Use double quotes everywhere.

playbooks/roles/edx_vpc/tasks/main.yml

@@ -32,11 +32,11 @@
 # to the vpc whose subnets and rts are not enumerated here.
 - name: create a vpc
   local_action:
-    module: 'ec2_vpc_local'
-    resource_tags: '{{ vpc_tags }}'
-    cidr_block: '{{ vpc_cidr }}'
-    region: '{{ vpc_aws_region }}'
-    state: '{{ vpc_state }}'
+    module: "ec2_vpc_local"
+    resource_tags: "{{ vpc_tags }}"
+    cidr_block: "{{ vpc_cidr }}"
+    region: "{{ vpc_aws_region }}"
+    state: "{{ vpc_state }}"
     internet_gateway: yes
     wait: yes
   register: created_vpc
@@ -100,9 +100,9 @@
 
 - name: create nat instance
   local_action:
-    module: 'ec2'
-    state: 'present'
-    wait: "yes"
+    module: "ec2"
+    state: "present"
+    wait: yes
     source_dest_check: false
     region: "{{ vpc_aws_region }}"
     profile: "{{ vpc_aws_profile }}"