feat(api): load config using shared helpers

- add django settings module documentation
- use default for previously required fields

BREAKING CHANGE: The API command line interface require the
configuration file to be present. The default configuration file path is
`/etc/airtime/airtime.conf`

api/libretime_api/settings/_internal.py

@@ -0,0 +1,141 @@
+from os import getenv
+from typing import Optional
+
+# SECURITY WARNING: don't run with debug turned on in production!
+DEBUG = getenv("LIBRETIME_DEBUG")
+
+# Application definition
+
+INSTALLED_APPS = [
+    "libretime_api.apps.LibreTimeAPIConfig",
+    "django.contrib.auth",
+    "django.contrib.contenttypes",
+    "django.contrib.sessions",
+    "django.contrib.messages",
+    "django.contrib.staticfiles",
+    "rest_framework",
+    "django_filters",
+    "drf_spectacular",
+]
+
+MIDDLEWARE = [
+    "django.middleware.security.SecurityMiddleware",
+    "django.contrib.sessions.middleware.SessionMiddleware",
+    "django.middleware.common.CommonMiddleware",
+    "django.middleware.csrf.CsrfViewMiddleware",
+    "django.contrib.auth.middleware.AuthenticationMiddleware",
+    "django.contrib.messages.middleware.MessageMiddleware",
+    "django.middleware.clickjacking.XFrameOptionsMiddleware",
+]
+
+ROOT_URLCONF = "libretime_api.urls"
+
+TEMPLATES = [
+    {
+        "BACKEND": "django.template.backends.django.DjangoTemplates",
+        "DIRS": [],
+        "APP_DIRS": True,
+        "OPTIONS": {
+            "context_processors": [
+                "django.template.context_processors.debug",
+                "django.template.context_processors.request",
+                "django.contrib.auth.context_processors.auth",
+                "django.contrib.messages.context_processors.messages",
+            ],
+        },
+    },
+]
+
+WSGI_APPLICATION = "libretime_api.wsgi.application"
+
+# Password validation
+# https://docs.djangoproject.com/en/3.0/ref/settings/#auth-password-validators
+
+AUTH_PASSWORD_VALIDATORS = [
+    {
+        "NAME": "django.contrib.auth.password_validation.UserAttributeSimilarityValidator",
+    },
+    {
+        "NAME": "django.contrib.auth.password_validation.MinimumLengthValidator",
+    },
+    {
+        "NAME": "django.contrib.auth.password_validation.CommonPasswordValidator",
+    },
+    {
+        "NAME": "django.contrib.auth.password_validation.NumericPasswordValidator",
+    },
+]
+
+# Rest Framework settings
+# https://www.django-rest-framework.org/api-guide/settings/
+
+renderer_classes = ["rest_framework.renderers.JSONRenderer"]
+if DEBUG:
+    renderer_classes += ["rest_framework.renderers.BrowsableAPIRenderer"]
+
+REST_FRAMEWORK = {
+    "DEFAULT_RENDERER_CLASSES": renderer_classes,
+    "DEFAULT_AUTHENTICATION_CLASSES": (
+        "rest_framework.authentication.SessionAuthentication",
+        "rest_framework.authentication.BasicAuthentication",
+    ),
+    "DEFAULT_PERMISSION_CLASSES": [
+        "libretime_api.permissions.IsSystemTokenOrUser",
+    ],
+    "DEFAULT_FILTER_BACKENDS": [
+        "django_filters.rest_framework.DjangoFilterBackend",
+    ],
+    "DEFAULT_SCHEMA_CLASS": "drf_spectacular.openapi.AutoSchema",
+    "URL_FIELD_NAME": "item_url",
+}
+
+AUTH_USER_MODEL = "libretime_api.User"
+
+TEST_RUNNER = "libretime_api.tests.runners.ManagedModelTestRunner"
+
+
+# Logging
+def setup_logger(log_filepath: Optional[str]):
+    logging_handlers = {
+        "console": {
+            "level": "INFO",
+            "class": "logging.StreamHandler",
+            "formatter": "simple",
+        },
+    }
+
+    if log_filepath is not None:
+        logging_handlers["file"] = {
+            "level": "DEBUG",
+            "class": "logging.FileHandler",
+            "filename": log_filepath,
+            "formatter": "verbose",
+        }
+
+    return {
+        "version": 1,
+        "disable_existing_loggers": False,
+        "formatters": {
+            "simple": {
+                "format": "{levelname} {message}",
+                "style": "{",
+            },
+            "verbose": {
+                "format": "{asctime} {module} {levelname} {message}",
+                "style": "{",
+            },
+        },
+        "handlers": logging_handlers,
+        "loggers": {
+            "django": {
+                "handlers": logging_handlers.keys(),
+                "level": "INFO",
+                "propagate": True,
+            },
+            "libretime_api": {
+                "handlers": logging_handlers.keys(),
+                "level": "INFO",
+                "propagate": True,
+            },
+        },
+    }