部署Django站点到Heroku时psycopg2初始化报错原因排查

错误日志 #

2023-05-05T08:42:38.330672+00:00 app[web.1]: from psycopg2._psycopg import ( # noqa
2023-05-05T08:42:38.330672+00:00 app[web.1]: SystemError: initialization of _psycopg raised unreported exception
2023-05-05T08:42:38.330718+00:00 app[web.1]: [2023-05-05 08:42:38 +0000] [8] [INFO] Worker exiting (pid: 8)
2023-05-05T08:42:38.367087+00:00 app[web.1]: [2023-05-05 08:42:38 +0000] [2] [WARNING] Worker with pid 8 was terminated due to signal 15
2023-05-05T08:42:38.465035+00:00 app[web.1]: [2023-05-05 08:42:38 +0000] [2] [INFO] Shutting down: Master
2023-05-05T08:42:38.465071+00:00 app[web.1]: [2023-05-05 08:42:38 +0000] [2] [INFO] Reason: Worker failed to boot.
2023-05-05T08:42:38.616316+00:00 heroku[web.1]: Process exited with status 3
2023-05-05T08:42:38.666808+00:00 heroku[web.1]: State changed from starting to crashed
2023-05-05T08:42:39.000000+00:00 app[api]: Build succeeded
2023-05-05T08:42:44.863150+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=a-coders-journey.herokuapp.com request_id=d8e2f6b2-c4f5-461f-8914-a8e84dc13551 fwd="93.204.33.78" dyno= connect= service= status=503 bytes= protocol=https

当前配置与已尝试操作 #

requirements.txt内容 #

#
# This file is autogenerated by pip-compile with Python 3.8
# by the following command:
#
#    pip-compile --output-file=requirements.txt requirements.in
#
asgiref==3.3.4
    # via
    #   -r requirements.in
    #   django
certifi==2022.12.7
    # via
    #   cloudinary
    #   requests
cffi==1.15.1
    # via cryptography
charset-normalizer==3.1.0
    # via requests
cloudinary==1.25.0
    # via
    #   -r requirements.in
    #   dj3-cloudinary-storage
cryptography==3.4.8
    # via
    #   -r requirements.in
    #   pyjwt
defusedxml==0.7.1
    # via python3-openid
dj-database-url==0.5.0
    # via -r requirements.in
dj3-cloudinary-storage==0.0.5
    # via -r requirements.in
django==3.2.3
    # via
    #   -r requirements.in
    #   django-allauth
    #   django-summernote
django-allauth==0.44.0
    # via -r requirements.in
django-crispy-forms==1.11.2
    # via -r requirements.in
django-summernote==0.8.11.6
    # via -r requirements.in
gunicorn==20.1.0
    # via -r requirements.in
idna==3.4
    # via requests
oauthlib==3.1.1
    # via
    #   -r requirements.in
    #   requests-oauthlib
pillow==9.5.0
    # via -r requirements.in
psycopg2-binary
    # via -r requirements.in
pycparser==2.21
    # via cffi
pyjwt[crypto]==2.1.0
    # via
    #   -r requirements.in
    #   django-allauth
python3-openid==3.2.0
    # via
    #   -r requirements.in
    #   django-allauth
pytz==2021.1
    # via
    #   -r requirements.in
    #   django
requests==2.30.0
    # via
    #   dj3-cloudinary-storage
    #   django-allauth
    #   requests-oauthlib
requests-oauthlib==1.3.0
    # via
    #   -r requirements.in
    #   django-allauth
six==1.16.0
    # via cloudinary
sqlparse==0.4.1
    # via
    #   -r requirements.in
    #   django
urllib3==2.0.2
    # via
    #   cloudinary
    #   requests

# The following packages are considered to be unsafe in a requirements file:
# setuptools

settings.py相关配置 #

from pathlib import Path
import os
import psycopg2
import dj_database_url
if os.path.isfile('env.py'):
    import env

# ...其他代码...

DATABASE_URL = os.environ['DATABASE_URL']

conn = psycopg2.connect(DATABASE_URL, sslmode='require')

# 文件末尾
DATABASES['default'] = dj_database_url.config(conn_max_age=600, ssl_require=True)

已尝试操作 #

• 确认requirements.txt包含psycopg2-binary
• 按Heroku文档配置数据库
• 添加runtime.txt尝试统一Python版本（本地3.8.12，Heroku原用3.11.3）
• 验证env.py和Heroku配置变量指向elephantSQL数据库
• 联系Heroku支持但问题未解决

疑问 #

哪里操作有误？为何psycopg2初始化时会报错？

解决方案 #

• 移除settings.py中手动建立psycopg2连接的代码
  Django通过dj_database_url.config()配置后会自动管理数据库连接，无需手动调用psycopg2.connect()。提前执行该代码会导致Django启动时过早加载psycopg2底层库，此时环境未完全初始化，引发未上报的初始化异常。删除以下两行：

  DATABASE_URL = os.environ['DATABASE_URL']
  conn = psycopg2.connect(DATABASE_URL, sslmode='require')
  

• 锁定psycopg2-binary的兼容版本
  当前requirements.txt中psycopg2-binary未指定版本，pip会拉取最新版本，但最新版本可能与Python 3.8不兼容。将其修改为psycopg2-binary==2.9.6（该版本经验证可稳定运行在Python 3.8和Heroku环境），之后重新运行pip-compile生成新的requirements.txt。

• 强制Heroku使用与本地一致的Python版本
  确保runtime.txt内容为python-3.8.12，避免Heroku默认使用高版本Python（如3.11）导致依赖编译不兼容。

• 清理Heroku缓存并重新部署
  旧缓存可能残留不兼容的依赖编译文件，执行以下命令清理后重新推送代码：

  heroku apps:clear-cache -a a-coders-journey
  git add .
  git commit -m "Fix psycopg2 initialization error"
  git push heroku main
  

内容的提问来源于stack exchange，提问作者ENJ