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lambda_function.py
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lambda_function.py
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#!/usr/bin/env python
#
# Copyright (c) 2017 Naoto Yokoyama
#
# Modifications applied to the original work.
#
#
# Original copyright notice:
#
# Copyright 2015 Robb Wagoner
#
# 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.
#
'''
Parse an SNS event message and send to a Slack Channel
'''
import os
import json
import base64
import re
import requests
from base64 import b64decode
__author__ = "Robb Wagoner (@robbwagoner)"
__copyright__ = "Copyright 2015 Robb Wagoner"
__credits__ = ["Robb Wagoner"]
__license__ = "Apache License, 2.0"
__version__ = "0.1.2"
__maintainer__ = "Robb Wagoner"
__email__ = "robb@pandastrike.com"
__status__ = "Production"
DEFAULT_USERNAME = os.environ.get('DEFAULT_USERNAME', 'AWS Lambda')
DEFAULT_CHANNEL = os.environ.get('DEFAULT_CHANNEL', '#webhook-tests')
DEFAULT_EMOJI = os.environ.get('DEFAULT_EMOJI', ':information_source:')
USERNAME_PREFIX = os.environ.get('USERNAME_PREFIX', '')
def get_slack_emoji(event_src, topic_name, event_cond='default'):
'''Map an event source, severity, and condition to an emoji
'''
emoji_map = {
'autoscaling': {
'notices': {'default': ':scales:'}},
'cloudwatch': {
'notices': {
'ok': ':ok:',
'alarm': ':fire:',
'insuffcient_data': ':question:'},
'alerts': {
'ok': ':ok:',
'alarm': ':fire:',
'insuffcient_data': ':question:'}},
'codepipeline': {
'notices': {
'STARTED': ':ok:',
'FAILED': ':fire:',
'SUCCEEDED': ':ok:'}},
'elasticache': {
'notices': {'default': ':stopwatch:'}},
'rds': {
'notices': {'default': ':registered:'}}}
try:
return emoji_map[event_src][topic_name][event_cond]
except KeyError:
if topic_name == 'alerts':
return ':fire:'
else:
return DEFAULT_EMOJI
def get_slack_username(event_src):
'''Map event source to the Slack username
'''
username_map = {
'cloudwatch': 'AWS CloudWatch',
'autoscaling': 'AWS AutoScaling',
'elasticache': 'AWS ElastiCache',
'codepipeline': 'AWS CodePipeline',
'rds': 'AWS RDS'}
try:
return "{0}{1}".format(USERNAME_PREFIX, username_map[event_src])
except KeyError:
return DEFAULT_USERNAME
def get_slack_channel(region, event_src, topic_name, channel_map):
'''Map region and event type to Slack channel name
'''
try:
return channel_map[topic_name]
except KeyError:
return DEFAULT_CHANNEL
def autoscaling_capacity_change(cause):
'''
'''
s = re.search(r'capacity from (\w+ to \w+)', cause)
if s:
return s.group(0)
def lambda_handler(event, context):
'''The Lambda function handler
'''
config = {
'webhook_url': os.environ['WEBHOOK_URL'],
'channel_map': json.loads(base64.b64decode(os.environ['CHANNEL_MAP']))
}
event_cond = 'default'
sns = event['Records'][0]['Sns']
print('DEBUG EVENT:', sns['Message'])
try:
json_msg = json.loads(sns['Message'])
except ValueError as e:
json_msg = {}
if sns['Subject']:
message = sns['Subject']
else:
message = sns['Message']
# https://api.slack.com/docs/attachments
attachments = []
if json_msg.get('AlarmName'):
event_src = 'cloudwatch'
event_cond = json_msg['NewStateValue']
color_map = {
'OK': 'good',
'INSUFFICIENT_DATA': 'warning',
'ALARM': 'danger'
}
attachments = [{
'fallback': json_msg,
'message': json_msg,
'color': color_map[event_cond],
"fields": [{
"title": "Alarm",
"value": json_msg['AlarmName'],
"short": True
}, {
"title": "Status",
"value": json_msg['NewStateValue'],
"short": True
}, {
"title": "Description",
"value": json_msg['AlarmDescription'],
"short": False
}, {
"title": "Reason",
"value": json_msg['NewStateReason'],
"short": False
}]
}]
elif json_msg.get('Cause'):
event_src = 'autoscaling'
attachments = [{
"text": "Details",
"fallback": message,
"color": "good",
"fields": [{
"title": "Capacity Change",
"value": autoscaling_capacity_change(json_msg['Cause']),
"short": True
}, {
"title": "Event",
"value": json_msg['Event'],
"short": False
}, {
"title": "Cause",
"value": json_msg['Cause'],
"short": False
}]
}]
elif json_msg.get('ElastiCache:SnapshotComplete'):
event_src = 'elasticache'
attachments = [{
"text": "Details",
"fallback": message,
"color": "good",
"fields": [{
"title": "Event",
"value": "ElastiCache Snapshot"
}, {
"title": "Message",
"value": "Snapshot Complete"
}]
}]
elif re.match("RDS", sns.get('Subject') or ''):
event_src = 'rds'
attachments = [{
"fields": [{
"title": "Source",
"value": "{0} '{1}'".format(json_msg['Event Source'], json_msg['Source ID'])
},{
"title": "Message",
"value": json_msg['Event Message']
}]}]
if json_msg.get('Identifier Link'):
title_arr = json_msg['Identifier Link'].split('\n')
if len(title_arr) >= 2:
title_str = title_arr[1]
title_lnk_str = title_arr[0]
else:
title_str = title_lnk_str = title_arr[0]
attachments[0]['fields'].append({
"title": "Details",
"value": "<{0}|{1}>".format(title_str, title_lnk_str)
})
elif json_msg.get('source') == 'aws.codepipeline':
event_src = 'codepipeline'
message = json_msg.get('detail-type')
event_cond = json_msg.get('detail').get('state')
color_map = {
'STARTED': 'good',
'SUCCEEDED': 'good',
'FAILED': 'danger'
}
attachments = [{
'fallback': json_msg.get('detail-type'),
'color': color_map[event_cond],
"fields": [{
"title": "Pipeline",
"value": json_msg.get('detail').get('pipeline')
}, {
"title": "State",
"value": json_msg.get('detail').get('state')
}]
}]
else:
event_src = 'other'
# SNS Topic ARN: arn:aws:sns:<REGION>:<AWS_ACCOUNT_ID>:<TOPIC_NAME>
#
# SNS Topic Names => Slack Channels
# <env>-alerts => alerts-<region>
# <env>-notices => events-<region>
#
region = sns['TopicArn'].split(':')[3]
topic_name = sns['TopicArn'].split(':')[-1]
# event_env = topic_name.split('-')[0]
# event_sev = topic_name.split('-')[1]
# print('DEBUG:', topic_name, region, event_env, event_sev, event_src)
channel_map = config['channel_map']
payload = {
'text': message,
'channel': get_slack_channel(region, event_src, topic_name, channel_map),
'username': get_slack_username(event_src),
'icon_emoji': get_slack_emoji(event_src, topic_name, event_cond.lower())}
if attachments:
payload['attachments'] = attachments
print('DEBUG PAYLOAD:', json.dumps(payload))
webhook_url = config['webhook_url'] if re.match('^https://', config['webhook_url']) else f"https://{config['webhook_url']}"
r = requests.post(webhook_url, json=payload)
return r.status_code
# Test locally
if __name__ == '__main__':
sns_event_template = json.loads(r"""
{
"Records": [
{
"EventVersion": "1.0",
"EventSubscriptionArn": "arn:aws:sns:EXAMPLE",
"EventSource": "aws:sns",
"Sns": {
"SignatureVersion": "1",
"Timestamp": "1970-01-01T00:00:00.000Z",
"Signature": "EXAMPLE",
"SigningCertUrl": "EXAMPLE",
"MessageId": "95df01b4-ee98-5cb9-9903-4c221d41eb5e",
"Message": "{\"AlarmName\":\"sns-slack-test-from-cloudwatch-total-cpu\",\"AlarmDescription\":null,\"AWSAccountId\":\"123456789012\",\"NewStateValue\":\"OK\",\"NewStateReason\":\"Threshold Crossed: 1 datapoint (7.9053535353535365) was not greater than or equal to the threshold (8.0).\",\"StateChangeTime\":\"2015-11-09T21:19:43.454+0000\",\"Region\":\"US - N. Virginia\",\"OldStateValue\":\"ALARM\",\"Trigger\":{\"MetricName\":\"CPUUtilization\",\"Namespace\":\"AWS/EC2\",\"Statistic\":\"AVERAGE\",\"Unit\":null,\"Dimensions\":[],\"Period\":300,\"EvaluationPeriods\":1,\"ComparisonOperator\":\"GreaterThanOrEqualToThreshold\",\"Threshold\":8.0}}",
"MessageAttributes": {
"Test": {
"Type": "String",
"Value": "TestString"
},
"TestBinary": {
"Type": "Binary",
"Value": "TestBinary"
}
},
"Type": "Notification",
"UnsubscribeUrl": "EXAMPLE",
"TopicArn": "arn:aws:sns:us-east-1:123456789012:production-notices",
"Subject": "OK: sns-slack-test-from-cloudwatch-total-cpu"
}
}
]
}""")
print('running locally')
print(lambda_handler(sns_event_template, None))