How to add a security group to a running EC2 Instance?

Question

I have an Amazon EC2 instance running and I will like to add another security group to that instance and then remove the current security group from that instance. Is this possible?

Answer 1

Amazon's FAQ says it's not possible to define a security group anywhere but at launch time.

Answer 2

1. Create an AMI image from the instance you want to move to a different security group.
2. Launch a new instance using that image, now we can assign this new instance to a different security group.
3. Discard the previous instance.

This requires downtime on your instance. There may be some other options available using the API.

Answer 3

As towo said you can't change a security group of an instance anywhere but launch time.

Unless you are using a VPC where security groups differ from EC2 security groups.

This page outlines the differences between EC2 and VPC security groups.

http://docs.amazonwebservices.com/AmazonVPC/latest/UserGuide/VPC_SecurityGroups.html

So if you require the extra functionality of the VPC groups (Changing groups, control ingress/engress traffic, etc.), you may want to look at the additional functionality provided by VPCs.

Answer 4

However according the this FAQ "modify the settings for the current security group - which will affect all instances running in the specific group" you can change gradually redefine the existing ones. As I'm trying this now for my scenario through the EC2 console, my records where all erased!