Add module for managing CloudWatch Event rules and targets (#2101)

cloud/amazon/cloudwatchevent_rule.py

@@ -0,0 +1,409 @@
+#!/usr/bin/python
+# This file is part of Ansible
+#
+# Ansible is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+DOCUMENTATION = '''
+---
+module: cloudwatchevent_rule
+short_description: Manage CloudWatch Event rules and targets
+description:
+  - This module creates and manages CloudWatch event rules and targets.
+version_added: "2.2"
+extends_documentation_fragment:
+  - aws
+author: "Jim Dalton (@jsdalton) <jim.dalton@gmail.com>"
+requirements:
+  - python >= 2.6
+  - boto3
+notes:
+  - A rule must contain at least an I(event_pattern) or I(schedule_expression). A
+    rule can have both an I(event_pattern) and a I(schedule_expression), in which
+    case the rule will trigger on matching events as well as on a schedule.
+  - When specifying targets, I(input) and I(input_path) are mutually-exclusive
+    and optional parameters.
+options:
+  name:
+    description:
+      - The name of the rule you are creating, updating or deleting. No spaces
+        or special characters allowed (i.e. must match C([\.\-_A-Za-z0-9]+))
+    required: true
+  schedule_expression:
+    description:
+      - A cron or rate expression that defines the schedule the rule will
+        trigger on. For example, C(cron(0 20 * * ? *)), C(rate(5 minutes))
+    required: false
+  event_pattern:
+    description:
+      - A string pattern (in valid JSON format) that is used to match against
+        incoming events to determine if the rule should be triggered
+    required: false
+  state:
+    description:
+      - Whether the rule is present (and enabled), disabled, or absent
+    choices: ["present", "disabled", "absent"]
+    default: present
+    required: false
+  description:
+    description:
+      - A description of the rule
+    required: false
+  role_arn:
+    description:
+      - The Amazon Resource Name (ARN) of the IAM role associated with the rule
+    required: false
+  targets:
+    description:
+      - "A dictionary array of targets to add to or update for the rule, in the
+        form C({ id: [string], arn: [string], input: [valid JSON string], input_path: [valid JSONPath string] }).
+        I(id) [required] is the unique target assignment ID. I(arn) (required)
+        is the Amazon Resource Name associated with the target. I(input)
+        (optional) is a JSON object that will override the event data when
+        passed to the target.  I(input_path) (optional) is a JSONPath string
+        (e.g. C($.detail)) that specifies the part of the event data to be
+        passed to the target. If neither I(input) nor I(input_path) is
+        specified, then the entire event is passed to the target in JSON form."
+    required: false
+'''
+
+EXAMPLES = '''
+- cloudwatchevent_rule:
+    name: MyCronTask
+    schedule_expression: "cron(0 20 * * ? *)"
+    description: Run my scheduled task
+    targets:
+      - id: MyTargetId
+        arn: arn:aws:lambda:us-east-1:123456789012:function:MyFunction
+
+- cloudwatchevent_rule:
+    name: MyDisabledCronTask
+    schedule_expression: "cron(5 minutes)"
+    description: Run my disabled scheduled task
+    state: disabled
+    targets:
+      - id: MyOtherTargetId
+        arn: arn:aws:lambda:us-east-1:123456789012:function:MyFunction
+        input: '{"foo": "bar"}'
+
+- cloudwatchevent_rule: name=MyCronTask state=absent
+'''
+
+RETURN = '''
+rule:
+    description: CloudWatch Event rule data
+    returned: success
+    type: dict
+    sample: "{ 'arn': 'arn:aws:events:us-east-1:123456789012:rule/MyCronTask', 'description': 'Run my scheduled task', 'name': 'MyCronTask', 'schedule_expression': 'cron(0 20 * * ? *)', 'state': 'ENABLED' }"
+targets:
+    description: CloudWatch Event target(s) assigned to the rule
+    returned: success
+    type: list
+    sample: "[{ 'arn': 'arn:aws:lambda:us-east-1:123456789012:function:MyFunction', 'id': 'MyTargetId' }]"
+'''
+
+
+class CloudWatchEventRule(object):
+    def __init__(self, module, name, client, schedule_expression=None,
+                 event_pattern=None, description=None, role_arn=None):
+        self.name = name
+        self.client = client
+        self.changed = False
+        self.schedule_expression = schedule_expression
+        self.event_pattern = event_pattern
+        self.description = description
+        self.role_arn = role_arn
+
+    def describe(self):
+        """Returns the existing details of the rule in AWS"""
+        try:
+            rule_info = self.client.describe_rule(Name=self.name)
+        except botocore.exceptions.ClientError, e:
+            error_code = e.response.get('Error', {}).get('Code')
+            if error_code == 'ResourceNotFoundException':
+                return {}
+            raise
+        return self._snakify(rule_info)
+
+    def put(self, enabled=True):
+        """Creates or updates the rule in AWS"""
+        request = {
+            'Name': self.name,
+            'State': "ENABLED" if enabled else "DISABLED",
+        }
+        if self.schedule_expression:
+            request['ScheduleExpression'] = self.schedule_expression
+        if self.event_pattern:
+            request['EventPattern'] = self.event_pattern
+        if self.description:
+            request['Description'] = self.description
+        if self.role_arn:
+            request['RoleArn'] = self.role_arn
+        response = self.client.put_rule(**request)
+        self.changed = True
+        return response
+
+    def delete(self):
+        """Deletes the rule in AWS"""
+        self.remove_all_targets()
+        response = self.client.delete_rule(Name=self.name)
+        self.changed = True
+        return response
+
+    def enable(self):
+        """Enables the rule in AWS"""
+        response = self.client.enable_rule(Name=self.name)
+        self.changed = True
+        return response
+
+    def disable(self):
+        """Disables the rule in AWS"""
+        response = self.client.disable_rule(Name=self.name)
+        self.changed = True
+        return response
+
+    def list_targets(self):
+        """Lists the existing targets for the rule in AWS"""
+        try:
+            targets = self.client.list_targets_by_rule(Rule=self.name)
+        except botocore.exceptions.ClientError, e:
+            error_code = e.response.get('Error', {}).get('Code')
+            if error_code == 'ResourceNotFoundException':
+                return []
+            raise
+        return self._snakify(targets)['targets']
+
+    def put_targets(self, targets):
+        """Creates or updates the provided targets on the rule in AWS"""
+        if not targets:
+            return
+        request = {
+            'Rule': self.name,
+            'Targets': self._targets_request(targets),
+        }
+        response = self.client.put_targets(**request)
+        self.changed = True
+        return response
+
+    def remove_targets(self, target_ids):
+        """Removes the provided targets from the rule in AWS"""
+        if not target_ids:
+            return
+        request = {
+            'Rule': self.name,
+            'Ids': target_ids
+        }
+        response = self.client.remove_targets(**request)
+        self.changed = True
+        return response
+
+    def remove_all_targets(self):
+        """Removes all targets on rule"""
+        targets = self.list_targets()
+        return self.remove_targets([t['id'] for t in targets])
+
+    def _targets_request(self, targets):
+        """Formats each target for the request"""
+        targets_request = []
+        for target in targets:
+            target_request = {
+                'Id': target['id'],
+                'Arn': target['arn']
+            }
+            if 'input' in target:
+                target_request['Input'] = target['input']
+            if 'input_path' in target:
+                target_request['InputPath'] = target['input_path']
+            targets_request.append(target_request)
+        return targets_request
+
+    def _snakify(self, dict):
+        """Converts cammel case to snake case"""
+        return camel_dict_to_snake_dict(dict)
+
+
+class CloudWatchEventRuleManager(object):
+    RULE_FIELDS = ['name', 'event_pattern', 'schedule_expression', 'description', 'role_arn']
+
+    def __init__(self, rule, targets):
+        self.rule = rule
+        self.targets = targets
+
+    def ensure_present(self, enabled=True):
+        """Ensures the rule and targets are present and synced"""
+        rule_description = self.rule.describe()
+        if rule_description:
+            # Rule exists so update rule, targets and state
+            self._sync_rule(enabled)
+            self._sync_targets()
+            self._sync_state(enabled)
+        else:
+            # Rule does not exist, so create new rule and targets
+            self._create(enabled)
+
+    def ensure_disabled(self):
+        """Ensures the rule and targets are present, but disabled, and synced"""
+        self.ensure_present(enabled=False)
+
+    def ensure_absent(self):
+        """Ensures the rule and targets are absent"""
+        rule_description = self.rule.describe()
+        if not rule_description:
+            # Rule doesn't exist so don't need to delete
+            return
+        self.rule.delete()
+
+    def fetch_aws_state(self):
+        """Retrieves rule and target state from AWS"""
+        aws_state = {
+            'rule': {},
+            'targets': [],
+            'changed': self.rule.changed
+        }
+        rule_description = self.rule.describe()
+        if not rule_description:
+            return aws_state
+
+        # Don't need to include response metadata noise in response
+        del rule_description['response_metadata']
+
+        aws_state['rule'] = rule_description
+        aws_state['targets'].extend(self.rule.list_targets())
+        return aws_state
+
+    def _sync_rule(self, enabled=True):
+        """Syncs local rule state with AWS"""
+        if not self._rule_matches_aws():
+            self.rule.put(enabled)
+
+    def _sync_targets(self):
+        """Syncs local targets with AWS"""
+        # Identify and remove extraneous targets on AWS
+        target_ids_to_remove = self._remote_target_ids_to_remove()
+        if target_ids_to_remove:
+            self.rule.remove_targets(target_ids_to_remove)
+
+        # Identify targets that need to be added or updated on AWS
+        targets_to_put = self._targets_to_put()
+        if targets_to_put:
+            self.rule.put_targets(targets_to_put)
+
+    def _sync_state(self, enabled=True):
+        """Syncs local rule state with AWS"""
+        remote_state = self._remote_state()
+        if enabled and remote_state != 'ENABLED':
+            self.rule.enable()
+        elif not enabled and remote_state != 'DISABLED':
+            self.rule.disable()
+
+    def _create(self, enabled=True):
+        """Creates rule and targets on AWS"""
+        self.rule.put(enabled)
+        self.rule.put_targets(self.targets)
+
+    def _rule_matches_aws(self):
+        """Checks if the local rule data matches AWS"""
+        aws_rule_data = self.rule.describe()
+
+        # The rule matches AWS only if all rule data fields are equal
+        # to their corresponding local value defined in the task
+        return all([
+            getattr(self.rule, field) == aws_rule_data.get(field, None)
+            for field in self.RULE_FIELDS
+        ])
+
+    def _targets_to_put(self):
+        """Returns a list of targets that need to be updated or added remotely"""
+        remote_targets = self.rule.list_targets()
+        return [t for t in self.targets if t not in remote_targets]
+
+    def _remote_target_ids_to_remove(self):
+        """Returns a list of targets that need to be removed remotely"""
+        target_ids = [t['id'] for t in self.targets]
+        remote_targets = self.rule.list_targets()
+        return [
+            rt['id'] for rt in remote_targets if rt['id'] not in target_ids
+        ]
+
+    def _remote_state(self):
+        """Returns the remote state from AWS"""
+        description = self.rule.describe()
+        if not description:
+            return
+        return description['state']
+
+
+def get_cloudwatchevents_client(module):
+    """Returns a boto3 client for accessing CloudWatch Events"""
+    try:
+        region, ec2_url, aws_conn_kwargs = get_aws_connection_info(module,
+                                                                   boto3=True)
+        if not region:
+            module.fail_json(msg="Region must be specified as a parameter, in \
+                             EC2_REGION or AWS_REGION environment variables \
+                             or in boto configuration file")
+        return boto3_conn(module, conn_type='client',
+                          resource='events',
+                          region=region, endpoint=ec2_url,
+                          **aws_conn_kwargs)
+    except boto3.exception.NoAuthHandlerFound, e:
+        module.fail_json(msg=str(e))
+
+
+def main():
+    argument_spec = ec2_argument_spec()
+    argument_spec.update(dict(
+        name                 = dict(required=True),
+        schedule_expression  = dict(),
+        event_pattern        = dict(),
+        state                = dict(choices=['present', 'disabled', 'absent'],
+                                    default='present'),
+        description          = dict(),
+        role_arn             = dict(),
+        targets              = dict(type='list', default=[]),
+    ))
+    module = AnsibleModule(argument_spec=argument_spec)
+
+    if not HAS_BOTO3:
+        module.fail_json(msg='boto3 required for this module')
+
+    rule_data = dict(
+        [(rf, module.params.get(rf)) for rf in CloudWatchEventRuleManager.RULE_FIELDS]
+    )
+    targets = module.params.get('targets')
+    state = module.params.get('state')
+
+    cwe_rule = CloudWatchEventRule(module,
+                                   client=get_cloudwatchevents_client(module),
+                                   **rule_data)
+    cwe_rule_manager = CloudWatchEventRuleManager(cwe_rule, targets)
+
+    if state == 'present':
+        cwe_rule_manager.ensure_present()
+    elif state == 'disabled':
+        cwe_rule_manager.ensure_disabled()
+    elif state == 'absent':
+        cwe_rule_manager.ensure_absent()
+    else:
+        module.fail_json(msg="Invalid state '{0}' provided".format(state))
+
+    module.exit_json(**cwe_rule_manager.fetch_aws_state())
+
+
+# import module snippets
+from ansible.module_utils.basic import *
+from ansible.module_utils.ec2 import *
+
+
+if __name__ == '__main__':
+    main()