From 0b4889ad377ac773659735a26fd9779d631d7db6 Mon Sep 17 00:00:00 2001
From: Pepe Fagoaga <pepe@verica.io>
Date: Wed, 16 Aug 2023 23:55:24 +0200
Subject: [PATCH] feat(ec2): Add Instance Monitoring attribute (#6678)

---
 moto/ec2/models/instances.py     |  1 +
 moto/ec2/responses/instances.py  |  7 +++++--
 tests/test_ec2/test_instances.py | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/moto/ec2/models/instances.py b/moto/ec2/models/instances.py
index 19a2dac0b..8463ed9c3 100644
--- a/moto/ec2/models/instances.py
+++ b/moto/ec2/models/instances.py
@@ -120,6 +120,7 @@ class Instance(TaggedEC2Resource, BotoInstance, CloudFormationModel):
         in_ec2_classic = not bool(self.subnet_id)
         self.key_name = kwargs.get("key_name")
         self.ebs_optimized = kwargs.get("ebs_optimized", False)
+        self.monitoring_state = kwargs.get("monitoring_state", "disabled")
         self.source_dest_check = "true"
         self.launch_time = utc_date_and_time()
         self.ami_launch_index = kwargs.get("ami_launch_index", 0)
diff --git a/moto/ec2/responses/instances.py b/moto/ec2/responses/instances.py
index e1d2e0bcf..c1ec8fc92 100644
--- a/moto/ec2/responses/instances.py
+++ b/moto/ec2/responses/instances.py
@@ -84,6 +84,9 @@ class InstanceResponse(EC2BaseResponse):
             or None,
             "iam_instance_profile_arn": self._get_param("IamInstanceProfile.Arn")
             or None,
+            "monitoring_state": "enabled"
+            if self._get_param("Monitoring.Enabled") == "true"
+            else "disabled",
         }
         if len(kwargs["nics"]) and kwargs["subnet_id"]:
             raise InvalidParameterCombination(
@@ -472,7 +475,7 @@ EC2_RUN_INSTANCES = """<RunInstancesResponse xmlns="http://ec2.amazonaws.com/doc
             <tenancy>default</tenancy>
           </placement>
           <monitoring>
-            <state>enabled</state>
+            <state> {{ instance.monitoring_state }} </state>
           </monitoring>
           {% if instance.subnet_id %}
             <subnetId>{{ instance.subnet_id }}</subnetId>
@@ -632,7 +635,7 @@ EC2_DESCRIBE_INSTANCES = """<DescribeInstancesResponse xmlns="http://ec2.amazona
                     <platform>{{ instance.platform }}</platform>
                     {% endif %}
                     <monitoring>
-                      <state>disabled</state>
+                      <state>{{ instance.monitoring_state }}</state>
                     </monitoring>
                     {% if instance.subnet_id %}
                       <subnetId>{{ instance.subnet_id }}</subnetId>
diff --git a/tests/test_ec2/test_instances.py b/tests/test_ec2/test_instances.py
index 919630cfd..b45d52d89 100644
--- a/tests/test_ec2/test_instances.py
+++ b/tests/test_ec2/test_instances.py
@@ -2664,3 +2664,35 @@ def test_run_multiple_instances_with_single_nic_template():
     instance_1_ip = enis[1]["PrivateIpAddresses"][0]["PrivateIpAddress"]
 
     assert instance_0_ip != instance_1_ip
+
+
+@mock_ec2
+def test_describe_instance_without_enhanced_monitoring():
+    conn = boto3.client("ec2", region_name="us-west-1")
+
+    instance = conn.run_instances(
+        ImageId=EXAMPLE_AMI_ID, MinCount=1, MaxCount=1, Monitoring={"Enabled": True}
+    )
+    assert instance["Instances"][0]["Monitoring"] == {"State": "enabled"}
+
+    result = conn.describe_instances(
+        InstanceIds=[instance["Instances"][0]["InstanceId"]]
+    )["Reservations"][0]["Instances"]
+
+    assert result[0]["Monitoring"] == {"State": "enabled"}
+
+
+@mock_ec2
+def test_describe_instance_with_enhanced_monitoring():
+    conn = boto3.client("ec2", region_name="us-west-1")
+
+    instance = conn.run_instances(
+        ImageId=EXAMPLE_AMI_ID, MinCount=1, MaxCount=1, Monitoring={"Enabled": False}
+    )
+    assert instance["Instances"][0]["Monitoring"] == {"State": "disabled"}
+
+    result = conn.describe_instances(
+        InstanceIds=[instance["Instances"][0]["InstanceId"]]
+    )["Reservations"][0]["Instances"]
+
+    assert result[0]["Monitoring"] == {"State": "disabled"}