ngnix - duplicate upstream "app_server" in /etc/nginx/sites-enabled/django - django

Question

Accidentally deleted conf nginx filled/etc/nginx/sites-enabled/django
, then filled it with the same configuration settings. got the following error:
Feb 02 12:56:53 solomon nginx[32004]: nginx: [emerg] duplicate upstream "app_server" in /etc/nginx/sites-enabled/django.save:1
Feb 02 12:56:53 solomon nginx[32004]: nginx: configuration file /etc/nginx/nginx.conf test failed
Feb 02 12:56:53 solomon systemd[1]: nginx.service: Control process exited, code=exited status=1
Feb 02 12:56:53 solomon sudo[31990]: pam_unix(sudo:session): session closed for user root
Feb 02 12:56:53 solomon systemd[1]: Failed to start A high performance web server and a reverse proxy server.
-- Subject: Unit nginx.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit nginx.service has failed.
--
-- The result is failed.
Feb 02 12:56:53 solomon systemd[1]: nginx.service: Unit entered failed state.
Feb 02 12:56:53 solomon systemd[1]: nginx.service: Failed with result 'exit-code'.
Configuration, which worked before for sure. Have I done something incorrectly ?:
upstream app_server {
server 127.0.0.1:9000 fail_timeout=0;
}
server {
listen 80 default_server;
listen [::]:80 default_server ipv6only=on;
root /usr/share/nginx/html;
index index.html index.htm;
client_max_body_size 4G;
server_name _;
keepalive_timeout 5;
# Your Django project's media files - amend as required
location /media {
alias /home/django/django_project/django_project/media;
}
# your Django project's static files - amend as required
location /static {
alias /home/django/django_project/django_project/static;
}
location / {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_redirect off;
proxy_pass http://app_server;
}
}

Answer 1

If you have other configuration files in the directory(/etc/nginx/sites-enabled/django) with same upstream name as 'app_server ' then you get that duplicate upstream error.
So replace 'app_server' to any other name. run nginx -t to check for any errors, then restart nginx,

Answer 2

If you tape in your terminal cat /etc/nginx/nginx.conf
you will see these two lines:
include /etc/nginx/conf.d/*.conf;
Wich means Nginx load all files .conf (for example if you are using dokku to deploy your app, you will see dokku.conf which contain "include /home/dokku/*/nginx.conf;" itself) and this means loading all /home/dokku/whatever-folder/nginx.conf
include /etc/nginx/sites-enabled/*;

Answer 3

This problem came up in my case because my configuration file was in /etc/nginx/conf.d and I also had a symbolic link to it in /etc/nginx/sites-enabled/. Not sure how nginx loads the files but apparently it was loaded twice. No matter what name I chose for the upstream, I got duplicate error. Deleting symbolic link fixed the problem.

Answer 4

If the same upstream name "app_server" is not found, find the same upstream name with different case,like:
upstream app_server {
server 127.0.0.1:9000
}
upstream App_server {
server 127.0.0.1:9000
}
This may also cause conflicts. It may be the setting of nginx, but I haven't found the document yet