Merge branch 'master' into change/add_data_wrangler_processor

Author: ajaykarpur

src/sagemaker/workflow/_repack_model.py

@@ -19,6 +19,13 @@
 import tarfile
 import tempfile
 
+# Repack Model
+# The following script is run via a training job which takes an existing model and a custom
+# entry point script as arguments. The script creates a new model archive with the custom
+# entry point in the "code" directory along with the existing model.  Subsequently, when the model
+# is unpacked for inference, the custom entry point will be used.
+# Reference: https://docs.aws.amazon.com/sagemaker/latest/dg/amazon-sagemaker-toolkits.html
+
 # distutils.dir_util.copy_tree works way better than the half-baked
 # shutil.copytree which bombs on previously existing target dirs...
 # alas ... https://bugs.python.org/issue10948
@@ -33,17 +40,28 @@
     parser.add_argument("--model_archive", type=str, default="model.tar.gz")
     args = parser.parse_args()
 
+    # the data directory contains a model archive generated by a previous training job
     data_directory = "/opt/ml/input/data/training"
     model_path = os.path.join(data_directory, args.model_archive)
 
+    # create a temporary directory
     with tempfile.TemporaryDirectory() as tmp:
         local_path = os.path.join(tmp, "local.tar.gz")
+        # copy the previous training job's model archive to the temporary directory
         shutil.copy2(model_path, local_path)
         src_dir = os.path.join(tmp, "src")
+        # create the "code" directory which will contain the inference script
+        os.makedirs(os.path.join(src_dir, "code"))
+        # extract the contents of the previous training job's model archive to the "src"
+        # directory of this training job
         with tarfile.open(name=local_path, mode="r:gz") as tf:
             tf.extractall(path=src_dir)
 
+        # generate a path to the custom inference script
         entry_point = os.path.join("/opt/ml/code", args.inference_script)
-        shutil.copy2(entry_point, os.path.join(src_dir, args.inference_script))
+        # copy the custom inference script to the "src" dir
+        shutil.copy2(entry_point, os.path.join(src_dir, "code", args.inference_script))
 
+        # copy the "src" dir, which includes the previous training job's model and the
+        # custom inference script, to the output of this training job
         copy_tree(src_dir, "/opt/ml/model")