Add flannel vars to enable vagrant and amazon environments

roles/network_plugin/defaults/main.yml

+---
+## defines the IP used to talk to the node
+# flannel_public_ip:
+
+## interface that should be used for flannel operations
+# flannel_interface:

roles/network_plugin/templates/flannel/flannel-pod.yml

@@ -31,7 +31,7 @@
         command:
           - "/bin/sh"
           - "-c"
-          - "/opt/bin/flanneld -etcd-endpoints {% for srv in groups['etcd'] %}http://{{ srv }}:2379{% if not loop.last %},{% endif %}{% endfor %} -etcd-prefix /{{ cluster_name }}/network 1>>/var/log/flannel_server.log 2>&1"
+          - "/opt/bin/flanneld -etcd-endpoints {% for srv in groups['etcd'] %}http://{{ srv }}:2379{% if not loop.last %},{% endif %}{% endfor %} -etcd-prefix /{{ cluster_name }}/network {% if flannel_interface is defined %}-iface {{ flannel_interface }}{% endif %} {% if flannel_public_ip is defined %}-public-ip {{ flannel_public_ip }}{% endif %} 1>>/var/log/flannel_server.log 2>&1"
         ports:
           - hostPort: 10253
             containerPort: 10253