From 3ae4c23c236841bf44d0f6374dbab35e5891909a Mon Sep 17 00:00:00 2001
From: Sahil Shah <53784576+sahilshah6196@users.noreply.github.com>
Date: Thu, 1 Jul 2021 11:25:40 -0400
Subject: [PATCH] Transform certificates in listener in expected XML (#4049)

---
 moto/elbv2/models.py           | 57 +++++++++++++++-------------------
 tests/test_elbv2/test_elbv2.py | 16 +++++-----
 2 files changed, 34 insertions(+), 39 deletions(-)

diff --git a/moto/elbv2/models.py b/moto/elbv2/models.py
index 178dc72b4..3033680ec 100644
--- a/moto/elbv2/models.py
+++ b/moto/elbv2/models.py
@@ -265,6 +265,7 @@ class FakeListener(CloudFormationModel):
         certificates = properties.get("Certificates")
 
         default_actions = elbv2_backend.convert_and_validate_properties(properties)
+        certificates = elbv2_backend.convert_and_validate_certificates(certificates)
         listener = elbv2_backend.create_listener(
             load_balancer_arn, protocol, port, ssl_policy, certificates, default_actions
         )
@@ -283,6 +284,7 @@ class FakeListener(CloudFormationModel):
         certificates = properties.get("Certificates")
 
         default_actions = elbv2_backend.convert_and_validate_properties(properties)
+        certificates = elbv2_backend.convert_and_validate_certificates(certificates)
         listener = elbv2_backend.modify_listener(
             original_resource.arn,
             port,
@@ -833,6 +835,14 @@ Member must satisfy regular expression pattern: {}".format(
         self.target_groups[target_group.arn] = target_group
         return target_group
 
+    def convert_and_validate_certificates(self, certificates):
+
+        # transform default certificate to conform with the rest of the code and XML templates
+        for cert in certificates or []:
+            cert["certificate_arn"] = cert["CertificateArn"]
+
+        return certificates
+
     def convert_and_validate_properties(self, properties):
 
         # transform default actions to confirm with the rest of the code and XML templates
@@ -1308,41 +1318,24 @@ Member must satisfy regular expression pattern: {}".format(
 
             # HTTPS checks
             if protocol == "HTTPS":
-                # HTTPS
-
-                # Might already be HTTPS so may not provide certs
-                if certificates is None and listener.protocol != "HTTPS":
-                    raise RESTError(
-                        "InvalidConfigurationRequest",
-                        "Certificates must be provided for HTTPS",
-                    )
-
                 # Check certificates exist
-                if certificates is not None:
-                    default_cert = None
-                    all_certs = set()  # for SNI
-                    for cert in certificates:
-                        if cert["is_default"] == "true":
-                            default_cert = cert["certificate_arn"]
-                        try:
-                            self.acm_backend.get_certificate(cert["certificate_arn"])
-                        except Exception:
-                            raise RESTError(
-                                "CertificateNotFound",
-                                "Certificate {0} not found".format(
-                                    cert["certificate_arn"]
-                                ),
-                            )
-
-                        all_certs.add(cert["certificate_arn"])
-
-                    if default_cert is None:
+                if certificates:
+                    default_cert = certificates[0]
+                    default_cert_arn = default_cert["certificate_arn"]
+                    try:
+                        self.acm_backend.get_certificate(default_cert_arn)
+                    except Exception:
                         raise RESTError(
-                            "InvalidConfigurationRequest", "No default certificate"
+                            "CertificateNotFound",
+                            "Certificate {0} not found".format(default_cert_arn),
                         )
-
-                    listener.certificate = default_cert
-                    listener.certificates = list(all_certs)
+                    listener.certificate = default_cert_arn
+                    listener.certificates = certificates
+                else:
+                    raise RESTError(
+                        "CertificateWereNotPassed",
+                        "You must provide a list containing exactly one certificate if the listener protocol is HTTPS.",
+                    )
 
             listener.protocol = protocol
 
diff --git a/tests/test_elbv2/test_elbv2.py b/tests/test_elbv2/test_elbv2.py
index 2c3e53c19..1f1d8a74c 100644
--- a/tests/test_elbv2/test_elbv2.py
+++ b/tests/test_elbv2/test_elbv2.py
@@ -1767,10 +1767,7 @@ def test_modify_listener_http_to_https():
         Port=443,
         Protocol="HTTPS",
         SslPolicy="ELBSecurityPolicy-TLS-1-2-2017-01",
-        Certificates=[
-            {"CertificateArn": google_arn, "IsDefault": False},
-            {"CertificateArn": yahoo_arn, "IsDefault": True},
-        ],
+        Certificates=[{"CertificateArn": yahoo_arn,},],
         DefaultActions=[{"Type": "forward", "TargetGroupArn": target_group_arn}],
     )
     response["Listeners"][0]["Port"].should.equal(443)
@@ -1778,7 +1775,7 @@ def test_modify_listener_http_to_https():
     response["Listeners"][0]["SslPolicy"].should.equal(
         "ELBSecurityPolicy-TLS-1-2-2017-01"
     )
-    len(response["Listeners"][0]["Certificates"]).should.equal(2)
+    len(response["Listeners"][0]["Certificates"]).should.equal(1)
 
     # Check default cert, can't do this in server mode
     if os.environ.get("TEST_SERVER_MODE", "false").lower() == "false":
@@ -1790,15 +1787,20 @@ def test_modify_listener_http_to_https():
         listener.certificate.should.equal(yahoo_arn)
 
     # No default cert
-    with pytest.raises(ClientError):
+    with pytest.raises(ClientError) as ex:
         client.modify_listener(
             ListenerArn=listener_arn,
             Port=443,
             Protocol="HTTPS",
             SslPolicy="ELBSecurityPolicy-TLS-1-2-2017-01",
-            Certificates=[{"CertificateArn": google_arn, "IsDefault": False}],
+            Certificates=[],
             DefaultActions=[{"Type": "forward", "TargetGroupArn": target_group_arn}],
         )
+    err = ex.value.response["Error"]
+    err["Code"].should.equal("CertificateWereNotPassed")
+    err["Message"].should.equal(
+        "You must provide a list containing exactly one certificate if the listener protocol is HTTPS."
+    )
 
     # Bad cert
     with pytest.raises(ClientError):