Send Telemetry to Lightstep from WebAssembly in Go

Overview

Enables the extraction of traces/spans from Wasm modules executing in a Golang program/application and emits them to Lightstep.

Installation

Install the Lightstep adapter from GitHub:

go get github.com/dylibso/observe-sdk/go/adapter/lightstep@latest

Example

A basic Go program that loads a Wasm module and executes it using the Wazero WebAssembly runtime.

package main

import (
    "context"
    "log"
    "os"
    "time"

    "github.com/dylibso/observe-sdk/go/adapter/lightstep"
    "github.com/tetratelabs/wazero"
    "github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
)

func main() {
    // create a context
    ctx := context.Background()

    // create a new Lightstep adapter with config
    conf := &lightstep.LightstepConfig{
        ApiKey:             os.Getenv("LIGHTSTEP_API_KEY"),
        ServiceName:        "golang",
        EmitTracesInterval: time.Second * 1,
        TraceBatchMax:      100,
        Host:               "https://ingest.lightstep.com",
    }

    adapter := lightstep.NewLightstepAdapter(conf)

    // start the Observe SDK adapter
    defer adapter.Stop(true)
    adapter.Start(ctx)

    // load some Wasm from disk
    wasm, err := os.ReadFile(os.Args[1])
    if err != nil {
        log.Panicln(err)
    }

    // setup a new Wazero runtime with config
    wacfg := wazero.NewRuntimeConfig().WithCustomSections(true)
    rt := wazero.NewRuntimeWithConfig(ctx, wacfg)

    // apply the Observe SDK adapter to the Wazero runtime
    traceCtx, err := adapter.NewTraceCtx(ctx, rt, wasm, nil)
    if err != nil {
        log.Panicln(err)
    }

    wasi_snapshot_preview1.MustInstantiate(ctx, rt)

    // create a new Wazero configuration
    modconfig := wazero.NewModuleConfig().
        WithStdin(os.Stdin).
        WithStdout(os.Stdout).
        WithStderr(os.Stderr).
        WithArgs(os.Args[1:]...).
        WithStartFunctions("_start")

    // instantiate the Wasm module
    mod, err := rt.InstantiateWithConfig(ctx, wasm, modconfig)
    if err != nil {
        log.Println("module instance error:", err)
        return
    }
    defer mod.Close(ctx)

    // associate some additional metadata with the trace
    meta := map[string]string{
        "http.url":         "https://example.com/my-endpoint",
        "http.status_code": "200",
        "http.client_ip":   "192.168.1.0",
    }
    traceCtx.Metadata(meta)

    // stop the trace 
    traceCtx.Finish()
}

Adapter Configuration

You may modify the behavior of your adapter by passing in a configuration when initializing the adapter. A configuration has the following fields:

config := &LightstepConfig{
    // the URL of your OpenTelemetry collector
    Host:               "https://ingest.lightstep.com",
    // your Lightstep API key
    ApiKey:             os.Getenv("LIGHTSTEP_API_KEY"),
    // the dataset to group your observability data under
    Dataset:            "golang",
    // how often to send traces
    EmitTracesInterval: time.Second * 1,
    // the maximum number of traces to send per request
    TraceBatchMax:      100,
}
adapter := NewLightstepAdapter(config)