From 08c65a9a3c0e9ff9bf225720349b48ac685ebebe Mon Sep 17 00:00:00 2001
From: Viren Nadkarni <viren.nadkarni@gmail.com>
Date: Fri, 2 Dec 2022 18:47:06 +0530
Subject: [PATCH] EC2: fix launch template names not being reusable after
 delete (#5726)

---
 moto/ec2/models/launch_templates.py       | 11 +++++-
 tests/test_ec2/test_ec2_cloudformation.py | 10 +++--
 tests/test_ec2/test_launch_templates.py   | 45 ++++++++++++++++++++---
 3 files changed, 55 insertions(+), 11 deletions(-)

diff --git a/moto/ec2/models/launch_templates.py b/moto/ec2/models/launch_templates.py
index 69ecf9def..488813043 100644
--- a/moto/ec2/models/launch_templates.py
+++ b/moto/ec2/models/launch_templates.py
@@ -12,6 +12,7 @@ from ..exceptions import (
     InvalidLaunchTemplateNameAlreadyExistsError,
     InvalidLaunchTemplateNameNotFoundError,
     InvalidLaunchTemplateNameNotFoundWithNameError,
+    MissingParameterError,
 )
 
 
@@ -189,8 +190,14 @@ class LaunchTemplateBackend:
 
     def delete_launch_template(self, name, tid):
         if name:
-            tid = self.launch_template_name_to_ids[name]
-        return self.launch_templates.pop(tid)
+            tid = self.launch_template_name_to_ids.get(name)
+        if tid is None:
+            raise MissingParameterError("launch template ID or launch template name")
+        if tid not in self.launch_templates:
+            raise InvalidLaunchTemplateNameNotFoundError()
+        template = self.launch_templates.pop(tid)
+        self.launch_template_name_to_ids.pop(template.name, None)
+        return template
 
     def describe_launch_templates(
         self, template_names=None, template_ids=None, filters=None
diff --git a/tests/test_ec2/test_ec2_cloudformation.py b/tests/test_ec2/test_ec2_cloudformation.py
index a3120f663..7b29f6734 100644
--- a/tests/test_ec2/test_ec2_cloudformation.py
+++ b/tests/test_ec2/test_ec2_cloudformation.py
@@ -938,6 +938,10 @@ def test_launch_template_delete():
 
     cf.delete_stack(StackName=stack_name)
 
-    ec2.describe_launch_templates(LaunchTemplateNames=[launch_template_name])[
-        "LaunchTemplates"
-    ].should.have.length_of(0)
+    with pytest.raises(ClientError) as exc:
+        ec2.describe_launch_templates(LaunchTemplateNames=[launch_template_name])
+    err = exc.value.response["Error"]
+    err.should.have.key("Code").equals("InvalidLaunchTemplateName.NotFoundException")
+    err.should.have.key("Message").equals(
+        "At least one of the launch templates specified in the request does not exist."
+    )
diff --git a/tests/test_ec2/test_launch_templates.py b/tests/test_ec2/test_launch_templates.py
index f6142b0a3..1133ee229 100644
--- a/tests/test_ec2/test_launch_templates.py
+++ b/tests/test_ec2/test_launch_templates.py
@@ -482,9 +482,21 @@ def test_delete_launch_template__by_name():
 
     cli.delete_launch_template(LaunchTemplateName=template_name)
 
-    cli.describe_launch_templates(LaunchTemplateNames=[template_name])[
-        "LaunchTemplates"
-    ].should.have.length_of(0)
+    with pytest.raises(ClientError) as exc:
+        cli.describe_launch_templates(LaunchTemplateNames=[template_name])[
+            "LaunchTemplates"
+        ]
+    err = exc.value.response["Error"]
+    err.should.have.key("Code").equals("InvalidLaunchTemplateName.NotFoundException")
+    err.should.have.key("Message").equals(
+        "At least one of the launch templates specified in the request does not exist."
+    )
+
+    # Ensure deleted template name can be reused
+    cli.create_launch_template(
+        LaunchTemplateName=template_name,
+        LaunchTemplateData={"ImageId": "ami-abc123"},
+    )
 
 
 @mock_ec2
@@ -492,6 +504,15 @@ def test_delete_launch_template__by_id():
     cli = boto3.client("ec2", region_name="us-east-1")
 
     template_name = str(uuid4())
+
+    with pytest.raises(ClientError) as exc:
+        cli.delete_launch_template()
+    err = exc.value.response["Error"]
+    err.should.have.key("Code").equals("MissingParameter")
+    err.should.have.key("Message").equals(
+        "The request must contain the parameter launch template ID or launch template name"
+    )
+
     template_id = cli.create_launch_template(
         LaunchTemplateName=template_name, LaunchTemplateData={"ImageId": "ami-abc123"}
     )["LaunchTemplate"]["LaunchTemplateId"]
@@ -502,9 +523,21 @@ def test_delete_launch_template__by_id():
 
     cli.delete_launch_template(LaunchTemplateId=template_id)
 
-    cli.describe_launch_templates(LaunchTemplateNames=[template_name])[
-        "LaunchTemplates"
-    ].should.have.length_of(0)
+    with pytest.raises(ClientError) as exc:
+        cli.describe_launch_templates(LaunchTemplateNames=[template_name])[
+            "LaunchTemplates"
+        ]
+    err = exc.value.response["Error"]
+    err.should.have.key("Code").equals("InvalidLaunchTemplateName.NotFoundException")
+    err.should.have.key("Message").equals(
+        "At least one of the launch templates specified in the request does not exist."
+    )
+
+    # Ensure deleted template name can be reused
+    cli.create_launch_template(
+        LaunchTemplateName=template_name,
+        LaunchTemplateData={"ImageId": "ami-abc123"},
+    )
 
 
 def retrieve_all_templates(client, filters=[]):  # pylint: disable=W0102