Ensure /etc/resolv.conf content for CoreOS

Use cloud-init config to replace /etc/resolv.conf with the
content for kubelet to properly configure hostnet pods.

Do not use systemd-resolved yet, see
https://coreos.com/os/docs/latest/configuring-dns.html
"Only nss-aware applications can take advantage of the
systemd-resolved cache. Notably, this means that statically
linked Go programs and programs running within Docker/rkt
will use /etc/resolv.conf only, and will not use the
systemd-resolve cache."

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>

roles/dnsmasq/defaults/main.yml

@@ -11,6 +11,10 @@
 #nameservers:
 #  - 127.0.0.1
 
+# CoreOS cloud init config file to define /etc/resolv.conf content
+# for hostnet pods and infra needs
+resolveconf_cloud_init_conf: /etc/resolveconf_cloud_init.conf
+
 # Versions
 dnsmasq_version: 2.72