Tuesday, November 14, 2017

ARN AWS - What is it and how can i make one for a resource?

If you are into AWS coding and access AWS resources , assign policy to user in AWS  pragmatically than you will be working with ARN a lot

The below 2 links are very handy to work with ARN

What is ARN 

How to define one?

Saturday, October 28, 2017

Instance does not have a volume attached at root (/dev/sda1)

Error :Instance does not have a volume attached at root (/dev/sda1) 

The error occurs when either a boot volume is missing or mapped to wrong device name. In this case EC2 instance is expecting the boot device name /dev/sda1 to be connected to the EC2 instance and unable to find it

The step is valid for EC2 instances is backed by EBS volumes i.e EBS is used for boot volumes rather than Instance Store

Note: To Understand more about Instance backed store and EBS backed store
refer this article Amazon EC2 Root Device Volume

To attach a root volume follow these steps.

  • Create   a new EBS Volume. Click on Volumes when in EC2 Instance page

  • Once EBS volume is created , right click and select Attach Volume
  • Select the EC2 instance in second textbox and enter the device name as "/dev/sda1"

  • Click Attach and restart the EC2 instance 

 Do leave comment if the solution works and even if it doesn't work . Thanks!

node -v ReferenceError: node is not defined

Trying to make node.js work with command node -v and end up with an error 

node -v ReferenceError: node is not defined 

You are probably trying to run the command in REPL  virtual environment

In order to check node.js version go to the folder with node.js files and run command from command prompt 

About REPL 

REPL ( Read- Eval-Print -Loop) is an virtual environment that comes with Node.js. It is tool to test simple Node.js javascript code. 

Tuesday, August 29, 2017

AWS Costing

If you ask any AWS geek , what is the biggest change they have noticed after moving On-Prem workloads to Cloud, you will mostly hear typical well known answers "better management" , "Less Operations overhead "...so on ..

One important trait which they aquire but will not acknowledge as they are not aware either is acquiring  a  "Mulah mindset" . [ for those who are wondering what mulah is, let me make it simple. mulah ~ money"]

Be an  Architect , IT manager, Developer one thing you need to be good at when working with AWS is costing. I know its hard , never had to deal with costing before so frequently  as old school style only involved painful money discussion during the budget cycle  when capital investment needs to be budgeted during initial stages of planning. 

Good part is, you don't need to have a Phd to understand costing but do need to spend some effort to get used to calculation. [ Paradigm shift is good thing]

AWS provides some good tools and lots of information to make life easier . Below are some useful links

Monday, August 28, 2017

AWS Elastic Beanstalk vs AWS CloudFormation

One question , i get in most of sessions when talking about Elastic Beanstalk is
"difference between Elastic beanstalk and CloudFormation"

I would like to keep this explanation very simple.

Use  Elastic Beanstalk when you want to deploy the application from supported developer tool and don't want to worry about provision of infrastructure prior to deployment. Elastic beanstalk framework will provision the infrastructure and deploy the code to servers.

Use CloudFormation  when you want a framework to define collection of related AWS resources and provision them in an orderly and predictable fashion

Important to Note 

AWS CloudFormation supports Elastic Beanstalk application environments as one of the AWS resource types

Detailed Information :


Elastic Beanstalk

Tuesday, July 11, 2017


Came across a very good , simple to understand comparison between AWS and DIY (Do-It Yourself)

Scale Up
Elastic Service(On-Demand/ When needed)
Assume Reliable Infrastructure
Assume Infrastructure Failure
Diverse Technical Expertise
Application Based Expertise
Application Unaware of Infrastructure
Application aware infrastructure
High Upfront Cost
Usage Based Cost
Design, Build, Operate
Limited Knowledge/ Shared Support
Showback , charge back challenging
Showback , Chargeback can be achieved by granular monitoring of usage

AWS vs Azure

Age old question .....

Check this comparison matrix


Gray Failures: What is it and how to detect one?

If you are reading this article , i guess you are curious to know about gray failures and different methods to detect gray failures.  Hopefu...