Adding more features.

- Implementing support for custom domains
- Blocking common link previewers to "unwind" the links
- Setting a log retention policy for the lambda functions
- Updating to latest CDK version (1.44)

app.py

@@ -1,11 +1,22 @@
 #!/usr/bin/env python3
 
-from aws_cdk import core
+import os
+from aws_cdk import (
+    core,
+    aws_route53 as route53)
 
-from once.once_stack import OnceStack
+from once.once_stack import OnceStack, CustomDomainStack
+
+USE_CUSTOM_DOMAIN = True
+DOMAIN_NAME = os.getenv('DOMAIN_NAME')
+HOSTED_ZONE_NAME = os.getenv('HOSTED_ZONE_NAME')
+HOSTED_ZONE_ID = os.getenv('HOSTED_ZONE_ID')
 
 
 app = core.App()
-OnceStack(app, "once")
+once = OnceStack(app, 'once',
+    custom_domain=DOMAIN_NAME,
+    hosted_zone_id=HOSTED_ZONE_ID,
+    hosted_zone_name=HOSTED_ZONE_NAME)
 
 app.synth()