From 4ec748542f91c727147390685adf641a29a4e9e4 Mon Sep 17 00:00:00 2001
From: Viren Nadkarni <viren.nadkarni@gmail.com>
Date: Tue, 6 Dec 2022 02:50:03 +0530
Subject: [PATCH] EC2: AllocateAddress fallback domain (#5729)

---
 moto/ec2/exceptions.py                      |  7 -----
 moto/ec2/models/elastic_ip_addresses.py     |  3 +--
 moto/ec2/responses/elastic_ip_addresses.py  |  2 +-
 tests/test_ec2/test_elastic_ip_addresses.py | 30 ++++++++++-----------
 4 files changed, 16 insertions(+), 26 deletions(-)

diff --git a/moto/ec2/exceptions.py b/moto/ec2/exceptions.py
index a0938f6e0..bac72ceff 100644
--- a/moto/ec2/exceptions.py
+++ b/moto/ec2/exceptions.py
@@ -333,13 +333,6 @@ class VolumeInUseError(EC2ClientError):
         )
 
 
-class InvalidDomainError(EC2ClientError):
-    def __init__(self, domain):
-        super().__init__(
-            "InvalidParameterValue", f"Invalid value '{domain}' for domain."
-        )
-
-
 class InvalidAddressError(EC2ClientError):
     def __init__(self, ip):
         super().__init__("InvalidAddress.NotFound", f"Address '{ip}' not found.")
diff --git a/moto/ec2/models/elastic_ip_addresses.py b/moto/ec2/models/elastic_ip_addresses.py
index e1dbc7f2e..1e1d31ad2 100644
--- a/moto/ec2/models/elastic_ip_addresses.py
+++ b/moto/ec2/models/elastic_ip_addresses.py
@@ -2,7 +2,6 @@ from moto.core import CloudFormationModel
 from .core import TaggedEC2Resource
 from ..exceptions import (
     FilterNotImplementedError,
-    InvalidDomainError,
     InvalidAddressError,
     InvalidAllocationIdError,
     ResourceAlreadyAssociatedError,
@@ -113,7 +112,7 @@ class ElasticAddressBackend:
 
     def allocate_address(self, domain, address=None, tags=None):
         if domain not in ["standard", "vpc"]:
-            raise InvalidDomainError(domain)
+            domain = "vpc"
         if address:
             address = ElasticAddress(self, domain=domain, address=address, tags=tags)
         else:
diff --git a/moto/ec2/responses/elastic_ip_addresses.py b/moto/ec2/responses/elastic_ip_addresses.py
index eea5e2f6e..2deba6be8 100644
--- a/moto/ec2/responses/elastic_ip_addresses.py
+++ b/moto/ec2/responses/elastic_ip_addresses.py
@@ -4,7 +4,7 @@ from ._base_response import EC2BaseResponse
 
 class ElasticIPAddresses(EC2BaseResponse):
     def allocate_address(self):
-        domain = self._get_param("Domain", if_none="standard")
+        domain = self._get_param("Domain", if_none=None)
         reallocate_address = self._get_param("Address", if_none=None)
         tags = self._get_multi_param("TagSpecification")
         tags = add_tag_specification(tags)
diff --git a/tests/test_ec2/test_elastic_ip_addresses.py b/tests/test_ec2/test_elastic_ip_addresses.py
index 585f08ac3..0677d3a86 100644
--- a/tests/test_ec2/test_elastic_ip_addresses.py
+++ b/tests/test_ec2/test_elastic_ip_addresses.py
@@ -24,7 +24,7 @@ def test_eip_allocate_classic():
         "An error occurred (DryRunOperation) when calling the AllocateAddress operation: Request would have succeeded, but DryRun flag is set"
     )
 
-    standard = client.allocate_address()
+    standard = client.allocate_address(Domain="standard")
     standard.should.have.key("PublicIp")
     standard.should.have.key("Domain").equal("standard")
 
@@ -78,12 +78,22 @@ def test_eip_allocate_vpc():
     vpc.should.have.key("AllocationId")
     vpc.should.have.key("Domain").equal("vpc")
 
+    # Ensure that correct fallback is used for the optional attribute `Domain` contains an empty or invalid value
+    vpc2 = client.allocate_address(Domain="")
+    vpc3 = client.allocate_address(Domain="xyz")
+
+    vpc2.should.have.key("Domain").equal("vpc")
+    vpc3.should.have.key("Domain").equal("vpc")
+
     allocation_id = vpc["AllocationId"]
+    allocation_id2 = vpc["AllocationId"]
+    allocation_id3 = vpc["AllocationId"]
 
     all_addresses = client.describe_addresses()["Addresses"]
-    [a["AllocationId"] for a in all_addresses if "AllocationId" in a].should.contain(
-        allocation_id
-    )
+    allocation_ids = [a["AllocationId"] for a in all_addresses if "AllocationId" in a]
+    allocation_ids.should.contain(allocation_id)
+    allocation_ids.should.contain(allocation_id2)
+    allocation_ids.should.contain(allocation_id3)
 
     vpc = ec2.VpcAddress(allocation_id)
     vpc.release()
@@ -104,18 +114,6 @@ def test_specific_eip_allocate_vpc():
     vpc["PublicIp"].should.be.equal("127.38.43.222")
 
 
-@mock_ec2
-def test_eip_allocate_invalid_domain():
-    """Allocate EIP invalid domain"""
-    client = boto3.client("ec2", region_name="us-east-1")
-
-    with pytest.raises(ClientError) as ex:
-        client.allocate_address(Domain="bogus")
-    ex.value.response["ResponseMetadata"]["HTTPStatusCode"].should.equal(400)
-    ex.value.response["ResponseMetadata"]["RequestId"].shouldnt.equal(None)
-    ex.value.response["Error"]["Code"].should.equal("InvalidParameterValue")
-
-
 @mock_ec2
 def test_eip_associate_classic():
     """Associate/Disassociate EIP to classic instance"""