log_append

Appends a field to the access log for the current request.

This should be used alongside the log directive which is required to enable access logging in the first place.

The value may be a static string, or a placeholder which will be replaced with the value of the placeholder at the time of the request.

Syntax

log_append [<matcher>] <key> <value>

Examples

Display in the logs the area of the site that the request is being served from, either static or dynamic:

example.com {
	log

	handle /static* {
		log_append area "static"
		respond "Static response!"
	}

	handle {
		log_append area "dynamic"
		reverse_proxy localhost:9000
	}
}

Display in the logs, which reverse proxy upstream was effectively used (either node1, node2 or node3) and the time spent proxying to the upstream in milliseconds as well as how long it took the proxy upstream to write the response header:

example.com {
	log

	handle {
		reverse_proxy node1:80 node2:80 node3:80 {
			lb_policy random_choose 2 
		}
		log_append upstream_host {rp.upstream.host}
		log_append upstream_duration_ms {rp.upstream.duration_ms}
		log_append upstream_latency_ms {rp.upstream.latency_ms}
	}
}