Fix custom amis import

moto/ec2/models/amis.py

@@ -154,17 +154,18 @@ def _load_amis(self):
             # owner_alias is required for terraform owner filters
             ami["owner_alias"] = "amazon"
             self.amis[ami_id] = Ami(self, **ami)
-        try:
-            latest_amis = load_resource(
-                __name__, f"../resources/latest_amis/{self.region_name}.json"
-            )
-            for ami in latest_amis:
-                ami_id = ami["ami_id"]
-                ami["owner_alias"] = "amazon"
-                self.amis[ami_id] = Ami(self, **ami)
-        except FileNotFoundError:
-            # Will error on unknown (new) regions - just return an empty list here
-            pass
+        if "MOTO_AMIS_PATH" not in environ:
+            try:
+                latest_amis = load_resource(
+                    __name__, f"../resources/latest_amis/{self.region_name}.json"
+                )
+                for ami in latest_amis:
+                    ami_id = ami["ami_id"]
+                    ami["owner_alias"] = "amazon"
+                    self.amis[ami_id] = Ami(self, **ami)
+            except FileNotFoundError:
+                # Will error on unknown (new) regions - just return an empty list here
+                pass
 
     def create_image(
         self,

tests/test_special_cases/test_custom_amis.py

@@ -0,0 +1,69 @@
+"""
+This test lives on its own as it requires moto to be imported after
+setting of MOTO_AMIS_PATH env var, as per ec2 models documentation
+"""
+import boto3
+import json
+import os
+import importlib
+from unittest import SkipTest, TestCase
+from pathlib import Path
+
+import moto
+from moto import settings, mock_ec2
+from moto.core import DEFAULT_ACCOUNT_ID
+from moto.ec2.models import ec2_backends
+
+
+@mock_ec2
+class TestEC2CustomAMIs(TestCase):
+    def setup_amis(self):
+        test_ami_path = Path(__file__).parent / "test_ami.json"
+        test_ami = [
+            {
+                "ami_id": "ami-760aaa0f760aaa0fe",
+                "name": "infra-eks-20211110080547-bionic",
+                "description": "An AMI",
+                "owner_id": "123456789012",
+                "public": False,
+                "virtualization_type": "hvm",
+                "architecture": "x86_64",
+                "state": "available",
+                "platform": None,
+                "image_type": "machine",
+                "hypervisor": "xen",
+                "root_device_name": "/dev/sda1",
+                "root_device_type": "ebs",
+                "sriov": "simple",
+                "creation_date": "2021-11-10T08:13:01.000Z",
+            }
+        ]
+        with test_ami_path.open("w") as fp:
+            json.dump(test_ami, fp)
+
+        return test_ami_path
+
+    def setUp(self) -> None:
+        if settings.TEST_SERVER_MODE:
+            raise SkipTest("Only test status code in non-ServerMode")
+        self.test_ami_path = self.setup_amis()
+        os.environ["MOTO_AMIS_PATH"] = str(self.test_ami_path)
+
+        # Reload the backend, and remove any existing AMIs
+        importlib.reload(moto.ec2.models.amis)
+        ec2_backends[DEFAULT_ACCOUNT_ID].reset()
+
+    def tearDown(self) -> None:
+        os.remove(self.test_ami_path)
+        del os.environ["MOTO_AMIS_PATH"]
+
+        # Reload the backend, and remove our custom AMI
+        importlib.reload(moto.ec2.models.amis)
+        ec2_backends[DEFAULT_ACCOUNT_ID].reset()
+
+    def test_custom_amis_with_MOTO_AMIS_PATH(self):
+        ec2_client = boto3.client("ec2", region_name="us-east-1")
+
+        # Now reload our images with only the custom AMIs loaded
+        images = ec2_client.describe_images()["Images"]
+        assert len(images) == 1