使用 nginx + WSGI 运行 Flask 应用程序时 Python 子进程出错

Question

I have developed a Python web server using Flask, and some of the endpoints make use of the subprocess module to call different executables. On development, using the Flask debug server, everything works fine. However, when running the server along with nginx+WSGI (on the exact same machine), some subprocess calls fail.

For example, one of the tools I'm using is Microsoft's do.net, which I installed from my user as sudo apt-get install -y as.netcore-runtime-5.0 and is then called from Python with the subprocess module. When I run the server with python3 server.py , it works like a charm. However, when using nginx and WSGI, the subprocess call fails with an exception that says: /bin/sh: 1: do.net: not found .

I suspect this is due to the command not being accessible to the user and group running the server. I have used this guide as a reference to deploy the app, and on the wsgi.ini file, I have set uid = javierd and gid = www-data , while on the systemd.service file I have User=javierd , Group=www-data .

I have tried to add the executables' paths to /etc/profile , but it didn't work, and I don't know any other way to fix it. I find also very surprising that this happens to some executables, but not to all, and that it happes to do.net, for example, which is located at /usr/bin/do.net and therefore should be accessible to every user. Any idea on how to solve this problem? Furthermore, if somebody could explain me why this is happening, I would really appreciate the effort.

Thanks a lot!

Answer 1

Ok, finally after having a big headache, I noticed the error, and it was really simple.

On the tutorial I linked, when creating the system service file, the following line was included: Environment="PATH=/home/myuser/myfolder/enviroment/bin" .

Of course, as this was overriding the path, there was no way of executing the commands. Once I notices it I just removed that line, restarted the service, and it was fixed.