How To recover keys or connect to EC2(EBS) instance via user-data

In this post, let us see how to recover keys for EC2 instance(EBS) whose keys is lost 

Pre-requisites:

• AWS Account login and access
• Permission or access to launch EC2

Getting Started :

• Create an EC2 of your choice(I use Amazon Linux2 here); note that i dont have any role attached to this 

 The above instance is the key pair is lost

• Create a new key pair from AWS EC2 Console

 

   Key pair will be created will look like this

• Generate private key from this key pair; Connect to puttygen and open the acg-amz.pem file which is just generated and downloaded in local. Click on generate 'Public key' save it as 'acg-amz.ppk' to connect to putty connections

• stop the instance now to amend the user data 

• Select the instance, click on Action -> Instance settings -> View/Change user data. Copy the below data

• Start the instance and connect using SSH and see the connection taken successfully, because the new public key has been copied via user data

 Note:

1. If the user data is not getting applied, then amend the [user-groups, once] tp [user-groups, always]
2. Generate public key using puttygen or from ssh-keygen module from any other instance and use the same in user data
3. IP Address might change when this process takes place