fixes #384 (#415)

* fixes #384

adlfs/spec.py

@@ -159,7 +159,12 @@ class AzureBlobFileSystem(AsyncFileSystem):
     version_aware : bool (False)
         Whether to support blob versioning.  If enable this will require the
         user to have the necessary permissions for dealing with versioned blobs.
-
+    assume_container_exists: Optional[bool] (None)
+        Set this to true to not check for existance of containers at all, assuming they exist.
+        None (default) means to warn in case of a failure when checking for existance of a container
+        False throws if retrieving container properties fails, which might happen if your
+        authentication is only valid at the storage container level, and not the
+        storage account level.
     Pass on to fsspec:
 
     skip_instance_cache:  to control reuse of instances
@@ -221,6 +226,7 @@ def __init__(
         default_fill_cache: bool = True,
         default_cache_type: str = "bytes",
         version_aware: bool = False,
+        assume_container_exists: Optional[bool] = None,
         **kwargs,
     ):
         super_kwargs = {
@@ -245,6 +251,7 @@ def __init__(
         self.location_mode = location_mode
         self.credential = credential
         self.request_session = request_session
+        self.assume_container_exists = assume_container_exists
         if socket_timeout is not _SOCKET_TIMEOUT_DEFAULT:
             warnings.warn(
                 "socket_timeout is deprecated and has no effect.", FutureWarning
@@ -1100,6 +1107,8 @@ async def _async_walk(self, path: str, maxdepth=None, **kwargs):
                 yield path, dirs, files
 
     async def _container_exists(self, container_name):
+        if self.assume_container_exists:
+            return True
         try:
             async with self.service_client.get_container_client(
                 container_name
@@ -1108,9 +1117,15 @@ async def _container_exists(self, container_name):
         except ResourceNotFoundError:
             return False
         except Exception as e:
-            raise ValueError(
-                f"Failed to fetch container properties for {container_name} for {e}"
-            ) from e
+            if self.assume_container_exists is None:
+                warnings.warn(
+                    f"Failed to fetch container properties for {container_name}. Assume it exists already",
+                )
+                return True
+            else:
+                raise ValueError(
+                    f"Failed to fetch container properties for {container_name} for {e}"
+                ) from e
         else:
             return True
 

adlfs/tests/test_spec.py

@@ -779,6 +779,7 @@ def test_mkdir(storage):
     fs = AzureBlobFileSystem(
         account_name=storage.account_name,
         connection_string=CONN_STR,
+        assume_container_exists=False,
     )
 
     # Verify mkdir will create a new container when create_parents is True
@@ -810,6 +811,22 @@ def test_mkdir(storage):
     with pytest.raises(PermissionError):
         fs.mkdir("new-container/dir", create_parents=False)
 
+    fs = AzureBlobFileSystem(
+        account_name=storage.account_name,
+        connection_string=CONN_STR,
+        assume_container_exists=None,
+    )
+
+    with pytest.warns():
+        fs.mkdir("bad_container_name")
+
+    fs = AzureBlobFileSystem(
+        account_name=storage.account_name,
+        connection_string=CONN_STR,
+        assume_container_exists=True,
+    )
+    fs.mkdir("bad_container_name")  # should not throw as we assume it exists
+
 
 def test_makedir(storage):
     fs = AzureBlobFileSystem(