How does Amazon ec2 user-data work

Question

When we start instances and pass in the user-data, when is the data transmitted to the VM and where is it stored?

My first take on it was it is set as the USER_DATA env var, but we can also pass it as a file. So, the next question is where is that file stored? Is it generic to all instances or varies depending on AMI?

Answer 1

Refer these:

·         http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html

·         http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/user-data.html

To throw some light on your queries.

User-data is available to the instance with a simple HTTP request at this URL:

http://169.254.169.254/latest/user-data