May 5, 2016

Automated Blue/Green deployment using Lambda and CloudFormation

Blue/Green deployment is a well-known method to deploy an application without any downtime. Performing DNS switch is one of the very common techniques to achieve this. Using DNS switch has a minor issue with DNS caching which might take some time for DNS change to be propagated. Apart from DNS switch, AWS gives us two different options to switch the stacks. One is to have single ELB and swap it across auto-scaling group and another is switching the launch configuration of the auto-scaling group. Read more

December 20, 2015

Sending response back to CFN custom resource from python Lambda function

CloudFormation uses a pre-signed S3 URL to receive the response back from the custom resources managed by it. There are few blue prints available for Node.js Lambda custom resources but nothing available for python yet. Hence I created this simple function which shall be used to send the response back to CFN custom resource by performing PUT request to the pre-signed S3 URL. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 import json import requests def lambda_handler(event, context): responseStatus = 'SUCCESS' responseData = {} if event['RequestType'] == 'Delete': sendResponse(event, context, responseStatus, responseData) responseData = {'Success': 'Test Passed. Read more

December 7, 2015

Continuous Integration – Manage shared resources across accounts automatically

I prefer creating the base AMI using packer; RDS snapshot using a Jenkins job which get triggered whenever there is a change in the database schema in the SCM. In case of installers, binaries, etc. it would be best to store them in a single S3 bucket. In all the above mentioned scenarios I prefer to share those resources to a 3rdparty AWS account and remove the share when not needed. Read more

November 29, 2015

Executing Ruby code in AWS Lambda

AWS Lambda supports only Java, JavaScript & Python at the time of writing this post. I was wondering whether I can exploit the Lambda to execute chef’s knifecommands on it since Lambda runs on a Linux container. Using simple python function I have identified that the code of the Lambda function gets copied to /var/task and executed from there. I decided to custom build ruby as embedded platform similar to how chef-clientor chefdkare distributed. Read more

November 27, 2015

Automated cross account DNS management through CFN and API access through API gateway

It’s a general best practice to manage all DNS entries in Route53 in a centralized AWS account. In that case it is difficult to automate the DNS record creation/deletion based on resources created in another AWS account using CloudFormation. CloudFormation doesn’t yet have the capability to create resources in a different AWS account. Combining IAM role delegation, AWS Lambda & CFN Custom resources provides us a solution. I have extended the same solution by exposing the Lambda function through API gateway which provides a powerful mechanism. Read more

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