How do you disable caching for an nginx+uwsgi+python server?

Question

I am trying to do development of a completely fresh website using exclusively nginx, uwsgi, and python. The problem is that if I change the file that uwsgi points to, and refresh the page, I get the HTML generated by the previous version of the file. It seems that nginx, uwsgi, or both are caching the code and/or response of my site. I have been reading up on uwsgi caching but have not been able to disable caching using the --cache2 flag and --cache_* flags. I found this other question and also attempted to use

proxy_no_cache "1";
proxy_cache_bypass "1";

in the server's location dictionary (located at /etc/nginx/sites-available/mysite), but alas it still caches the page. I have used web2py in the past with nginx and uwsgi and it doesn't seem to have this issue when I updated controllers or views.

This is my site file:

server { 
    listen 80 default_server; 
    listen [::]:80 default_server; 
    listen 443 ssl default_server; 
    listen [::]:443 ssl default_server; 
    include snippets/snakeoil.conf; 
    server_name _; 
    location / {
        include uwsgi_params; 
        uwsgi_pass 127.0.0.1:3031;
    }
}

this is the executed program that the init.d script uses:

uwsgi --master --processes 4 --threads 2 --die-on-term -s /tmp/mysock.sock --socket :3031 --uid www-data --gid www-data --vacuum --wsgi-file /path/to/my/python/file.py

this is the python file that is loaded:

def application(environ, start_response): 
    start_response('200 OK', [('Content-Type', 'text/html')])
    return ["<h1>Hello World</h1>"]

I understand that caching improves performance, so I intend to turn it back on for a production environment, but developing with it turned on is a pain in the butt... What am I doing wrong?

My only workaround right now is to restart the uwsgi service everytime I make a change :(

Answer 1

SOLVED

Alright, I figured it out thanks to Guan Hao. His comment on web frameworks having an "auto-reload" feature set me on the path of determining how web2py works so seamlessly when modifying controllers, models, and views. As it turns out, I do have to reload uwsgi before my changes take effect and in the end I found a method (although not the best) that allows me to do development without requiring a shell to issue an /etc/init.d/mysiteapp restart everytime I make changes. According to the uWSGI documentation, there exists a --touch-reload flag that you can specify when starting uWSGI that will reload it when a certain file is modified/touched.

touch-reload
argument: required_argument
parser: uwsgi_opt_add_string_list
flags: UWSGI_OPT_MASTER
help: reload uWSGI if the specified file is modified/touched

I simply set the argument for the flag to a file called reload sitting in the root directory of the website and when I upload changes, I simply upload that file as well (at the very end). It works flawlessly! Thank you for the tip! I have two days before I can accept my own answer, so if anyone has a better method than this one, please feel free to post it.

--- UPDATE ---

It turns out there is an even better way of doing this! I stumbled across this question that has a unaccepted answer which solved the issue completely (so far). With this method I don't even have to touch the reload file. I simply added the following flag and parameter to uwsgi when it is executed in the init.d script:

--py-autoreload 1

I am not sure why I could never find the answer in Google searches and whatnot, but I could care less now that I have the perfect solution! Please beware, anyone who uses this, that you should remove the flag in production.

Answer 2

It's not caching. You have to restart uwsgi before your changes made to python files take effect.

You may also enable the auto-reload feature of your web framework(web2py or whatever). In that case, the wsgi app will reload itself when it detects file changes, so you don't need to restart uwsgi.