Lambda function that takes ECS Cloudwatch events and sends a notification to Slack

lambda_function-ECS-cloudwatch-slack.py

# Written by Dane Fetterman on 12/1/2016
# https://aws.amazon.com/blogs/compute/monitor-cluster-state-with-amazon-ecs-event-stream/
# Where they use a cloud watch event from ECS to notify a SNS topic. We're 
# sending a notification directly to slack instead


import requests
import json
from boto3 import session, client

webhookurl = "https://hooks.slack.com/services/WHATEVERendpointYouGotFromSlack"

def lambda_handler(event, context):
    # Establish credentials
    session_var = session.Session()
    credentials = session_var.get_credentials()
    region = session_var.region_name or 'us-east-1'    
    if "detail-type" not in event:
        raise ValueError("ERROR: event object is not a valid CloudWatch Logs event")
    else:
        if event["detail-type"] == "ECS Task State Change":
            detail = event["detail"]
            if detail["lastStatus"] == "STOPPED":
                if detail["stoppedReason"] == "Essential container in task exited":
                  # Send an error status message.
                  url = webhookurl
                  Subject="ECS task failure detected for container",
                  Message=json.dumps(detail)
                  messagedata = json.loads(Message)
                  # Break out Cloudwatch payload into variables that we use
                  taskArn = messagedata['taskArn']
                  desiredStatus = messagedata['desiredStatus']
                  lastStatus = messagedata['lastStatus']
                  stoppedReason = messagedata['stoppedReason']
                  clusterArn = messagedata['clusterArn']
                  
                  taskDefinitionArn = messagedata['taskDefinitionArn']
                  # Get all content from nested containers param:
                  #containers = messagedata['containers']
                  # Get specific nested content from containers param:
                  containersreason = messagedata['containers'][0]['reason']
                  
                  #ALL DATA that was posted from cloudwatch## 
                  #payload = {'channel': '#builds', 'username': 'webhookbot', 'text': '%s ' % (messagedata), 'icon_emoji': 'ghostwn:', 'username': 'ECSLambda-Post-Bot', 'channel': '#builds' }
                  #Only post to slack with specific data from cloudwatch ##
                  payload = {'channel': '#builds', 'username': 'webhookbot', 'text': '%s \n Task ARN: %s \n Desired Status: %s \n Last Status: %s \n Stopped Reason: %s \n Reason: %s \n Cluster ARN: %s ' % (Subject, taskArn, desiredStatus, lastStatus, stoppedReason, containersreason, clusterArn, ), 'icon_emoji': 'ghostwn:', 'username': 'ECSLambda-Post-Bot', 'channel': '#builds' }
                  headers = {"content-type": "application/json" }
                  r = requests.put(url, data=json.dumps(payload), headers=headers)
                  
                  #print json.dumps(messagedata)
                  print r.status_code
                  print r.content
                  note = "Post of data to slack was attempted"

# some resources:
#https://api.slack.com/incoming-webhooks
#http://requestb.in/pehntype
#http://docs.aws.amazon.com/lambda/latest/dg/lambda-python-how-to-create-deployment-package.html