added image specific io functions

shared/data_store/put_image.py

@@ -0,0 +1,44 @@
+"""Definition of put_image function."""
+
+import logging
+import os
+from hashlib import md5
+from io import BytesIO
+
+from minio import Minio
+from PIL import Image
+
+
+def put_image(
+    client: Minio,
+    image: Image.Image,
+) -> str:
+    """Put image in image subfolder in bucket in Minio and return MD5 checksum
+    used as object name."""
+    assert isinstance(client, Minio)
+    assert isinstance(image, Image.Image)
+    bucket_name = os.getenv('MINIO_BUCKET_NAME', default=None)
+    assert isinstance(bucket_name, str)
+    subfolder = 'images'
+    # save image to buffer
+    buffer = BytesIO()
+    image.save(buffer, 'png')
+    # get md5 of image
+    checksum = md5(buffer.getbuffer()).hexdigest()
+    # prepare for saving
+    num_bytes = buffer.tell()
+    buffer.seek(0)
+    # send data to bucket
+    object_name = f'{subfolder}/{checksum}'
+    try:
+        client.put_object(
+            bucket_name=bucket_name,
+            object_name=object_name,
+            length=num_bytes,
+            data=buffer,
+        )
+    except Exception as exc:
+        logging.error('failed saving data to MinIO')
+        raise exc
+    logging.debug('saved data to %s', object_name)
+    return checksum