重新部署Google Cloud Function丢失Python依赖问题

问题背景 #

我有一个包含main.py和requirements.txt的Google Cloud Function：

main.py

from superpackage.subpackage import TheSuperClass

def watch_function(event, context):
    print(f"Event ID: {context.event_id}")
    print(f"Event type: {context.event_type}")
    print("Bucket: {}".format(event["bucket"]))
    print("File: {}".format(event["name"]))
    print("Metageneration: {}".format(event["metageneration"]))
    print("Created: {}".format(event["timeCreated"]))
    print("Updated: {}".format(event["updated"]))
    a = TheSuperClass()

requirements.txt（通过Git仓库引用Python包，本地运行正常）：

-e git+https://github.com/someorg/superpackage.git@v0.2#egg=superpackage

首次部署使用以下命令成功，函数能正常响应存储桶文件上传事件：

gcloud functions deploy peter-function \
  --runtime python311 \
  --trigger-resource the-bucket-we-watch  \
  --entry-point watch_function \
  --trigger-event google.storage.object.finalize

问题现象：修改main.py后，用相同命令重部署同名函数时失败，提示找不到superpackage模块；但改用新函数名部署修改后的代码则正常运行。已将gcloud SDK更新至最新版本。

报错信息：

Deploying function (may take a while - up to 2 minutes)...failed.
ERROR: (gcloud.functions.deploy) OperationError: code=3, message=Function failed on loading user code. This is likely due to a bug in the user code. Error message: Traceback (most recent call last):
  File "/layers/google.python.pip/pip/bin/functions-framework", line 8, in <module>
    sys.exit(_cli())
             ^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/click/core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/click/core.py", line 1078, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/click/core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/click/core.py", line 783, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/functions_framework/_cli.py", line 37, in _cli
    app = create_app(target, source, signature_type)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.11/site-packages/functions_framework/__init__.py", line 288, in create_app
    spec.loader.exec_module(source_module)
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/workspace/main.py", line 1, in <module>
    from superpackage.subpackage import TheSuperClass
ModuleNotFoundError: No module named 'superpackage'. Please visit https://cloud.google.com/functions/docs/troubleshooting for in-depth troubleshooting documentation.

问题原因 #

这是Google Cloud Function增量部署的缓存机制导致的：重部署同名函数时，系统会复用已有运行环境的缓存，而requirements.txt中使用的-e（可编辑模式）Git包，在缓存复用过程中没有被正确重新加载，最终导致依赖缺失。而使用新函数名部署时会创建全新运行环境，能正常安装所有依赖。

解决方法 #

1. 部署时禁用缓存 #

在部署命令中添加--no-cache参数，强制系统重新构建运行环境并安装所有依赖：

gcloud functions deploy peter-function \
  --runtime python311 \
  --trigger-resource the-bucket-we-watch  \
  --entry-point watch_function \
  --trigger-event google.storage.object.finalize \
  --no-cache

2. 修改requirements.txt移除可编辑模式 #

将requirements.txt中的-e前缀移除，换成普通的Git包引用，避免缓存机制的兼容性问题：

git+https://github.com/someorg/superpackage.git@v0.2#egg=superpackage

修改后执行原部署命令即可。

3. 删除旧函数后重新部署 #

先删除已存在的函数，再重新部署，确保使用全新的运行环境：

gcloud functions delete peter-function
# 执行原部署命令
gcloud functions deploy peter-function \
  --runtime python311 \
  --trigger-resource the-bucket-we-watch  \
  --entry-point watch_function \
  --trigger-event google.storage.object.finalize

内容的提问来源于stack exchange，提问作者pjotr_dolphin