varnishlog_exporter

Summary

varnishlog_exporter is an exporter for prometheus that counts occurrences in the varnish shared memory log of specific tags and headers and reports the accumulated counts.

Exported metrics

Cstom log metrics

At any point in the VCL code, it can be decorated with a log message of the format logkey:something. This will generate a metric of type varnish_custom_counter with the label key set to something. This gives maximum flexibility, and in VCL it's possible to write something like:

import std;

sub vcl_recv {
   ...
   if (...) {
      std.log('logkey:awesome');
   }
}

to track specific occurrences.

Request and response header metrics

If specific headers are added to the commandline using -reqheader or -respheader (for request headers and response headers respectively), these headers will be automatically tracked. If no header is specified on the commandline, none will be tracked (as tracking all headers would likely lead to extreme metrics bloat). These headers will be exported as metrics of type varnish_header_counter. Each metric will get a label type set to either req or resp, a label header with the name of the header, and a label value with the unique value.

For example, something like:

$ varnishlog_exporter -respheader Server -respheader Content-Type

will export for example:

varnish_header_counter{header="Server",type="resp",value="nginx/1.4.6 (Ubuntu)"}
varnish_header_counter{header="Content-Type",type="resp",value="text/html"}
varnish_header_counter{header="Content-Type",type="resp",value="text/plain"}

(with each having the count of the number of requests matching it).

Tracking status codes

If -statuscodes is included on the commandline, per-statuscode statistics are collected. These are both collected as a label on varnish_header_counter, and as a global metrics with the total number of requests and size.

Tracking http versions

If -httpversions is included on the commandline, metrics are collected for http versions. This is done by looking at the ReqProtocol value in Varnish, and will collect on number of requests and total size of those requests.

Tracking probe response times

If -probes is included on the commandline, metrics are collected for probe response times. Each probe will be recorded as a Summary, meaning it will get a count and a sum.

Usage

-httpversions
	Include statistics per http version
-probes
	Inlcude probe statistics
-reqheader value
  	Request header to include
-respheader value
  	Response header to include
-statuscodes
	Include statistics per statuscode
-varnish.name string
  	Name of varnish instance to connect to.
-version
  	Print version information.
-web.listen-address string
  	Address to listen on for web interface and telemetry. (default ":9132")
-web.telemetry-path string
  	Path under which to expose metrics. (default "/metrics")