CloudWatch events - Fixes #52

kappa/context.py

@@ -26,6 +26,7 @@
 import kappa.event_source.kinesis
 import kappa.event_source.s3
 import kappa.event_source.sns
+import kappa.event_source.cloudwatch
 import kappa.policy
 import kappa.role
 import kappa.awsclient
@@ -181,6 +182,7 @@ def _create_event_sources(self):
             'kinesis': kappa.event_source.kinesis.KinesisEventSource,
             's3': kappa.event_source.s3.S3EventSource,
             'sns': kappa.event_source.sns.SNSEventSource,
+            'events': kappa.event_source.cloudwatch.CloudWatchEventSource
         }
         for event_source_cfg in event_sources:
             _, _, svc, _ = event_source_cfg['arn'].split(':', 3)
@@ -226,7 +228,7 @@ def create(self):
         # There is a consistency problem here.
         # If you don't wait for a bit, the function.create call
         # will fail because the policy has not been attached to the role.
-        LOG.debug('Waiting for policy/role propogation')
+        LOG.debug('Waiting for policy/role propagation')
         time.sleep(5)
         self.function.create()
         self.add_event_sources()
@@ -239,6 +241,7 @@ def deploy(self):
         self.function.deploy()
         if self.restapi:
             self.restapi.deploy()
+        self.add_event_sources()
 
     def invoke(self, data):
         return self.function.invoke(data)

kappa/event_source/cloudwatch.py

@@ -0,0 +1,113 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2014, 2015 Mitch Garnaat
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import kappa.event_source.base
+import logging
+import uuid
+
+LOG = logging.getLogger(__name__)
+
+
+class CloudWatchEventSource(kappa.event_source.base.EventSource):
+
+    def __init__(self, context, config):
+        super(CloudWatchEventSource, self).__init__(context, config)
+        self._events = kappa.awsclient.create_client('events', context.session)
+        self._lambda = kappa.awsclient.create_client('lambda', context.session)
+        self._name = config['arn'].split('/')[-1]
+        self._context = context
+        self._config = config
+
+    def get_rule(self):
+        response = self._events.call('list_rules', NamePrefix=self._name)
+        LOG.debug(response)
+        if 'Rules' in response:
+            for r in response['Rules']:
+                if r['Name'] == self._name:
+                    return r
+        return None
+
+    def add(self, function):
+        kwargs = {
+            'Name': self._name,
+            'State': 'ENABLED' if self.enabled else 'DISABLED'
+        }
+        if 'schedule' in self._config:
+            kwargs['ScheduleExpression'] = self._config['schedule']
+        if 'pattern' in self._config:
+            kwargs['EventPattern'] = self._config['pattern']
+        if 'description' in self._config:
+            kwargs['Description'] = self._config['description']
+        if 'role_arn' in self._config:
+            kwargs['RoleArn'] = self._config['role_arn']
+        try:
+            response = self._events.call('put_rule', **kwargs)
+            LOG.debug(response)
+            self._config['arn'] = response['RuleArn']
+            response = self._lambda.call('add_permission',
+                                         FunctionName=function.name,
+                                         StatementId=str(uuid.uuid4()),
+                                         Action='lambda:InvokeFunction',
+                                         Principal='events.amazonaws.com',
+                                         SourceArn=response['RuleArn'])
+            LOG.debug(response)
+            response = self._events.call('put_targets',
+                                         Rule=self._name,
+                                         Targets=[{
+                                             'Id': function.name,
+                                             'Arn': function.arn
+                                         }])
+            LOG.debug(response)
+        except Exception:
+            LOG.exception('Unable to put CloudWatch event source')
+
+    def update(self, function):
+        self.add(function)
+
+    def remove(self, function):
+        LOG.debug('removing CloudWatch event source')
+        try:
+            rule = self.get_rule()
+            if rule:
+                response = self._events.call('remove_targets',
+                                             Rule=self._name,
+                                             Ids=[function.name])
+                LOG.debug(response)
+                response = self._events.call('delete_rule',
+                                             Name=self._name)
+                LOG.debug(response)
+        except Exception:
+            LOG.exception('Unable to remove CloudWatch event source %s', self._name)
+
+    def status(self, function):
+        LOG.debug('status for CloudWatch event for %s', function.name)
+        return self._to_status(self.get_rule())
+
+    def enable(self, function):
+        if self.get_rule():
+            self._events.call('enable_rule', Name=self._name)
+
+    def disable(self, function):
+        if self.get_rule():
+            self._events.call('disable_rule', Name=self._name)
+
+    def _to_status(self, rule):
+        if rule:
+            return {
+                'EventSourceArn': rule['Arn'],
+                'State': rule['State']
+            }
+        else:
+            return None

samples/cron/.gitignore

@@ -0,0 +1,4 @@
+.kappa/
+kappa.yml
+*.zip
+

samples/cron/_src/simple.py

@@ -0,0 +1,10 @@
+import logging
+import time
+
+LOG = logging.getLogger()
+LOG.setLevel(logging.DEBUG)
+
+
+def handler(event, context):
+    LOG.debug(event)
+    return {'status': 'success', 'time': time.time()}

samples/cron/_tests/test_one.json

@@ -0,0 +1,4 @@
+{
+    "foo": "bar",
+    "fie": "baz"
+}

samples/cron/kappa.yml.sample

@@ -0,0 +1,23 @@
+---
+name: kappa-cron
+environments:
+  dev:
+    profile: <your profile here>
+    region: <your region here>
+    policy:
+      resources:
+        - arn: arn:aws:logs:*:*:*
+          actions:
+          - "*"
+    event_sources:
+      - arn: arn:aws:events:<your region here>:<your account id>:rule/kappa-cron-dev
+        schedule: rate(1 minute)
+        description: cron to run this lambda function every minute
+        enabled: true
+lambda:    
+  description: Kappa sample lambda that runs every minute
+  handler: simple.handler
+  runtime: python2.7
+  memory_size: 128
+  timeout: 3
+