+    - If you want to use that, point to `local` in `manage.py`. Otherwise stick with `base.py`
+
+In `config/settings`, we put everything else:
+
+- Celery configuration.
+- 3rd party configurations.
+- etc.
+
+This gives you a nice separation of modules.
+
+Additionally, we usually have `config/env.py` with the following code:
+
+```python
+import environ
+
+env = environ.Env()
+```
+
+And then, whenever we need to read something from the environment, we import like that:
+
+```python
+from config.env import env
+```
+
+Usually, at the end of the `base.py` module, we import everything from `config/settings`:
+
+```python
+from config.settings.cors import *  # noqa
+from config.settings.sessions import *  # noqa
+from config.settings.celery import *  # noqa
+from config.settings.sentry import *  # noqa
+```
+
+### Integrations
+
+Since everything should be imported in `base.py`, but sometimes we don't want to configure a certain integration for local development, we derived the following approach:
+
+- Integration-specific settings are placed in `config/settings/some_integration.py`
+- There's always a boolean setting called `USE_SOME_INTEGRATION`, which reads from the environment & defaults to `False`.
+- If the value is `True`, then proceed reading other settings & failing if things are not present in the environment.
+
+For example, lets take a look at `config/settings/sentry.py`:
+
+```python
+from config.env import env
+
+SENTRY_DSN = env('SENTRY_DSN', default='')
+
+if SENTRY_DSN:
+    import sentry_sdk
+    from sentry_sdk.integrations.django import DjangoIntegration
+    from sentry_sdk.integrations.celery import CeleryIntegration
+
+    # ... we proceed with sentry settings here ...
+    # View the full file here - 
+```
+
+### Reading from `.env`
+
+Having a local `.env` is a nice way of providing values for your settings.
+
+And the good thing is, [`django-environ`](https://django-environ.readthedocs.io/en/latest/) provides you with a way to do that:
+
+```python
+# That's in the beginning of base.py
+
+import os
+
+from config.env import env, environ
+
+# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
+BASE_DIR = environ.Path(__file__) - 3
+
+env.read_env(os.path.join(BASE_DIR, ".env"))
+```
+
+Now you can have a `.env` (but it's not required) file in your project root & place values for your settings there.
+
+There are 2 things worth mentioning here:
+
+1. Don't put `.env` in your source control, since this will leak credentials.
+2. Rather put an `.env.example` with empty values for everything, so new developers can figure out what's being used. 
+
 ## Errors & Exception Handling
 
 > 👀 If you want the code, hop to the `Styleguide-Example` project - <https://github.com/HackSoftware/Styleguide-Example/blob/master/styleguide_example/api/exception_handlers.py>