Terraform: How to config null_resource with murtiply connection - amazon-web-services

Question

Suppose that the ec2 module has two server, dynamic created. Like:
module "ec2-web" {
source = "terraform-aws-modules/ec2-instance/aws"
version = "4.1.4"
count = 2
name = "${local.appName}-webserver-${count.index + 1}"
.....
}
Now I have a null_resource config file, which has a connection only:
resource "null_resource" "web-upload" {
depends_on = [module.ec2-web]
connection {
type = "ssh"
host = module.ec2-web[0].public_ip
user = "ec2-user"
password = ""
private_key = file("keypair/a-ssh-key.pem")
timeout = "2m"
}
provisioner "remote-exec" {
inline = [
"sudo mkdir -p /var/www/html",
"sudo chown -R ec2-user:ec2-user /var/www/html",
]
}
provisioner "file" {
source = "web/"
destination = "/var/www/html"
}
}
Now how should I update any config can let finally terraform upload files to both server accordingly?

Answer 1

You would use the same approach with the count meta-argument:
resource "null_resource" "web-upload" {
count = 2
connection {
type = "ssh"
host = module.ec2-web[count.index].public_ip
user = "ec2-user"
password = ""
private_key = file("keypair/a-ssh-key.pem")
timeout = "2m"
}
provisioner "remote-exec" {
inline = [
"sudo mkdir -p /var/www/html",
"sudo chown -R ec2-user:ec2-user /var/www/html",
]
}
provisioner "file" {
source = "web/"
destination = "/var/www/html"
}
}
The explicit dependency using depends_on meta-argument is not required as the reference to the module output is used (module.ec2-web[count.index].public_ip). This means terraform will wait for the module to be done with creating resources prior to attempting the null_resource.