AWS EC2 autoscaling

please suggest userdata script for this

Here's an example, you need to put the actual IP (or DNS name) for the EFS mountpoint in place of the terraform resource that I used in my code, as well as having an EFS filesystem and mountpoint(s) already created:

mkdir /uploads
echo "${aws_efs_mount_target.EFS_Mountpoint.ip_address}:/ /uploads nfs4 rw,vers=4.1 0 0" >> /etc/fstab
mount -a
while [[ `mount | grep uploads | cut -d ' ' -f5` != "nfs4" ]]; do sleep 5; mount -a; done

About 1 time in 20 I found that the EFS filesystem wouldn't mount when the instance was provisioned, the while loop is to guard against this and re-try if it happens.