Make null resource to wait on aws_route53_record in Terraform – CentOS

You can avoid the depends_on here by properly interpolating the value out of the resource instead:

resource "aws_route53_record" "record" {
    zone_id = data.aws_route53_zone.selected.zone_id
    name    = "${var.sfs_instance_name}.example.com"
    type    = "A"
    ttl     = "60"
    records = [aws_eip.sfs.public_ip]
  }

resource "null_resource" "sfs-ssl-certs" {

  connection {
    type        = "ssh"
    user        = "centos"
    host        = aws_eip.sfs.public_ip
    private_key = file("../keys/${var.sfs_instance_name}.pem")
  }

  provisioner "remote-exec" {
    inline = [
      "set -x",
      "sudo certbot --nginx -d ${aws_route53_record.record.name} --register-unsafely-without-email --agree-tos --force-renewal --non-interactive > /home/centos/get_cert.log"
    ]
}

Terraform only needs the depends_on parameter when it’s not possible to tell the other resource about the dependency chain directly by interpolating values of the resource into the other resources. In general if you can avoid using it and stick to direct resource interpolation then it makes things better. As another other positive side it avoids you having to build the DNS record name by string concatenation in two places.

The Terraform documentation around resource dependencies also suggest avoid depends_on unless absolutely necessary:

Most resources in a configuration don’t have any particular
relationship, and Terraform can make changes to several unrelated
resources in parallel.

However, some resources must be processed after other specific
resources; sometimes this is because of how the resource works, and
sometimes the resource’s configuration just requires information
generated by another resource.

Most resource dependencies are handled automatically. Terraform
analyses any expressions within a resource block to find references to
other objects, and treats those references as implicit ordering
requirements when creating, updating, or destroying resources. Since
most resources with behavioral dependencies on other resources also
refer to those resources’ data, it’s usually not necessary to manually
specify dependencies between resources.

However, some dependencies cannot be recognized implicitly in
configuration. For example, if Terraform must manage access control
policies and take actions that require those policies to be present,
there is a hidden dependency between the access policy and a resource
whose creation depends on it. In these rare cases, the depends_on
meta-argument can explicitly specify a dependency.