From 12188733b73fe5511692f05f0a1ed586a2fa7777 Mon Sep 17 00:00:00 2001
From: zane <zane.williamson@gmail.com>
Date: Thu, 10 May 2018 23:39:19 -0700
Subject: [PATCH] adding Address reallocate capability for EIP

---
 moto/ec2/models.py                          | 15 ++++++++++-----
 moto/ec2/responses/elastic_ip_addresses.py  |  7 ++++++-
 tests/test_ec2/test_elastic_ip_addresses.py | 11 +++++++++++
 3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/moto/ec2/models.py b/moto/ec2/models.py
index 31bfb4839..674e0bddb 100755
--- a/moto/ec2/models.py
+++ b/moto/ec2/models.py
@@ -3159,8 +3159,11 @@ class SpotFleetBackend(object):
 
 
 class ElasticAddress(object):
-    def __init__(self, domain):
-        self.public_ip = random_ip()
+    def __init__(self, domain, address=None):
+        if address:
+            self.public_ip = address
+        else:
+            self.public_ip = random_ip()
         self.allocation_id = random_eip_allocation_id() if domain == "vpc" else None
         self.domain = domain
         self.instance = None
@@ -3222,11 +3225,13 @@ class ElasticAddressBackend(object):
         self.addresses = []
         super(ElasticAddressBackend, self).__init__()
 
-    def allocate_address(self, domain):
+    def allocate_address(self, domain, address=None):
         if domain not in ['standard', 'vpc']:
             raise InvalidDomainError(domain)
-
-        address = ElasticAddress(domain)
+        if address:
+            address = ElasticAddress(domain, address)
+        else:
+            address = ElasticAddress(domain)
         self.addresses.append(address)
         return address
 
diff --git a/moto/ec2/responses/elastic_ip_addresses.py b/moto/ec2/responses/elastic_ip_addresses.py
index 11c1d9c1f..6e1c9fe38 100644
--- a/moto/ec2/responses/elastic_ip_addresses.py
+++ b/moto/ec2/responses/elastic_ip_addresses.py
@@ -7,8 +7,13 @@ class ElasticIPAddresses(BaseResponse):
 
     def allocate_address(self):
         domain = self._get_param('Domain', if_none='standard')
+        reallocate_address = self._get_param('Address', if_none=None)
         if self.is_not_dryrun('AllocateAddress'):
-            address = self.ec2_backend.allocate_address(domain)
+            if reallocate_address:
+                address = self.ec2_backend.allocate_address(
+                    domain, address=reallocate_address)
+            else:
+                address = self.ec2_backend.allocate_address(domain)
             template = self.response_template(ALLOCATE_ADDRESS_RESPONSE)
             return template.render(address=address)
 
diff --git a/tests/test_ec2/test_elastic_ip_addresses.py b/tests/test_ec2/test_elastic_ip_addresses.py
index 709bdc33b..ca6637b18 100644
--- a/tests/test_ec2/test_elastic_ip_addresses.py
+++ b/tests/test_ec2/test_elastic_ip_addresses.py
@@ -62,6 +62,17 @@ def test_eip_allocate_vpc():
     logging.debug("vpc alloc_id:".format(vpc.allocation_id))
     vpc.release()
 
+@mock_ec2
+def test_specific_eip_allocate_vpc():
+    """Allocate VPC EIP with specific address"""
+    service = boto3.resource('ec2', region_name='us-west-1')
+    client = boto3.client('ec2', region_name='us-west-1')
+
+    vpc = client.allocate_address(Domain="vpc", Address="127.38.43.222")
+    vpc['Domain'].should.be.equal("vpc")
+    vpc['PublicIp'].should.be.equal("127.38.43.222")
+    logging.debug("vpc alloc_id:".format(vpc['AllocationId']))
+
 
 @mock_ec2_deprecated
 def test_eip_allocate_invalid_domain():