Implement update_user_pool_domain

Introduce the CognitoIDP's UpdateUserPoolDomain to update configuration
options of the associated domain to a Cognito IDP (e.g. ACM certificate).

IMPLEMENTATION_COVERAGE.md

@@ -928,6 +928,7 @@
 - [ ] update_user_attributes
 - [ ] update_user_pool
 - [X] update_user_pool_client
+- [X] update_user_pool_domain
 - [ ] verify_software_token
 - [ ] verify_user_attribute
 

moto/cognitoidp/models.py

@@ -2,6 +2,7 @@ from __future__ import unicode_literals
 
 import datetime
 import functools
+import hashlib
 import itertools
 import json
 import os
@@ -154,20 +155,37 @@ class CognitoIdpUserPool(BaseModel):
 
 class CognitoIdpUserPoolDomain(BaseModel):
 
-    def __init__(self, user_pool_id, domain):
+    def __init__(self, user_pool_id, domain, custom_domain_config=None):
         self.user_pool_id = user_pool_id
         self.domain = domain
+        self.custom_domain_config = custom_domain_config or {}
 
-    def to_json(self):
+    def _distribution_name(self):
+        if self.custom_domain_config and \
+                'CertificateArn' in self.custom_domain_config:
+            hash = hashlib.md5(
+                self.custom_domain_config['CertificateArn'].encode('utf-8')
+            ).hexdigest()
+            return "{hash}.cloudfront.net".format(hash=hash[:16])
+        return None
+
+    def to_json(self, extended=True):
+        distribution = self._distribution_name()
+        if extended:
             return {
                 "UserPoolId": self.user_pool_id,
                 "AWSAccountId": str(uuid.uuid4()),
-            "CloudFrontDistribution": None,
+                "CloudFrontDistribution": distribution,
                 "Domain": self.domain,
                 "S3Bucket": None,
                 "Status": "ACTIVE",
                 "Version": None,
             }
+        elif distribution:
+            return {
+                "CloudFrontDomain": distribution,
+            }
+        return None
 
 
 class CognitoIdpUserPoolClient(BaseModel):
@@ -338,11 +356,13 @@ class CognitoIdpBackend(BaseBackend):
         del self.user_pools[user_pool_id]
 
     # User pool domain
-    def create_user_pool_domain(self, user_pool_id, domain):
+    def create_user_pool_domain(self, user_pool_id, domain, custom_domain_config=None):
         if user_pool_id not in self.user_pools:
             raise ResourceNotFoundError(user_pool_id)
 
-        user_pool_domain = CognitoIdpUserPoolDomain(user_pool_id, domain)
+        user_pool_domain = CognitoIdpUserPoolDomain(
+            user_pool_id, domain, custom_domain_config=custom_domain_config
+        )
         self.user_pool_domains[domain] = user_pool_domain
         return user_pool_domain
 
@@ -358,6 +378,14 @@ class CognitoIdpBackend(BaseBackend):
 
         del self.user_pool_domains[domain]
 
+    def update_user_pool_domain(self, domain, custom_domain_config):
+        if domain not in self.user_pool_domains:
+            raise ResourceNotFoundError(domain)
+
+        user_pool_domain = self.user_pool_domains[domain]
+        user_pool_domain.custom_domain_config = custom_domain_config
+        return user_pool_domain
+
     # User pool client
     def create_user_pool_client(self, user_pool_id, extended_config):
         user_pool = self.user_pools.get(user_pool_id)

moto/cognitoidp/responses.py

@@ -50,7 +50,13 @@ class CognitoIdpResponse(BaseResponse):
     def create_user_pool_domain(self):
         domain = self._get_param("Domain")
         user_pool_id = self._get_param("UserPoolId")
-        cognitoidp_backends[self.region].create_user_pool_domain(user_pool_id, domain)
+        custom_domain_config = self._get_param("CustomDomainConfig")
+        user_pool_domain = cognitoidp_backends[self.region].create_user_pool_domain(
+            user_pool_id, domain, custom_domain_config
+        )
+        domain_description = user_pool_domain.to_json(extended=False)
+        if domain_description:
+            return json.dumps(domain_description)
         return ""
 
     def describe_user_pool_domain(self):
@@ -69,6 +75,17 @@ class CognitoIdpResponse(BaseResponse):
         cognitoidp_backends[self.region].delete_user_pool_domain(domain)
         return ""
 
+    def update_user_pool_domain(self):
+        domain = self._get_param("Domain")
+        custom_domain_config = self._get_param("CustomDomainConfig")
+        user_pool_domain = cognitoidp_backends[self.region].update_user_pool_domain(
+            domain, custom_domain_config
+        )
+        domain_description = user_pool_domain.to_json(extended=False)
+        if domain_description:
+            return json.dumps(domain_description)
+        return ""
+
     # User pool client
     def create_user_pool_client(self):
         user_pool_id = self.parameters.pop("UserPoolId")

tests/test_cognitoidp/test_cognitoidp.py

@@ -133,6 +133,22 @@ def test_create_user_pool_domain():
     result["ResponseMetadata"]["HTTPStatusCode"].should.equal(200)
 
 
+@mock_cognitoidp
+def test_create_user_pool_domain_custom_domain_config():
+    conn = boto3.client("cognito-idp", "us-west-2")
+
+    domain = str(uuid.uuid4())
+    custom_domain_config = {
+        "CertificateArn": "arn:aws:acm:us-east-1:123456789012:certificate/123456789012",
+    }
+    user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
+    result = conn.create_user_pool_domain(
+        UserPoolId=user_pool_id, Domain=domain, CustomDomainConfig=custom_domain_config
+    )
+    result["ResponseMetadata"]["HTTPStatusCode"].should.equal(200)
+    result["CloudFrontDomain"].should.equal("e2c343b3293ee505.cloudfront.net")
+
+
 @mock_cognitoidp
 def test_describe_user_pool_domain():
     conn = boto3.client("cognito-idp", "us-west-2")
@@ -162,6 +178,23 @@ def test_delete_user_pool_domain():
     result["DomainDescription"].keys().should.have.length_of(0)
 
 
+@mock_cognitoidp
+def test_update_user_pool_domain():
+    conn = boto3.client("cognito-idp", "us-west-2")
+
+    domain = str(uuid.uuid4())
+    custom_domain_config = {
+        "CertificateArn": "arn:aws:acm:us-east-1:123456789012:certificate/123456789012",
+    }
+    user_pool_id = conn.create_user_pool(PoolName=str(uuid.uuid4()))["UserPool"]["Id"]
+    conn.create_user_pool_domain(UserPoolId=user_pool_id, Domain=domain)
+    result = conn.update_user_pool_domain(
+        UserPoolId=user_pool_id, Domain=domain, CustomDomainConfig=custom_domain_config
+    )
+    result["ResponseMetadata"]["HTTPStatusCode"].should.equal(200)
+    result["CloudFrontDomain"].should.equal("e2c343b3293ee505.cloudfront.net")
+
+
 @mock_cognitoidp
 def test_create_user_pool_client():
     conn = boto3.client("cognito-idp", "us-west-2")