make max docker dns server configurable

inventory/group_vars/all.yml

@@ -83,6 +83,10 @@ bin_dir: /usr/local/bin
 ## Please note that overlay2 is only supported on newer kernels
 #docker_storage_options: -s overlay2
 
+# Maximum name servers for docker. If your host /etc/resolv.conf contains serval
+# nameservers, you may need to increase this.
+#docker_max_dns_servers: 3
+
 ## Default packages to install within the cluster, f.e:
 #kpm_packages:
 #  - name: kube-system/grafana

roles/docker/defaults/main.yml

@@ -8,3 +8,5 @@ docker_repo_key_info:
 
 docker_repo_info:
   repos:
+
+docker_max_dns_servers: 3

roles/docker/tasks/set_facts_dns.yml

@@ -53,7 +53,7 @@
 - name: check number of nameservers
   fail:
     msg: "Too many nameservers"
-  when: docker_dns_servers|length > 3
+  when: docker_dns_servers|length > docker_max_dns_servers|int
 
 - name: check number of search domains
   fail: