$connection_time

Description

The $connection_time variable in NGINX captures the duration, in seconds, it takes to establish a connection to a client after NGINX has received the request. This value is determined at the time the connection is established, enabling the measurement of latency from the perspective of the NGINX server. The variable is updated as part of the connection processing flow and is primarily suitable for logging or metrics collection associated with connection times. Common values might range from fractions of a second in optimal conditions to multiple seconds in scenarios with high latencies or connection issues. The context of when $connection_time is set starts as soon as the NGINX worker process accepts a new connection from a client, which corresponds to the moment the request begins to be processed. Developers and administrators can use this variable to gain insights into performance characteristics, especially when monitoring the behavior of the web server under various network conditions or loads. Analyzing these values can help in deducing the health of the server and identifying potential performance bottlenecks related to client connections.

Config Example

log_format main '$remote_addr - $remote_user [$time_local] "$request" ' \
                    '$status $body_bytes_sent "$http_referer" ' \
                    '"$http_user_agent" "$http_x_forwarded_for" ' \
                    'Connection time: $connection_time';

access_log /var/log/nginx/access.log main;