Interface name is not always last token in output.

playbooks/roles/aws/tasks/main.yml

@@ -31,7 +31,7 @@
     - deploy
 
 - name: Get name of default network interface
-  shell: "ip route show 0/0 | awk '{print $NF}'"
+  shell: "ip route show 0/0 | grep -oP '(?<=dev )[[:alnum:]]+'"
   register: get_interface_name
   when: ansible_distribution in common_debian_variants