部署Flask API至GCP App Engine时遇main模块找不到错误

错误信息 #

2023-05-16 07:49:30 default[20230516t084639]  Traceback (most recent call last):    
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/gunicorn/arbiter.py", line 589, in spawn_worker      
worker.init_process()    
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/gunicorn/workers/gthread.py", line 92, in init_process      
super().init_process()    
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/gunicorn/workers/base.py", line 134, in init_process      
self.load_wsgi()    
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/gunicorn/workers/base.py", line 146, in load_wsgiapp      
self.wsgi = self.app.wsgi()    
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/gunicorn/app/base.py", line 67, in wsgi      
self.callable = self.load()    
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/gunicorn/app/wsgiapp.py", line 58, in load      
return self.load_wsgiapp()    
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/gunicorn/app/wsgiapp.py", line 48, in load_wsgiapp      
return util.import_app(self.app_uri) 
File "/layers/google.python.pip/pip/lib/python3.9/site-packages/gunicorn/util.py", line 359, in import_app      
mod = importlib.import_module(module)    
File "/layers/google.python.runtime/python/lib/python3.9/importlib/__init__.py", line 127, in import_module      
return _bootstrap._gcd_import(name[level:], package, level)    
File "<frozen importlib._bootstrap>", line 1030, in _gcd_import    
File "<frozen importlib._bootstrap>", line 1007, in _find_and_load    
File "<frozen importlib._bootstrap>", line 984, in _find_and_load_unlocked  
ModuleNotFoundError: No module named 'main'

相关配置与代码 #

app.yaml #

runtime: python39
entrypoint: gunicorn -b :$PORT main:app

instance_class: F1

automatic_scaling:
  target_cpu_utilization: 0.65
  min_instances: 1
  max_instances: 10

main.py #

from flask import Blueprint, jsonify, request, send_file, current_app, Flask
from app.services.commitgraph import (
    fetch_commit_count_per_day,
    plot_commit_count,
    RepoNotFoundError,
    NoCommitsFoundError,
    InvalidUsername,
    THEMES,
    TYPES,
)

app = Flask(__name__)

@app.route("/v1/commit-graph", methods=["GET"])
def get_commit_graph():
    # 代码省略
    pass

if __name__ == "__main__":
    app.run(debug=True)

requirements.txt #

blinker==1.6.2
certifi==2023.5.7
charset-normalizer==3.1.0
click==8.1.3
colorama==0.4.6
contourpy==1.0.7
cycler==0.11.0
Flask==2.3.2
fonttools==4.39.4
gunicorn==20.1.0
idna==3.4
importlib-metadata==6.6.0
importlib-resources==5.12.0
itsdangerous==2.1.2
Jinja2==3.1.2
kiwisolver==1.4.4
MarkupSafe==2.1.2
matplotlib==3.7.1
numpy==1.24.3
packaging==23.1
pandas==2.0.1
Pillow==9.5.0
pyparsing==3.0.9
python-dateutil==2.8.2
pytz==2023.3
requests==2.30.0
scipy==1.10.1
six==1.16.0
tzdata==2023.3
urllib3==2.0.2
Werkzeug==2.3.4
zipp==3.15.0

项目结构 #

project_root/
    main.py
    app.yaml
    requirements.txt
    app/
        __init__.py
        api/
            __init__.py
    services/
        commitgraph.py

解决方案 #

1. 修正导入路径
   main.py中错误地将services目录放在app子目录下导入，实际services与main.py同级，需修改导入语句：

   # 原语句
   # from app.services.commitgraph import (...)
   # 修改为
   from services.commitgraph import (
       fetch_commit_count_per_day,
       plot_commit_count,
       RepoNotFoundError,
       NoCommitsFoundError,
       InvalidUsername,
       THEMES,
       TYPES,
   )
   

2. 添加services目录的__init__.py
   在services目录下创建空的__init__.py文件，让Python将其识别为可导入模块：

   project_root/
       services/
           __init__.py
           commitgraph.py
   

3. 确认部署命令执行目录
   必须在项目根目录下运行gcloud app deploy，确保GCP能找到main.py和app.yaml文件。

4. 验证entrypoint配置
   当前app.yaml中的entrypointgunicorn -b :$PORT main:app是正确的，只要main.py在根目录且定义了app对象，无需修改。

内容的提问来源于stack exchange，提问作者Kyzoki