Connections management

This section cosiders capabilities of the nginx to manage connections.

This section requires http_stub_status_module to be installed in nginx, so a custom build of nginx is used here.

docker run -itd --name experiment_nginx --rm -p 80:80 custom_nginx

a481aba9f5ef3bbcd4a7dab744bfc3bdcf5cc0402dff5e5d99a8038b0951ced3

Note: Don’t forget to clean up the environment.

docker stop experiment_nginx

experiment_nginx

Connections monitoring

You can check information about active connections using tools provided by http_stub_status_module. Check corresponding page of the official documentation.

---

The following cell creates an endpoint that uses the `stub_status’ directive to create a special endpoint that provides information about the number of busy workers.

docker exec -i experiment_nginx sh -c 'cat >  /etc/nginx/nginx.conf' << EOF
events {}
http {
    server {
        location = /basic_status {
            stub_status;
        }
    }
}
EOF

docker exec experiment_nginx nginx -s reload

Here is the result of invoking the built endpoint.

curl localhost:80/basic_status

Active connections: 1 
server accepts handled requests
 1 1 1 
Reading: 0 Writing: 1 Waiting: 0 

Worker connections

Nginx provides a configuration option to specify how many simultaneous connections it can support. This is controlled by the worker_connections directive within the events block. It defines the maximum number of connections Nginx can handle at the same time.

For more details, refer to the official documentation.

---

The following cell sets up nginx to have only two worker connections - that’s the minimum number for nginx to run.

docker exec -i experiment_nginx sh -c 'cat >  /etc/nginx/nginx.conf' <<EOF
events {worker_connections 2;}
http {server{return 200 "hello";}}
EOF
docker exec -i experiment_nginx nginx -s reload

Any message will simply return nothing.

curl localhost:80

curl: (52) Empty reply from server

The same configuration with worker_connections set to 3 works fine.

docker exec -i experiment_nginx sh -c 'cat >  /etc/nginx/nginx.conf' <<EOF
events {worker_connections 3;}
http {server{return 200 "hello";}}
EOF
docker exec -i experiment_nginx nginx -s reload

curl localhost:80

hello