$bytes_received

Description

In NGINX's stream module, the variable $bytes_received is dynamically set to reflect the number of bytes received from a client for the duration of a given connection. It helps in monitoring the amount of data a server has received through TCP or UDP data streams. Each time data is received from the client, this variable is updated accordingly and can be leveraged for logs or performance metrics. Consequently, $bytes_received essentially counts all bytes, including headers and payloads, making it a great tool for bandwidth analytics. This variable is initialized at the start of a connection and is available for use within various contexts related to active connections. For instance, within log formats, monitoring modules, or for implementing rate limiting based on the total bytes received. Typical values of $bytes_received can vary widely depending on the application but can usually scale from a few bytes to several megabytes or more during heavy loads, contingent on the type of traffic and configuration settings of the NGINX stream server.

Config Example

stream {
    server {
        listen 12345;
        access_log /var/log/nginx/stream_access.log "$remote_addr - $bytes_received bytes received";
    }
}