[Keyvault] az keyvault secret download: Add --overwrite flag (#31659)

Author: a0x1ab

src/azure-cli/azure/cli/command_modules/keyvault/_params.py

@@ -558,6 +558,7 @@ class CLISecurityDomainOperation(str, Enum):
         c.argument('encoding', arg_type=get_enum_type(secret_encoding_values), options_list=['--encoding', '-e'],
                    help="Encoding of the secret. By default, will look for the 'file-encoding' tag on the secret. "
                         "Otherwise will assume 'utf-8'.", default=None)
+        c.argument('overwrite', action='store_true', options_list=['--overwrite'], help="Overwrite the file if it exists.")
 
     for scope in ['download', 'backup', 'restore']:
         with self.argument_context('keyvault secret {}'.format(scope)) as c:

src/azure-cli/azure/cli/command_modules/keyvault/custom.py

@@ -1460,10 +1460,13 @@ def update_key_rotation_policy(cmd, client, value, key_name=None):
 
 
 # region KeyVault Secret
-def download_secret(client, file_path, name=None, encoding=None, version=''):  # pylint: disable=unused-argument
+def download_secret(client, file_path, name=None, encoding=None, version='', overwrite=False):  # pylint: disable=unused-argument
     """ Download a secret from a KeyVault. """
-    if os.path.isfile(file_path) or os.path.isdir(file_path):
-        raise CLIError("File or directory named '{}' already exists.".format(file_path))
+    if os.path.isdir(file_path):
+        raise CLIError("Cannot write to '{}': it is a directory.".format(file_path))
+
+    if not overwrite and os.path.isfile(file_path):
+        raise CLIError("File '{}' already exists. Use --overwrite to overwrite the existing file.".format(file_path))
 
     secret = client.get_secret(name, version)