Introduction

VarnishVision is intended to provide comprehensive observability for Varnish Cache environments. By leveraging OpenTelemetry, varnishlog (shared memory log), and varnishstat (statistics), VarnishVision will offer detailed insights into caching behavior, traffic flows, and system performance.

Environment Variables for the OpenTelemetry Exporter

These variables configure the different exporters for traces, metrics, and logs in Varnish.

Variable	Description	Possible Values	Default
OTEL_TRACES_EXPORTER	Defines the exporter used for traces	stdout, http, grpc, none	stdout
OTEL_METRICS_EXPORTER	Defines the exporter used for metrics	stdout, http, grpc, none	stdout
OTEL_LOGS_EXPORTER	Defines the exporter used for logs	stdout, http, grpc, none	stdout
OTEL_RESOURCE_ATTRIBUTES	Allows specifying resource attributes	String	-
OTEL_SERVICE_NAME	Name of the service used in instrumentation	String	varnish
OTEL_PROPAGATORS	Defines the propagators used for context propagation between services.	tracecontext, baggage, none	none
OTEL_TRACES_SAMPLER	Defines the sampler for traces	always_on, always_off	always_on
OTEL_TRACES_SAMPLER	Defines which logging tool to use for Varnish logs	ncsa, json	json
OTEL_VARNISH_NCSA_FORMAT_STRING	Specifies a custom format string for varnishncsa	String	-
OTEL_VARNISH_NCSA_FORMAT_FILE	Specifies a custom format file for varnishncsa	File path	-
OTEL_VARNISH_LOG_PROBE	Enables or disables log processing for backend probes	true, false	false
OTEL_VARNISH_LOG_TOOL	Defines which logging tool to use for Varnish logs	ncsa, json	json
OTEL_VARNISH_NCSA_FORMAT_STRING	Specifies a custom format string for varnishncsa	String	-
OTEL_VARNISH_NCSA_FORMAT_FILE	Specifies a custom format file for varnishncsa	File path	-
OTEL_VARNISH_LOG_PROBE	Enables or disables log processing for backend probes	true, false	false
OTEL_VARNISH_WORKDIR	`varnishd`’s `-n` argument	String	-
OTEL_VARNISH_METRICS_FILTER	Specifies filters to include or exclude certain metrics from export, via a comma separated list of globs passed to varnishncsa via -f	String	-
OTEL_METRIC_EXPORT_INTERVAL	The time interval (in milliseconds) between the start of two export attempts.	Integer	60000
OTEL_METRIC_EXPORT_TIMEOUT	Maximum allowed time (in milliseconds) to export data.	Integer	30000

Prerequisites

Install Varnish

Before anything else, make sure Varnish is already up and running. You can refer to our installation tutorials for detailed instructions.

You can also use the automated installation method for a quicker approach.

Install the Opentelemetry Exporter

Install the varnish-otlp-exporter package:

apt install -y ./varnish-otlp-exporter_0.0.1-1~focal_amd64.deb