OpenTelemetry Go SDK¶

Go アプリケーション + OpenTelemetry Go SDK -> OTLP -> DataKit -> Guance

cd /usr/local/datakit/conf.d/opentelemetry
sudo cp opentelemetry.conf.sample opentelemetry.conf

[[inputs.opentelemetry]]
  # カスタム属性を Guance でタグとして保持するには、ここにホワイトリストを追加します。
  # 属性名のドットはアンダースコアに変換されます（例：team.name -> team_name）。
  customer_tags = ["team", "project"]

  [inputs.opentelemetry.http]
    http_status_ok = 200
    trace_api = "/otel/v1/traces"
    metric_api = "/otel/v1/metrics"
    logs_api = "/otel/v1/logs"

  [inputs.opentelemetry.grpc]
    addr = "127.0.0.1:4317"
    max_payload = 16777216

sudo datakit service restart

curl http://127.0.0.1:9529/v1/ping

go get go.opentelemetry.io/otel
go get go.opentelemetry.io/otel/sdk
go get go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp
go get go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp
go get go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp
go mod tidy

package main

import (
    "context"
    "errors"
    "fmt"
    "log"
    "net/http"
    "os"
    "os/signal"
    "syscall"
    "time"

    "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
    "go.opentelemetry.io/otel"
    "go.opentelemetry.io/otel/attribute"
    "go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
    "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
    "go.opentelemetry.io/otel/propagation"
    sdkmetric "go.opentelemetry.io/otel/sdk/metric"
    "go.opentelemetry.io/otel/sdk/resource"
    sdktrace "go.opentelemetry.io/otel/sdk/trace"
)

func setupOTelSDK(ctx context.Context) (func(context.Context) error, error) {
    res, err := resource.New(
        ctx,
        resource.WithFromEnv(),
        resource.WithTelemetrySDK(),
        resource.WithHost(),
        resource.WithOS(),
        resource.WithProcess(),
    )
    if err != nil {
        return nil, fmt.Errorf("create resource: %w", err)
    }

    traceExporter, err := otlptracehttp.New(ctx)
    if err != nil {
        return nil, fmt.Errorf("create trace exporter: %w", err)
    }

    tracerProvider := sdktrace.NewTracerProvider(
        sdktrace.WithResource(res),
        sdktrace.WithSampler(
            sdktrace.ParentBased(sdktrace.TraceIDRatioBased(1.0)),
        ),
        sdktrace.WithBatcher(traceExporter),
    )

    metricExporter, err := otlpmetrichttp.New(ctx)
    if err != nil {
        _ = tracerProvider.Shutdown(ctx)
        return nil, fmt.Errorf("create metric exporter: %w", err)
    }

    meterProvider := sdkmetric.NewMeterProvider(
        sdkmetric.WithResource(res),
        sdkmetric.WithReader(
            sdkmetric.NewPeriodicReader(
                metricExporter,
                sdkmetric.WithInterval(30*time.Second),
            ),
        ),
    )

    otel.SetTracerProvider(tracerProvider)
    otel.SetMeterProvider(meterProvider)
    otel.SetTextMapPropagator(
        propagation.NewCompositeTextMapPropagator(
            propagation.TraceContext{},
            propagation.Baggage{},
        ),
    )

    shutdown := func(ctx context.Context) error {
        return errors.Join(
            meterProvider.Shutdown(ctx),
            tracerProvider.Shutdown(ctx),
        )
    }
    return shutdown, nil
}

func main() {
    ctx, stop := signal.NotifyContext(
        context.Background(),
        os.Interrupt,
        syscall.SIGTERM,
    )
    defer stop()

    shutdown, err := setupOTelSDK(ctx)
    if err != nil {
        log.Fatal(err)
    }
    defer func() {
        shutdownCtx, cancel := context.WithTimeout(
            context.Background(),
            5*time.Second,
        )
        defer cancel()
        if err := shutdown(shutdownCtx); err != nil {
            log.Printf("shutdown OpenTelemetry: %v", err)
        }
    }()

    meter := otel.Meter("example/order-service")
    requestCounter, err := meter.Int64Counter("app.request.count")
    if err != nil {
        log.Fatal(err)
    }

    mux := http.NewServeMux()
    mux.Handle("/hello", otelhttp.NewHandler(
        http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            requestCtx, span := otel.Tracer("example/order-service").Start(
                r.Context(),
                "prepare-response",
            )
            defer span.End()

            span.SetAttributes(attribute.String("app.route", "/hello"))
            requestCounter.Add(requestCtx, 1)
            _, _ = fmt.Fprintln(w, "hello from OpenTelemetry Go SDK")
        }),
        "GET /hello",
    ))

    server := &http.Server{
        Addr:              ":8080",
        Handler:           mux,
        ReadHeaderTimeout: 5 * time.Second,
    }

    go func() {
        <-ctx.Done()
        shutdownCtx, cancel := context.WithTimeout(
            context.Background(),
            5*time.Second,
        )
        defer cancel()
        if err := server.Shutdown(shutdownCtx); err != nil {
            log.Printf("shutdown HTTP server: %v", err)
        }
    }()

    log.Println("listening on http://127.0.0.1:8080")
    if err := server.ListenAndServe(); !errors.Is(err, http.ErrServerClosed) {
        log.Fatal(err)
    }
}

export OTEL_SERVICE_NAME="order-service"
export OTEL_RESOURCE_ATTRIBUTES="deployment.environment.name=prod,service.version=1.0.0,team=backend"

export OTEL_EXPORTER_OTLP_ENDPOINT="http://127.0.0.1:9529/otel"
export OTEL_EXPORTER_OTLP_INSECURE="true"
export OTEL_EXPORTER_OTLP_COMPRESSION="gzip"

go run .

curl http://127.0.0.1:8080/hello

go get go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc
go get go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc
go mod tidy

traceExporter, err := otlptracegrpc.New(ctx)
metricExporter, err := otlpmetricgrpc.New(ctx)

export OTEL_EXPORTER_OTLP_ENDPOINT="http://127.0.0.1:4317"
export OTEL_EXPORTER_OTLP_INSECURE="true"