Lowercase container hostnames (aws#559)

* Change hostnames to lowercase

Author: mvsusp

CHANGELOG.rst

@@ -5,6 +5,7 @@ CHANGELOG
 1.16.3.dev
 ==========
 
+* bug-fix: Local Mode: Allow support for SSH in local mode 
 * bug-fix: Append retry id to default Airflow job name to avoid name collisions in retry
 * bug-fix: Local Mode: No longer requires s3 permissions to run local entry point file
 * bug-fix: Local Mode: Move dependency on sagemaker_s3_output from rl.estimator to model

src/sagemaker/local/image.py

@@ -79,7 +79,7 @@ def __init__(self, instance_type, instance_count, image, sagemaker_session=None)
         self.image = image
         # Since we are using a single docker network, Generate a random suffix to attach to the container names.
         #  This way multiple jobs can run in parallel.
-        suffix = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(5))
+        suffix = ''.join(random.choice(string.ascii_lowercase + string.digits) for _ in range(5))
         self.hosts = ['{}-{}-{}'.format(CONTAINER_PREFIX, i, suffix) for i in range(1, self.instance_count + 1)]
         self.container_root = None
         self.container = None

tests/unit/test_image.py

@@ -86,6 +86,23 @@ def sagemaker_session():
     return sms
 
 
+def test_sagemaker_container_hosts_should_have_lowercase_names():
+    random.seed(a=42)
+
+    def assert_all_lowercase(hosts):
+        for host in hosts:
+            assert host.lower() == host
+
+    sagemaker_container = _SageMakerContainer('local', 2, 'my-image', sagemaker_session=Mock())
+    assert_all_lowercase(sagemaker_container.hosts)
+
+    sagemaker_container = _SageMakerContainer('local', 10, 'my-image', sagemaker_session=Mock())
+    assert_all_lowercase(sagemaker_container.hosts)
+
+    sagemaker_container = _SageMakerContainer('local', 1, 'my-image', sagemaker_session=Mock())
+    assert_all_lowercase(sagemaker_container.hosts)
+
+
 @patch('sagemaker.local.local_session.LocalSession')
 def test_write_config_file(LocalSession, tmpdir):
     sagemaker_container = _SageMakerContainer('local', 2, 'my-image')