update serving command

setup.py

@@ -38,9 +38,9 @@ from setuptools import find_packages, setup
 
 
 extras = {
-    'serving': ['uvicorn', 'fastapi'],
-    'serving-tf': ['uvicorn', 'fastapi', 'tensorflow'],
-    'serving-torch': ['uvicorn', 'fastapi', 'torch']
+    'serving': ['pydantic', 'uvicorn', 'fastapi'],
+    'serving-tf': ['pydantic', 'uvicorn', 'fastapi', 'tensorflow'],
+    'serving-torch': ['pydantic', 'uvicorn', 'fastapi', 'torch']
 }
 extras['all'] = [package for package in extras.values()]
 

transformers-cli

@@ -3,9 +3,9 @@ from argparse import ArgumentParser
 
 from transformers.commands.download import DownloadCommand
 from transformers.commands.run import RunCommand
-from transformers.commands.serving import ServeCommand
 from transformers.commands.user import UserCommands
 from transformers.commands.convert import ConvertCommand
+from transformers.commands.serving import ServeCommand
 
 if __name__ == '__main__':
     parser = ArgumentParser('Transformers CLI tool', usage='transformers-cli <command> [<args>]')

transformers/commands/serving.py

@@ -1,16 +1,23 @@
 from argparse import ArgumentParser, Namespace
 from typing import List, Optional, Union, Any
 
-from fastapi import FastAPI, HTTPException, Body
-from logging import getLogger
+import logging
 
-from pydantic import BaseModel
+try:
     from uvicorn import run
+    from fastapi import FastAPI, HTTPException, Body
+    from pydantic import BaseModel
+    _serve_dependancies_installed = True
+except (ImportError, AttributeError):
+    BaseModel = object
+    Body = lambda *x, **y: None
+    _serve_dependancies_installed = False
 
 from transformers import Pipeline
 from transformers.commands import BaseTransformersCLICommand
 from transformers.pipelines import SUPPORTED_TASKS, pipeline
 
+logger = logging.getLogger('transformers-cli/serving')
 
 def serve_command_factory(args: Namespace):
     """
@@ -70,13 +77,17 @@ class ServeCommand(BaseTransformersCLICommand):
         serve_parser.set_defaults(func=serve_command_factory)
 
     def __init__(self, pipeline: Pipeline, host: str, port: int):
-        self._logger = getLogger('transformers-cli/serving')
 
         self._pipeline = pipeline
 
-        self._logger.info('Serving model over {}:{}'.format(host, port))
         self._host = host
         self._port = port
+        if not _serve_dependancies_installed:
+            raise ImportError("Using serve command requires FastAPI and unicorn. "
+                                "Please install transformers with [serving]: pip install transformers[serving]." 
+                                "Or install FastAPI and unicorn separatly.")
+        else:
+            logger.info('Serving model over {}:{}'.format(host, port))
             self._app = FastAPI()
 
             # Register routes