Go

The WizeLens module#

Go has no agent: services use the OpenTelemetry SDK and the contrib instrumentation. The WizeLens module sets them up in a few lines and adds what they leave out.

go get github.com/brandonkorous/wizelens/go

import wizelens "github.com/brandonkorous/wizelens/go"

shutdown, err := wizelens.Start(ctx, wizelens.WithServiceName("inventory"))
defer shutdown(context.Background())

db, err := wizelens.OpenDB("pgx", dsn, "postgresql")              // queries, with their parameters
client := &http.Client{Transport: wizelens.Transport(nil)}       // outgoing calls carry the trace
log := wizelens.Logger("inventory", slog.Default().Handler())    // log.InfoContext(ctx, ...) joins the trace
http.ListenAndServe(":8080", wizelens.Handler(mux, "inventory")) // server spans, headers, bodies

Call	What it is
Start	Tracer and logger providers with OTLP over HTTP to WIZELENS_HUB, W3C trace context, and sampling that keeps every trace with an error or a slow span
OpenDB, DBOptions	otelsql with one span per query, named by its first word, plus wizelens.db.parameters
Handler, Capture	otelhttp plus request headers and, with WIZELENS_CAPTURE_BODY=true, request and response bodies
Transport	otelhttp's client transport
Logger	The otelslog bridge, also writing to your own handler

OTEL_EXPORTER_OTLP_ENDPOINT and the other OTEL_* variables still win when you set them.

Plain OpenTelemetry#

Already set up the SDK yourself? Point it at WizeLens and the insights work on its spans: N+1 queries, N+1 HTTP calls, slow queries, and database waits.

OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:5960
OTEL_EXPORTER_OTLP_HEADERS="Authorization=Bearer <token>"   # a shared hub or the cloud

Use the OTLP HTTP exporters (otlptracehttp, otlploghttp). Without parameters on query spans, WizeLens cannot tell whether two queries had the same values, so it does not call them duplicates. DBOptions() adds the parameters to your own otelsql.Open call.

Settings#

Variable	Default	What it does
WIZELENS_HUB	http://localhost:5960	Hub or cloud address
WIZELENS_HUB_TOKEN	none	Hub token or cloud ingest key
WIZELENS_PROJECT	none	Project on a shared hub
WIZELENS_SAMPLE_RATE	1	Share of traces kept. See Sampling
WIZELENS_KEEP_SLOW_MS	1000	Keep traces with a span this slow at any rate (off for none)
WIZELENS_KEEP_ERRORS	true	Keep traces with an error at any rate
WIZELENS_CAPTURE_BODY	false	Request and response bodies (text and JSON, 16 KB)
WIZELENS_CAPTURE_SQL_PARAMETERS	true	SQL parameters, sensitive names redacted
WIZELENS_CAPTURE_HEADERS	true	Request headers, secrets redacted
WIZELENS_REDACT_KEYS	none	More key fragments to redact, comma-separated
WIZELENS_ENABLED	true	false makes Start do nothing

A runnable sample#

samples/go-net-http is a net/http service with SQLite. GET /orders shows N+1 queries, a duplicate query, and N+1 HTTP calls; GET /report shows a slow query and a database wait; GET /fail shows an error with its log line.

cd samples/go-net-http
WIZELENS_CAPTURE_BODY=true go run .