Make batch.utils.lowercase_first_key() recursive (#3124)

* Make batch.utils.lowercase_first_key() recursive

* Reformat using black

* Add test of recursive lowercase_first_key()

* Fix typo in ttest_batch/test_cloud_formation.py

moto/batch/utils.py

@@ -21,6 +21,14 @@ def lowercase_first_key(some_dict):
     new_dict = {}
     for key, value in some_dict.items():
         new_key = key[0].lower() + key[1:]
-        new_dict[new_key] = value
+        try:
+            if isinstance(value, dict):
+                new_dict[new_key] = lowercase_first_key(value)
+            elif all([isinstance(v, dict) for v in value]):
+                new_dict[new_key] = [lowercase_first_key(v) for v in value]
+            else:
+                new_dict[new_key] = value
+        except TypeError:
+            new_dict[new_key] = value
 
     return new_dict

tests/test_batch/test_cloudformation.py

@@ -234,6 +234,7 @@ def test_create_job_def_cf():
                         "Vcpus": 2,
                         "Memory": 2000,
                         "Command": ["echo", "Hello world"],
+                        "LinuxParameters": {"Devices": [{"HostPath": "test-path"}]},
                     },
                     "RetryStrategy": {"Attempts": 1},
                 },
@@ -262,3 +263,17 @@ def test_create_job_def_cf():
     job_def_resource["PhysicalResourceId"].startswith("arn:aws:batch:")
     job_def_resource["PhysicalResourceId"].should.contain("test_stack-JobDef")
     job_def_resource["PhysicalResourceId"].should.contain("job-definition/")
+
+    # Test the linux parameter device host path
+    # This ensures that batch is parsing the parameter dictionaries
+    # correctly by recursively converting the first character of all
+    # dict keys to lowercase.
+    batch_conn = boto3.client("batch", DEFAULT_REGION)
+    response = batch_conn.describe_job_definitions(
+        jobDefinitions=[job_def_resource["PhysicalResourceId"]]
+    )
+    job_def_linux_device_host_path = response.get("jobDefinitions")[0][
+        "containerProperties"
+    ]["linuxParameters"]["devices"][0]["hostPath"]
+
+    job_def_linux_device_host_path.should.equal("test-path")