I'm trying to use userdata to run some code on autoscaled EC2 instances. It's important that the instance tags ("name", etc) are already set. I know that doesn't happen immediately on creation.
As a start, I'm adding sleep 20 in my userdata script. Obviously that's a code smell.
So, how long does it take tags to propagate? How can I detect it- can I use instance metadata (http://169.254.169.254/latest/) to detect that the machine is healthy?
If not, I know I could determine my instance ID and then query the API (perhaps with boto) and wait for tags. There are several yaks necessary to do this- for instance, I must ensure dependencies are installed and that I have IAM Role rights. So I'd prefer not to go that route.