Instrument your Go application with OpenTelemetry

This walkthrough shows how to add observability to your Go application using the OpenTelemetry Go libraries and tools.

Feature

Supported

Automatic instrumentation

Yes

Traces

Yes

Metrics

Yes

Logs

Prerequisites

Dynatrace version 1.222+
For tracing, W3C Trace Context is enabled
1. Go to Settings > Preferences > OneAgent features.
2. Turn on Send W3C Trace Context HTTP headers.

Get the Dynatrace access details

Determine the API base URL

For details on how to assemble the base OTLP endpoint URL, see Export with OTLP. The URL should end in /api/v2/otlp.

Get API access token

The access token for ingesting traces, logs, and metrics can be generated under Access Tokens.

Export with OTLP has more details on the format and the necessary access scopes.

Choose how you want to instrument your application

OpenTelemetry supports on Go automatic and manual instrumentation, or a combination of both.

Which instrumentation should I choose?

It's a good idea to start with automatic instrumentation and add manual instrumentation if the automatic approach doesn't work or doesn't provide enough information.

Initialize OpenTelemetry

Add the following import statements.

import (
  "context"
  "github.com/Dynatrace/OneAgent-SDK-for-Go/sdk"
  "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/exporters/otlp/otlplog/otlploghttp"
  "go.opentelemetry.io/otel/propagation"
  "go.opentelemetry.io/otel/trace"
  sdkmetric "go.opentelemetry.io/otel/sdk/metric"
  "go.opentelemetry.io/otel/sdk/metric/metricdata"
  "go.opentelemetry.io/otel/sdk/resource"
  sdktrace "go.opentelemetry.io/otel/sdk/trace"
  semconv "go.opentelemetry.io/otel/semconv/v1.20.0"
  "log"
  "time"
  "log/slog"
  "go.opentelemetry.io/contrib/bridges/otelslog"
  "go.opentelemetry.io/otel/log/global"
  sdklog "go.opentelemetry.io/otel/sdk/log"
)

Run Go's mod tiny command to install the dependencies.
```
go mod tidy
```

Add the following code to your startup file and provide the respective values for DT_API_HOST and DT_API_TOKEN.

DT_API_HOST should contain only the hostname of your Dynatrace URL (for example, XXXXX.live.dynatrace.com); it is not a URL and must not contain any schemas or paths
DT_API_TOKEN should contain the access token

func InitOpenTelemetry() {

  // ===== GENERAL SETUP =====

  DT_API_HOST := "" // Only the host part of your Dynatrace URL
  DT_API_BASE_PATH := "/api/v2/otlp"
  DT_API_TOKEN := ""
  authHeader := map[string]string{"Authorization": "Api-Token " + DT_API_TOKEN}

  ctx := context.Background()

  oneagentsdk := sdk.CreateInstance()
  dtMetadata := oneagentsdk.GetEnrichmentMetadata()

  var attributes []attribute.KeyValue
  for k, v := range dtMetadata {
    attributes = append(attributes, attribute.KeyValue{Key: attribute.Key(k), Value: attribute.StringValue(v)})
  }
  attributes = append(attributes,
    semconv.ServiceNameKey.String("go-quickstart"), //TODO Replace with the name of your application
    semconv.ServiceVersionKey.String("1.0.1"),      //TODO Replace with the version of your application
  )

  res, err := resource.New(ctx, resource.WithAttributes(attributes...))
  if err != nil {
    log.Fatalf("Failed to create resource: %v", err)
  }

  
  // ===== TRACING SETUP =====

  exporter, err := otlptracehttp.New(
    ctx,
    otlptracehttp.WithEndpoint(DT_API_HOST),
    otlptracehttp.WithURLPath(DT_API_BASE_PATH+"/v1/traces"),
    otlptracehttp.WithHeaders(authHeader),
  )
  if err != nil {
    log.Fatalf("Failed to create OTLP exporter: %v", err)
  }

  tp := sdktrace.NewTracerProvider(
    sdktrace.WithResource(res),
    sdktrace.WithSampler(sdktrace.AlwaysSample()),
    sdktrace.WithBatcher(exporter),
  )
  otel.SetTracerProvider(tp)
  otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))


  // ===== METRIC SETUP =====

  var deltaTemporalitySelector = func(sdkmetric.InstrumentKind) metricdata.Temporality { return metricdata.DeltaTemporality }

  metricsExporter, err := otlpmetrichttp.New(
    ctx,
    otlpmetrichttp.WithEndpoint(DT_API_HOST),
    otlpmetrichttp.WithURLPath(DT_API_BASE_PATH+"/v1/metrics"),
    otlpmetrichttp.WithHeaders(authHeader),
    otlpmetrichttp.WithTemporalitySelector(deltaTemporalitySelector),
  )
  if err != nil {
    log.Fatalf("Failed to create OTLP exporter: %v", err)
  }

  mp := sdkmetric.NewMeterProvider(
    sdkmetric.WithResource(res),
    sdkmetric.WithReader(sdkmetric.NewPeriodicReader(metricsExporter, sdkmetric.WithInterval(2*time.Second))),
  )

  otel.SetMeterProvider(mp)


  // ===== LOG SETUP =====
  logExporter, err := otlploghttp.New(
    ctx,
    otlploghttp.WithEndpoint(DT_API_HOST),
    otlploghttp.WithURLPath(DT_API_BASE_PATH+"/v1/logs"),
    otlploghttp.WithHeaders(authHeader),
  )

  if err != nil {
    log.Fatalf("Failed to create OTLP exporter: %v", err)
  }

  lp := sdklog.NewLoggerProvider(
    sdklog.WithProcessor(sdklog.NewBatchProcessor(logExporter)),
    sdklog.WithResource(res),
  )

  global.SetLoggerProvider(lp)

  logger := otelslog.NewLogger("my-logger-scope", otelslog.WithLoggerProvider(lp))
  slog.SetDefault(logger) // here we are overwriting the sdtout to http logger exporter
}

Make sure to call InitOpenTelemetry as early as possible in your startup code to initialize OpenTelemetry.

Automatically instrument your application optional

Browse the OpenTelemetry registry and pick the instrumentation libraries matching your application libraries.
Add the relevant packages to your import statements.
```
import (
  "go.opentelemetry.io/[PACKAGE]"
)
```
Run Go's mod tiny command to install the dependencies.
```
go mod tidy
```
Wrap your existing code with calls to the support libraries.

Example for `net/http`

Install the instrumentation library for net/http.

Add the package to your import statements.

import (
  // other packages
  "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
)

Wrap your HTTP handler function.

handler := http.HandlerFunc(httpHandler)
wrappedHandler := otelhttp.NewHandler(handler, "my-span") //TODO Replace with the name of your span

//Use the wrappedHandler with your handle
http.Handle("/", wrappedHandler)

Manually instrument your application

Add tracing

You first need to get a tracer object.
```
tracer := otel.Tracer("my-tracer")
```
With tracer, you can now use a span builder to create and start new spans.
```
_, span := tracer.Start(r.Context(), "Call to /myendpoint")
defer span.End()

span.SetAttributes(attribute.String("http.method", "GET"), attribute.String("net.protocol.version", "1.1"))

// TODO your code goes here
```
In the code above, we:
- Create a new span and name it "Call to /myendpoint"
- Schedule a deferred call to End(), to ensure the span is properly closed when the function returns
- Add two attributes, following the semantic naming convention, specific to the action of this span: information on the HTTP method and version
- Add a TODO in place of the eventual business logic

Collect metrics

Obtain a meter object.
```
meter := otel.Meter("my-meter")
```
With meter, we can now create individual instruments, such as a counter.
```
requestCounter, _ := meter.Int64Counter("request_counter")
```
Now we can invoke the Add() method of requestCounter to record new values with the counter.
```
requestCounter.Add(context.Background(), 1)
```

Connect logs

With OpenTelemetry logging initialized in InitOpenTelemetry() and set as default logger for slog, we can now call any of slog's log functions (for example, Info()) to send our log information to Dynatrace.

slog.Info("an info message")
slog.Debug("a debug message")
slog.Error("an error")

Ensure context propagation optional

Context propagation is particularly important when network calls (for example, REST) are involved.

Extracting the context when receiving a request

In the following example, we assume that we have received a network call via the net/http library and its Request type.

To obtain a handle to the original context (which was provided by the calling service), we pass the HTTP header object (r.Header) to the Extract function of the global propagator singleton, which instantiates that context and returns in parentCtx. This allows us to continue the previous trace with our own spans.

func httpHandler(w http.ResponseWriter, r *http.Request) {
  parentCtx := otel.GetTextMapPropagator().Extract(r.Context(), propagation.HeaderCarrier(r.Header))

  tracer := otel.Tracer("my-tracer")
  ctx, span := tracer.Start(
    parentCtx,
    "manual-server", //TODO Replace with the name of your span
    trace.WithAttributes(
      attribute.String("my-key-1", "my-value-1"), //TODO Add attributes
    ),
  )
  defer span.End()

  //TODO your code goes here
}

Injecting the context when sending requests

In the following example, we set up a new instance of Request and pass the object to the Inject call of the global propagator singleton. This adds the necessary HTTP headers to the request object, which we eventually pass to Do to execute the network request.

client := http.Client{}

req, err := http.NewRequest("<method>", "<url>", <body>)
if err != nil {
  // TODO handle error
}

//Method to inject the current context in the request headers
otel.GetTextMapPropagator().Inject(ctx, propagation.HeaderCarrier(req.Header))

client.Do(req) // Your call goes here

Configure data capture to meet privacy requirements optional

While Dynatrace automatically captures all OpenTelemetry attributes, only attribute values specified in the allowlist are stored and displayed in the Dynatrace web UI. This prevents accidental storage of personal data, so you can meet your privacy requirements and control the amount of monitoring data stored.

To view your custom attributes, you need to allow them in the Dynatrace web UI first. To learn how to configure attribute storage and masking, see Attribute redaction.

Verify data ingestion into Dynatrace

Once you have finished the instrumentation of your application, perform a couple of test actions to create and send demo traces, metrics, and logs and verify that they were correctly ingested into Dynatrace.

To do that for traces, go to Distributed Traces or Distributed Traces Classic (latest Dynatrace) and select the Ingested traces tab. If you use OneAgent, select PurePaths instead.

For metrics and logs, go to Metrics or Logs or Logs & Events (latest Dynatrace).