Firstly I have read probably every stackoverflow post related to this topic this Easter weekend. E.g. upstream prematurely closed connection (uwsgi + nginx + django) does not solve my problem because it was poor code which didnt even run via manage.py runserver. Most of the posts are about timeouts. This error is thrown immediately on a file that is less than 30KB. All my timeouts on Nginx and uWSGI are set at the default of 60s. It is not a timeout issue, but maybe a cache issue.
I write some info from the database into a .xlsx file using openpyxl. When I return the file, it is about 27KB and it has about a 50% chance of not throwing the error. If it is quite a bit larger it fails every time, if it is quite a bit smaller it's okay every time. All other webpages work fine for the site. This is the error message:
2019/04/21 20:14:52 [error] 19712#19712: *46 upstream prematurely closed connection while reading response header from upstream, client: ipaddress, server: request: "GET / HTTP/1.1", upstream: "uwsgi://unix:////var/run/uwsgi.sock:", host: "www.mysite.com"
The file can be downloaded successfully via manage.py runserver. It also runs successfully when I start uWSGI directly. The only time it does not work is when Nginx passes the request to uWSQI, and then Nginx immediately fails when retrieving the response. Hence I have been going through Nginx documentation trying to find something.
This is my Nginx setup, set up a cache region:
uwsgi_cache_path /var/www/my_site/public/nginx_uwsgi_temp levels=1:2 keys_zone=myzone:64m inactive=10m;
And the virtual host part, with a mess of unsuccessful attempts from: http://nginx.org/en/docs/http/ngx_http_uwsgi_module.html
# Finally, send all non-media requests to the Django server.
location / {
uwsgi_pass django;
# the uwsgi_params file you installed
include /home/somefolders/uwsgi_params;
# http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_read_timeout
# Timeouts when talking to uWSGI
# proxy_read_timeout 60s; # Default 60s
# proxy_send_timeout 60s; # Default 60s
# proxy_connect_timeout 60s; # Default 60s
# Trying uwsgi protocol, within uwsgi .ini set "protocol = uwsgi"
# http://nginx.org/en/docs/http/ngx_http_uwsgi_module.html
uwsgi_read_timeout 60s; # Default value 60s
uwsgi_send_timeout 60s; # Default value 60s
# uwsgi_cache
# uwsgi_buffering on;
# uwsgi_buffer_size 8k;
# uwsgi_max_temp_file_size 1024m;
# uwsgi_temp_path /var/www/public/nginx_uwsgi_temp 1 2;
# client cache
uwsgi_cache myzone;
# uwsgi_cache_revalidate on;
# uwsgi_cache_key $uri;
# uwsgi_cache_valid any 10m;want
# add_header X-Cache-Status $upstream_cache_status ;
uwsgi_buffer_size 320k;
uwsgi_buffers 8 320k;
uwsgi_busy_buffers_size 320k;
uwsgi_next_upstream off;
}
I could be barking up the wrong tree, but all my attempts point towards some Nginx configuration of cache.
I find it interesting that by default Nginx is set with:
uwsgi_buffers 8 4k
Which is about 8*4=24kb, about the point at which things start breaking down.
