add a test play for testing rolling deploys

playbooks/edx-east/test-rolling.yml

+- hosts: all
+  sudo: true
+  vars:
+    # By default take instances in and out of the elb(s) they
+    # are attached to
+    # To skip elb operations use "-e elb_pre_post=fase"
+    elb_pre_post: true
+    # Number of instances to operate on at a time
+    serial_count: 1
+  serial: "{{ serial_count }}"
+  pre_tasks:
+    - action: ec2_facts
+      when: elb_pre_post
+    - debug: var="{{ ansible_ec2_instance_id }}"
+      when: elb_pre_post
+    - name: Instance De-register
+      local_action: ec2_elb_local_1.6.2
+      args:
+        instance_id: "{{ ansible_ec2_instance_id }}"
+        region: us-east-1
+        state: absent
+      sudo: False
+      when: elb_pre_post
+  tasks:
+    - shell: echo "test"
+  post_tasks:
+    - debug: var="{{ ansible_ec2_instance_id }}"
+      when: elb_pre_post
+    - name: Register instance in the elb
+      local_action: ec2_elb_local_1.6.2
+      args:
+        instance_id: "{{ ansible_ec2_instance_id }}"
+        ec2_elbs: "{{ item }}"
+        region: us-east-1
+        state: present
+      with_items: ec2_elbs
+      sudo: False
+      when: elb_pre_post