ec2: get attributes from launch template when starting instances

Co-authored-by: Claude <noreply@anthropic.com>

Author: nik-localstack

moto/ec2/models/instances.py

@@ -773,6 +773,29 @@ def run_instances(
         The KeyPair-parameter can be validated, to see if it is a known key-pair.
         Enable this validation by setting the environment variable `MOTO_ENABLE_KEYPAIR_VALIDATION=true`
         """
+        if kwargs.get("launch_template"):
+            tmpl = self._get_template_from_args(kwargs["launch_template"]).data
+
+            if user_data is None and (template_user_data := tmpl.get("UserData")):
+                user_data = template_user_data
+            if kwargs.get("is_instance_type_default") and (
+                template_instance_type := tmpl.get("InstanceType")
+            ):
+                kwargs["instance_type"] = template_instance_type
+                kwargs["is_instance_type_default"] = False
+            if not kwargs.get("key_name") and (
+                template_key_name := tmpl.get("KeyName")
+            ):
+                kwargs["key_name"] = template_key_name
+            if not kwargs.get("security_group_ids") and (
+                template_sg_ids := tmpl.get("SecurityGroupIds")
+            ):
+                kwargs["security_group_ids"] = template_sg_ids
+            if not security_group_names and (
+                template_sgs := tmpl.get("SecurityGroups")
+            ):
+                security_group_names = template_sgs
+
         location_type = "availability-zone" if kwargs.get("placement") else "region"
         default_region = "us-east-1"
         if settings.ENABLE_KEYPAIR_VALIDATION:

tests/test_ec2/test_instances.py

@@ -3158,15 +3158,28 @@ def _verify_instance_tags(
         assert tags[key] == value
 
 
-def _run_instance_from_template(ec2_client, template_id, version=None):
-    launch_template_spec = {"LaunchTemplateId": template_id}
+def _run_instance_from_template(
+    ec2_client,
+    template_id=None,
+    template_name=None,
+    version=None,
+    **instance_kwargs,
+):
+    launch_template_spec = {}
+    if template_id:
+        launch_template_spec["LaunchTemplateId"] = template_id
+    elif template_name:
+        launch_template_spec["LaunchTemplateName"] = template_name
+    else:
+        raise ValueError("Either template_id or template_name must be provided.")
     if version:
         launch_template_spec["Version"] = version
 
     instance = ec2_client.run_instances(
         MinCount=1,
         MaxCount=1,
         LaunchTemplate=launch_template_spec,
+        **instance_kwargs,
     )["Instances"][0]
     return instance
 
@@ -3334,3 +3347,201 @@ def test_create_instance_from_launch_template_latest_and_default_version(
     finally:
         # Clean up launch template
         ec2_client.delete_launch_template(LaunchTemplateId=template_id)
+
+
+_LT_USER_DATA_SCRIPT = b"#!/bin/bash\necho from-template"
+_LT_USER_DATA_B64 = base64.b64encode(_LT_USER_DATA_SCRIPT).decode()
+
+
+@ec2_aws_verified(
+    create_launch_template=True,
+    launch_template_data={"InstanceType": "t2.micro", "UserData": _LT_USER_DATA_B64},
+)
+@pytest.mark.aws_verified
+def test_run_instances__user_data_from_launch_template(
+    ec2_client=None, launch_template_name=None
+):
+    """UserData in a launch template is applied when not supplied in RunInstances."""
+    ami_id = _get_ami_id(ec2_client)
+    instance = _run_instance_from_template(
+        ec2_client, template_name=launch_template_name, ImageId=ami_id
+    )
+    instance_id = instance["InstanceId"]
+    try:
+        attr = ec2_client.describe_instance_attribute(
+            InstanceId=instance_id, Attribute="userData"
+        )
+        assert attr["UserData"]["Value"] == _LT_USER_DATA_B64
+    finally:
+        ec2_client.terminate_instances(InstanceIds=[instance_id])
+
+
+@ec2_aws_verified(
+    create_launch_template=True,
+    launch_template_data={"InstanceType": "t2.micro", "UserData": _LT_USER_DATA_B64},
+)
+@pytest.mark.aws_verified
+def test_run_instances__user_data_override_takes_priority(
+    ec2_client=None, launch_template_name=None
+):
+    """Explicit UserData in RunInstances overrides the launch template value."""
+    ami_id = _get_ami_id(ec2_client)
+    request_script = "#!/bin/bash\necho from-request"
+    expected_b64 = base64.b64encode(request_script.encode()).decode()
+
+    instance = _run_instance_from_template(
+        ec2_client,
+        template_name=launch_template_name,
+        ImageId=ami_id,
+        UserData=request_script,
+    )
+    instance_id = instance["InstanceId"]
+    try:
+        attr = ec2_client.describe_instance_attribute(
+            InstanceId=instance_id, Attribute="userData"
+        )
+        assert attr["UserData"]["Value"] == expected_b64
+    finally:
+        ec2_client.terminate_instances(InstanceIds=[instance_id])
+
+
+@ec2_aws_verified(
+    create_launch_template=True,
+    launch_template_data={"InstanceType": "t2.micro"},
+)
+@pytest.mark.aws_verified
+def test_run_instances__instance_type_from_launch_template(
+    ec2_client=None, launch_template_name=None
+):
+    """InstanceType in a launch template is applied when not supplied in RunInstances."""
+    ami_id = _get_ami_id(ec2_client)
+    instance = _run_instance_from_template(
+        ec2_client, template_name=launch_template_name, ImageId=ami_id
+    )
+    instance_id = instance["InstanceId"]
+    try:
+        assert instance["InstanceType"] == "t2.micro"
+        attr = ec2_client.describe_instance_attribute(
+            InstanceId=instance_id, Attribute="instanceType"
+        )
+        assert attr["InstanceType"]["Value"] == "t2.micro"
+        describe_instances = ec2_client.describe_instances(InstanceIds=[instance_id])
+        assert (
+            describe_instances["Reservations"][0]["Instances"][0]["InstanceType"]
+            == "t2.micro"
+        )
+    finally:
+        ec2_client.terminate_instances(InstanceIds=[instance_id])
+
+
+@ec2_aws_verified(
+    create_launch_template=True,
+    launch_template_data={"InstanceType": "t2.micro"},
+)
+@pytest.mark.aws_verified
+def test_run_instances__instance_type_override_takes_priority(
+    ec2_client=None, launch_template_name=None
+):
+    """Explicit InstanceType in RunInstances overrides the launch template value."""
+    ami_id = _get_ami_id(ec2_client)
+    resp = ec2_client.run_instances(
+        MinCount=1,
+        MaxCount=1,
+        ImageId=ami_id,
+        LaunchTemplate={"LaunchTemplateName": launch_template_name},
+        InstanceType="t2.small",
+    )
+    instance_id = resp["Instances"][0]["InstanceId"]
+    try:
+        assert resp["Instances"][0]["InstanceType"] == "t2.small"
+        attr = ec2_client.describe_instance_attribute(
+            InstanceId=instance_id, Attribute="instanceType"
+        )
+        assert attr["InstanceType"]["Value"] == "t2.small"
+        describe_instances = ec2_client.describe_instances(InstanceIds=[instance_id])
+        assert (
+            describe_instances["Reservations"][0]["Instances"][0]["InstanceType"]
+            == "t2.small"
+        )
+    finally:
+        ec2_client.terminate_instances(InstanceIds=[instance_id])
+
+
+@ec2_aws_verified()
+@pytest.mark.aws_verified
+def test_run_instances__key_name_from_launch_template(ec2_client=None):
+    """KeyName in a launch template is applied when not supplied in RunInstances."""
+    ami_id = _get_ami_id(ec2_client)
+    key_name = f"test-key-{str(uuid4())[0:8]}"
+    lt_name = str(uuid4())
+    ec2_client.create_key_pair(KeyName=key_name)
+    ec2_client.create_launch_template(
+        LaunchTemplateName=lt_name,
+        LaunchTemplateData={"InstanceType": "t2.micro", "KeyName": key_name},
+    )
+    instance = _run_instance_from_template(
+        ec2_client, template_name=lt_name, ImageId=ami_id
+    )
+    instance_id = instance["InstanceId"]
+    try:
+        assert instance["KeyName"] == key_name
+        describe_instances = ec2_client.describe_instances(InstanceIds=[instance_id])
+        assert (
+            describe_instances["Reservations"][0]["Instances"][0]["KeyName"] == key_name
+        )
+    finally:
+        ec2_client.terminate_instances(InstanceIds=[instance_id])
+        ec2_client.delete_launch_template(LaunchTemplateName=lt_name)
+        ec2_client.delete_key_pair(KeyName=key_name)
+
+
+@ec2_aws_verified()
+@pytest.mark.aws_verified
+def test_run_instances__security_group_ids_from_launch_template(ec2_client=None):
+    """SecurityGroupIds in a launch template are applied when not supplied in RunInstances."""
+    ami_id = _get_ami_id(ec2_client)
+    vpc_id = ec2_client.create_vpc(CidrBlock="10.0.0.0/16")["Vpc"]["VpcId"]
+    subnet_id = ec2_client.create_subnet(
+        VpcId=vpc_id,
+        CidrBlock="10.0.1.0/24",
+        AvailabilityZone=ec2_client.meta.region_name + "a",
+    )["Subnet"]["SubnetId"]
+    sg_id = ec2_client.create_security_group(
+        GroupName=f"test-sg-{str(uuid4())[0:6]}",
+        Description="test",
+        VpcId=vpc_id,
+    )["GroupId"]
+    lt_name = str(uuid4())
+    ec2_client.create_launch_template(
+        LaunchTemplateName=lt_name,
+        LaunchTemplateData={
+            "InstanceType": "t2.micro",
+            "SecurityGroupIds": [sg_id],
+        },
+    )
+    instance = _run_instance_from_template(
+        ec2_client, template_name=lt_name, ImageId=ami_id, SubnetId=subnet_id
+    )
+    instance_id = instance["InstanceId"]
+    try:
+        instance_sg_ids = [g["GroupId"] for g in instance["SecurityGroups"]]
+        assert sg_id in instance_sg_ids
+        attr = ec2_client.describe_instance_attribute(
+            InstanceId=instance_id, Attribute="groupSet"
+        )
+        attr_sg_ids = [g["GroupId"] for g in attr["Groups"]]
+        assert sg_id in attr_sg_ids
+        describe_instances = ec2_client.describe_instances(InstanceIds=[instance_id])
+        instance_sg_ids = [
+            g["GroupId"]
+            for g in describe_instances["Reservations"][0]["Instances"][0][
+                "SecurityGroups"
+            ]
+        ]
+        assert sg_id in instance_sg_ids
+    finally:
+        ec2_client.terminate_instances(InstanceIds=[instance_id])
+        ec2_client.delete_launch_template(LaunchTemplateName=lt_name)
+        ec2_client.delete_security_group(GroupId=sg_id)
+        ec2_client.delete_subnet(SubnetId=subnet_id)
+        ec2_client.delete_vpc(VpcId=vpc_id)