Remote-exec provisioner on gcp not connecting with host - ssh

Question

I'm trying to use remote-exec provisioner for a use-case related to my project on GCP using Terraform version 12, based on the format specified in terraform docs I get a known hosts key mismatch error after the provisioner timesout.
resource "google_compute_instance" "secondvm" {
name = "secondvm"
machine_type = "n1-standard-1"
zone = "us-central1-a"
boot_disk {
initialize_params {
image = "centos-7-v20190905"
}
}
network_interface {
network = "default"
access_config {
nat_ip = google_compute_address.second.address
network_tier = "PREMIUM"
}
}
#metadata = {
#ssh-keys = "root:${file("~/.ssh/id_rsa.pub")}"
#}
metadata_startup_script = "cd /; touch makefile.txt; sudo echo \"string xyz bgv\" >>./makefile.txt"
provisioner "remote-exec" {
inline = [
"sudo sed -i 's/xyz/google_compute_address.first.address/gI' /makefile.txt"
]
connection {
type = "ssh"
#port = 22
host = self.network_interface[0].access_config[0].nat_ip
user = "root"
timeout = "120s"
#agent = false
private_key = file("~/.ssh/id_rsa")
#host_key = file("~/.ssh/google_compute_engine.pub")
host_key = file("~/.ssh/id_rsa.pub")
}
}
depends_on = [google_compute_address.second]
}
I'm not sure what exactly I'm doing wrong with the keys here but the error I get is
google_compute_instance.secondvm: Still creating... [2m10s elapsed]
google_compute_instance.secondvm (remote-exec): Connecting to remote host via SSH...
google_compute_instance.secondvm (remote-exec): Host: 104.155.186.128
google_compute_instance.secondvm (remote-exec): User: root
google_compute_instance.secondvm (remote-exec): Password: false
google_compute_instance.secondvm (remote-exec): Private key: true
google_compute_instance.secondvm (remote-exec): Certificate: false
google_compute_instance.secondvm (remote-exec): SSH Agent: false
google_compute_instance.secondvm (remote-exec): Checking Host Key: true
google_compute_instance.secondvm: Still creating... [2m20s elapsed]
Error: timeout - last error: SSH authentication failed (root#104.155.186.128:22): ssh: handshake failed: knownhosts: key mismatch