Use memcached for rate-limiting the API calls.

[plcapi.git] / aspects / ratelimitaspects.py

diff --git a/aspects/ratelimitaspects.py b/aspects/ratelimitaspects.py
new file mode 100644 (file)
index 0000000..0346567
--- /dev/null
+++ b/aspects/ratelimitaspects.py
@@ -0,0 +1,66 @@
+from PLC.Config import Config
+from PLC.Faults import *
+
+from datetime import datetime, timedelta
+from pyaspects.meta import MetaAspect
+import memcache
+
+class BaseRateLimit(object):
+
+    def __init__(self):
+        self.config = Config("/etc/planetlab/plc_config")
+
+        self.prefix = "ratelimit"
+        self.minutes = 3 # The time period
+        self.requests = 10 # Number of allowed requests in that time period
+        self.expire_after = (self.minutes + 1) * 60
+
+    def before(self, wobj, data, *args, **kwargs):
+        # ratelimit_128.112.139.115_201011091532 = 1
+        # ratelimit_128.112.139.115_201011091533 = 14
+        # ratelimit_128.112.139.115_201011091534 = 11
+        # Now, on every request we work out the keys for the past five minutes and use get_multi to retrieve them. 
+        # If the sum of those counters exceeds the maximum allowed for that time period, we block the request.
+
+        api_method_name = wobj.name
+        api_method_source = wobj.source
+
+        if api_method_source == None or api_method_source[0] == self.config.PLC_API_HOST:
+            return
+
+        mc = memcache.Client(['%s:11211'] % self.config.PLC_API_HOST)
+        now = datetime.now()
+        current_key = '%s_%s_%s' % (self.prefix, api_method_source[0], now.strftime('%Y%m%d%H%M'))
+
+        keys_to_check = ['%s_%s_%s' % (self.prefix, api_method_source[0], (now - timedelta(minutes = minute)).strftime('%Y%m%d%H%M')) for minute in range(self.minutes + 1)]
+
+        try:
+            mc.incr(current_key)
+        except ValueError:
+            mc.set(current_key, 1, time=self.expire_after)
+
+        result = mc.get_multi(keys_to_check)
+        total_requests = 0
+        for i in result:
+            total_requests += result[i]
+
+        if total_requests > self.requests:
+            raise PLCPermissionDenied, "Maximum allowed number of API calls exceeded"
+
+    def after(self, wobj, data, *args, **kwargs):
+        return
+
+class RateLimitAspect_class(BaseRateLimit):
+    __metaclass__ = MetaAspect
+    name = "ratelimitaspect_class"
+
+    def __init__(self):
+        BaseRateLimit.__init__(self)
+
+    def before(self, wobj, data, *args, **kwargs):
+        BaseRateLimit.before(self, wobj, data, *args, **kwargs)
+
+    def after(self, wobj, data, *args, **kwargs):
+        BaseRateLimit.after(self, wobj, data, *args, **kwargs)
+
+RateLimitAspect = RateLimitAspect_class