fix: powervs proxy nodnsupdate

ibmcloud_vs/powervs_interconnect_proxy_provision/build_dns_update.tf

@@ -77,6 +77,16 @@ fi
 EOF
   }
 
+  provisioner "file" {
+    destination = "/tmp/nodnsupdate"
+    content     = <<EOF
+#!/bin/sh
+make_resolv_conf() {
+    :
+}
+EOF
+  }
+
   connection {
     # The Bastion host ssh connection is established first, and then the host connection will be made from there.
     # Checking Host Key is false when not using bastion_host_key
@@ -98,13 +108,20 @@ resource "null_resource" "dns_resolv_update" {
 
   depends_on = [null_resource.dns_resolv_files]
 
+  # /etc/resolv.conf error 'generated by /usr/sbin/dhclient-script' on some OS Images, avoid overwritten file by 60s sleep
+  # then configure RHEL nmcli and using script '/etc/dhcp/dhclient-enter-hooks.d/nodnsupdate'
   provisioner "local-exec" {
     command = "echo '----Sleep 60s to ensure Virtual Server is ready-----' && sleep 60"
   }
 
   provisioner "remote-exec" {
     inline = [
       "echo 'Change DNS in resolv.conf'",
+      "os_info_id=$(grep ^ID= /etc/os-release | cut -d '=' -f2 | tr -d '\\\"')",
+      "if [ \"$os_info_id\" = \"rhel\" ] ; then nm_device_primary=$(ip route show default 0.0.0.0/0 | awk '/default/ {print $5}' | uniq) && nm_conn_primary=$(nmcli -t device show | grep 'CONNECTION' | sed 's/GENERAL.CONNECTION://') ; fi",
+      "if [ \"$os_info_id\" = \"rhel\" ] ; then nmcli device modify \"$nm_device_primary\" ipv4.ignore-auto-dns yes && nmcli connection modify \"$nm_conn_primary\" ipv4.ignore-auto-dns yes && systemctl reload NetworkManager ; fi",
+      "if [ -f /tmp/resolv.conf ]; then mkdir -p '/etc/dhcp/dhclient-enter-hooks.d' && mv /tmp/nodnsupdate /etc/dhcp/dhclient-enter-hooks.d/ ; fi",
+      "chmod +x /etc/dhcp/dhclient-enter-hooks.d/nodnsupdate",
       "if [ -f /tmp/resolv.conf ]; then mv /etc/resolv.conf /etc/resolv.conf.backup && mv /tmp/resolv.conf /etc/ ; fi",
       "chmod 644 /etc/resolv.conf",
       "chmod +x $HOME/terraform_dig.sh ; bash $HOME/terraform_dig.sh"