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
Automatic OneAgent Ingestion	Yes

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.

Choose how to ingest data into Dynatrace

Auto-ingest for traces only

OneAgent currently only ingests traces automatically. If you are recording metrics or logs, choose the OTLP export route.

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

The initialization of OpenTelemetry varies, depending on whether you use OneAgent to send data to Dynatrace or perform an OTLP export.

Automatically instrument your application optional

Browse the OpenTelemetry registry and pick the instrumentation libraries matching your application libraries.

Install the applicable support libraries using go get.

go get go.opentelemetry.io/contrib/instrumentation/[PACKAGE_DETAILS]

Add the package to your import statements.

import (
  "go.opentelemetry.io/[PACKAGE]"
)

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

No example yet, as OpenTelemetry for Go does not have stable support for logs yet.

Depending on the status of the OpenTelemetry SDK, the pre-release version may nonetheless already allow the ingestion of your logs.

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 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).