Merge pull request #268 from jsocol/add-system-check

add system check

django_ratelimit/apps.py

@@ -0,0 +1,10 @@
+from django.apps import AppConfig
+
+
+class DjangoRatelimitConfig(AppConfig):
+    name = 'django_ratelimit'
+    label = 'ratelimit'
+    default = True
+
+    def ready(self):
+        from . import checks  # noqa: F401

django_ratelimit/checks.py

@@ -0,0 +1,69 @@
+from django.conf import settings
+from django.core import checks
+
+SUPPORTED_CACHE_BACKENDS = [
+    'django.core.cache.backends.memcached.PyMemcacheCache',
+    'django.core.cache.backends.memcached.PyLibMCCache',
+    'django_redis.cache.RedisCache',
+]
+
+CACHE_FAKE = 'is not a real cache'
+CACHE_NOT_SHARED = 'is not a shared cache'
+CACHE_NOT_ATOMIC = 'does not support atomic increment'
+
+KNOWN_BROKEN_CACHE_BACKENDS = {
+    'django.core.cache.backends.dummy.DummyCache': CACHE_FAKE,
+    'django.core.cache.backends.locmem.LocMemCache': CACHE_NOT_SHARED,
+    'django.core.cache.backends.filebased.FileBasedCache': CACHE_NOT_ATOMIC,
+    'django.core.cache.backends.db.DatabaseCache': CACHE_NOT_ATOMIC,
+}
+
+
+@checks.register(checks.Tags.caches, 'django_ratelimit')
+def check_caches(app_configs, **kwargs):
+    errors = []
+    cache_name = getattr(settings, 'RATELIMIT_USE_CACHE', 'default')
+    caches = getattr(settings, 'CACHES', None)
+    if caches is None:
+        errors.append(
+            checks.Error(
+                'CACHES is not defined, django_ratelimit will not work',
+                hint='Configure a default cache using memcached or redis.',
+                id='django_ratelimit.E001',
+            )
+        )
+        return errors
+
+    if cache_name not in caches:
+        errors.append(
+            checks.Error(
+                f'RATELIMIT_USE_CACHE value "{cache_name}"" does not '
+                f'appear in CACHES dictionary',
+                hint='RATELIMIT_USE_CACHE must be set to a valid cache',
+                id='django_ratelimit.E002',
+            )
+        )
+        return errors
+
+    cache_config = caches[cache_name]
+    backend = cache_config['BACKEND']
+
+    reason = KNOWN_BROKEN_CACHE_BACKENDS.get(backend, None)
+    if reason is not None:
+        errors.append(
+            checks.Error(
+                f'cache backend {backend} {reason}',
+                hint='Use a supported cache backend',
+                id='django_ratelimit.E003',
+            )
+        )
+
+    if backend not in SUPPORTED_CACHE_BACKENDS:
+        errors.append(
+            checks.Warning(
+                f'cache backend {backend} is not officially supported',
+                id='django_ratelimit.W001',
+            )
+        )
+
+    return errors

django_ratelimit/core.py

@@ -240,7 +240,6 @@ def get_usage(request, group=None, fn=None, key=None, rate=None, method=ALL,
         else:
             count = cache.get(cache_key, initial_value)
 
-    print(f'The count is {count}')
     # Getting or setting the count from the cache failed
     if count is None or count is False:
         if getattr(settings, 'RATELIMIT_FAIL_OPEN', False):

test_settings.py

@@ -1,5 +1,7 @@
 SECRET_KEY = 'ratelimit'
 
+SILENCED_SYSTEM_CHECKS = ['django_ratelimit.E003', 'django_ratelimit.W001']
+
 INSTALLED_APPS = (
     'django_ratelimit',
 )