Send Telemetry to Datadog from WebAssembly in Go

Overview

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

Installation

Install the Datadog adapter from GitHub:

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

Example

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

package main

import (
    "bytes"
    "context"
    "fmt"
    "io"
    "log"
    "net/http"
    "os"
    "path/filepath"

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

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

    // create a new Datadog Adapater with config
    // the default config assumes you have a datadog agent running on localhost
    ddconf := datadog.DefaultDatadogConfig()
    adapter := datadog.NewDatadogAdapter(ddconf)

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


    // 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)

    // setup some test metadata for Datadog to associate with the trace
    resourceName := "my-resource"
    httpUrl := "https://example.com/my-endpoint"
    httpStatusCode := 200
    spanKind := datadog.Server
    httpClientIp := "192.168.1.0"

    meta := datadog.DatadogMetadata{
        ResourceName:   &resourceName,
        HttpUrl:        &httpUrl,
        HttpStatusCode: &httpStatusCode,
        SpanKind:       &spanKind,
        HttpClientIp:   &httpClientIp,
    }
    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 := &DatadogConfig{
    // the URL of the Datadog agent
    AgentHost:   "http://localhost:8126",
    // the service name to group your observability data under
    ServiceName: "my-wasm-service",
    // default metadata that apply to every trace
    DefaultTags: nil,
    // the type of trace being captured
    TraceType:   datadog_formatter.Web,
    // how often to send traces to the agent
    FlushPeriod: 1 * time.Second,
    // the maximum number of traces to send to the agent per request
    BatchSize:   100,
}
adapter := NewDatadogAdapter(config)