Go OpenTelemetry Instrumentation

This document contains instructions on how to set up OpenTelemetry instrumentation in your Go applications and view your application traces in SigNoz.

Send Traces to SigNoz Cloud

From VMs, there are two ways to send data to SigNoz Cloud.

Send traces directly to SigNoz Cloud

  1. Install Dependencies
    Dependencies related to OpenTelemetry exporter and SDK have to be installed first. Note that we are assuming you are using gin request router. If you are using other request routers, check out the corresponding package.

    Run the below commands after navigating to the application source folder:

    go get go.opentelemetry.io/otel \
  go.opentelemetry.io/otel/trace \
  go.opentelemetry.io/otel/sdk \
  go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin \
  go.opentelemetry.io/otel/exporters/otlp/otlptrace \
  go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc

  2. Declare environment variables for configuring OpenTelemetry
    Declare the following global variables in main.go which we will use to configure OpenTelemetry:

     var (
     serviceName  = os.Getenv("SERVICE_NAME")
     collectorURL = os.Getenv("OTEL_EXPORTER_OTLP_ENDPOINT")
     insecure     = os.Getenv("INSECURE_MODE")
 )

  3. Instrument your Go application with OpenTelemetry
    To configure your application to send data we will need a function to initialize OpenTelemetry. Add the following snippet of code in your main.go file.

        
import (
    .....

    "google.golang.org/grpc/credentials"
    "github.com/gin-gonic/gin"
    "go.opentelemetry.io/otel"
    "go.opentelemetry.io/otel/attribute"
    "go.opentelemetry.io/otel/exporters/otlp/otlptrace"
    "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"

    "go.opentelemetry.io/otel/sdk/resource"
    sdktrace "go.opentelemetry.io/otel/sdk/trace"
)

func initTracer() func(context.Context) error {

    var secureOption otlptracegrpc.Option

    if strings.ToLower(insecure) == "false" || insecure == "0" || strings.ToLower(insecure) == "f" {
        secureOption = otlptracegrpc.WithTLSCredentials(credentials.NewClientTLSFromCert(nil, ""))
    } else {
        secureOption = otlptracegrpc.WithInsecure()
    }

    exporter, err := otlptrace.New(
        context.Background(),
        otlptracegrpc.NewClient(
            secureOption,
            otlptracegrpc.WithEndpoint(collectorURL),
        ),
    )

    if err != nil {
        log.Fatalf("Failed to create exporter: %v", err)
    }
    resources, err := resource.New(
        context.Background(),
        resource.WithAttributes(
            attribute.String("service.name", serviceName),
            attribute.String("library.language", "go"),
        ),
    )
    if err != nil {
        log.Fatalf("Could not set resources: %v", err)
    }

    otel.SetTracerProvider(
        sdktrace.NewTracerProvider(
            sdktrace.WithSampler(sdktrace.AlwaysSample()),
            sdktrace.WithBatcher(exporter),
            sdktrace.WithResource(resources),
        ),
    )
    return exporter.Shutdown
}

  4. Initialize the tracer in main.go
    Modify the main function to initialise the tracer in main.go. Initiate the tracer at the very beginning of our main function.

    func main() {
    cleanup := initTracer()
    defer cleanup(context.Background())

    ......
}

  5. Add the OpenTelemetry Gin middleware
    Configure Gin to use the middleware by adding the following lines in main.go.

    import (
    ....
  "go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin"
)

func main() {
    ......
    r := gin.Default()
    r.Use(otelgin.Middleware(serviceName))
    ......
}

  6. Set environment variables and run your Go Gin application
    The run command must have some environment variables to send data to SigNoz cloud. The run command:

    SERVICE_NAME=<service_name> INSECURE_MODE=false OTEL_EXPORTER_OTLP_HEADERS=signoz-ingestion-key=<your-ingestion-key>
OTEL_EXPORTER_OTLP_ENDPOINT=ingest.<region>.signoz.cloud:443 go run main.go
    • Set the <region> to match your SigNoz Cloud region
    • Replace <your-ingestion-key> with your SigNoz ingestion key.
    • <service_name> is name of your service

Send traces via OTel Collector binary

  1. Install OTel Collector binary

OTel Collector binary helps to collect logs, hostmetrics, resource and infra attributes.

You can find instructions to install OTel Collector binary here in your VM.

  1. Install Dependencies
    Dependencies related to OpenTelemetry exporter and SDK have to be installed first. Note that we are assuming you are using gin request router. If you are using other request routers, check out the corresponding package.

    Run the below commands after navigating to the application source folder:

    go get go.opentelemetry.io/otel \
  go.opentelemetry.io/otel/trace \
  go.opentelemetry.io/otel/sdk \
  go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin \
  go.opentelemetry.io/otel/exporters/otlp/otlptrace \
  go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc

  2. Declare environment variables for configuring OpenTelemetry
    Declare the following global variables in main.go which we will use to configure OpenTelemetry:

     var (
     serviceName  = os.Getenv("SERVICE_NAME")
     collectorURL = os.Getenv("OTEL_EXPORTER_OTLP_ENDPOINT")
     insecure     = os.Getenv("INSECURE_MODE")
 )

  3. Instrument your Go application with OpenTelemetry
    To configure your application to send data we will need a function to initialize OpenTelemetry. Add the following snippet of code in your main.go file.

         
 import (
     .....

     "google.golang.org/grpc/credentials"
     "github.com/gin-gonic/gin"
     "go.opentelemetry.io/otel"
     "go.opentelemetry.io/otel/attribute"
     "go.opentelemetry.io/otel/exporters/otlp/otlptrace"
     "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"

     "go.opentelemetry.io/otel/sdk/resource"
     sdktrace "go.opentelemetry.io/otel/sdk/trace"
 )

 func initTracer() func(context.Context) error {

     var secureOption otlptracegrpc.Option

     if strings.ToLower(insecure) == "false" || insecure == "0" || strings.ToLower(insecure) == "f" {
         secureOption = otlptracegrpc.WithTLSCredentials(credentials.NewClientTLSFromCert(nil, ""))
     } else {
         secureOption = otlptracegrpc.WithInsecure()
     }

     exporter, err := otlptrace.New(
         context.Background(),
         otlptracegrpc.NewClient(
             secureOption,
             otlptracegrpc.WithEndpoint(collectorURL),
         ),
     )

     if err != nil {
         log.Fatalf("Failed to create exporter: %v", err)
     }
     resources, err := resource.New(
         context.Background(),
         resource.WithAttributes(
             attribute.String("service.name", serviceName),
             attribute.String("library.language", "go"),
         ),
     )
     if err != nil {
         log.Fatalf("Could not set resources: %v", err)
     }

     otel.SetTracerProvider(
         sdktrace.NewTracerProvider(
             sdktrace.WithSampler(sdktrace.AlwaysSample()),
             sdktrace.WithBatcher(exporter),
             sdktrace.WithResource(resources),
         ),
     )
     return exporter.Shutdown
 }

  4. Initialize the tracer in main.go
    Modify the main function to initialise the tracer in main.go. Initiate the tracer at the very beginning of our main function.

    func main() {
    cleanup := initTracer()
    defer cleanup(context.Background())

    ......
}

  5. Add the OpenTelemetry Gin middleware
    Configure Gin to use the middleware by adding the following lines in main.go.

    import (
    ....
  "go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin"
)

func main() {
    ......
    r := gin.Default()
    r.Use(otelgin.Middleware(serviceName))
    ......
}

  6. Set environment variables and run your Go Gin application
    The run command must have some environment variables to send data to SigNoz. The run command:

    SERVICE_NAME=<service_name> INSECURE_MODE=true OTEL_EXPORTER_OTLP_ENDPOINT=localhost:4317 go run main.go

    <service_name> is name of your service

  7. You can validate if your application is sending traces to SigNoz cloud by following the instructions here.

Validating instrumentation by checking for traces

With your application running, you can verify that you’ve instrumented your application with OpenTelemetry correctly by confirming that tracing data is being reported to SigNoz.

To do this, you need to ensure that your application generates some data. Applications will not produce traces unless they are being interacted with, and OpenTelemetry will often buffer data before sending. So you need to interact with your application and wait for some time to see your tracing data in SigNoz.

Validate your traces in SigNoz:

  1. Trigger an action in your app that generates a web request. Hit the endpoint a number of times to generate some data. Then, wait for some time.
  2. In SigNoz, open the Services tab. Hit the Refresh button on the top right corner, and your application should appear in the list of Applications.
  3. Go to the Traces tab, and apply relevant filters to see your application’s traces.

You might see other dummy applications if you’re using SigNoz for the first time. You can remove it by following the docs here.

If you don't see your application reported in the list of services, try our troubleshooting guide.

Request Routers

OpenTelemetry gin/gonic instrumentation

# Add one line to your import() stanza depending upon your request router:
middleware "go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin"

and then inject OpenTelemetry middleware:

router.Use(middleware.Middleware(serviceName))

OpenTelemetry gorillamux instrumentation

# Add one line to your import() stanza depending upon your request router:
middleware "go.opentelemetry.io/contrib/instrumentation/github.com/gorilla/mux/otelmux"

and then inject OpenTelemetry middleware:

router.Use(middleware.Middleware(serviceName))

OpenTelemetry echo instrumentation

# Add one line to your import() stanza depending upon your request router:
middleware "go.opentelemetry.io/contrib/instrumentation/github.com/labstack/echo/otelecho"

and then inject OpenTelemetry middleware:

router.Use(middleware.Middleware(serviceName))

If you don’t use a request router

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

In each place where you pass an http.Handler to a ServeMux, you’ll wrap the handler function. For instance, you’ll make the following replacements:

- mux.Handle("/path", h)
+ mux.Handle("/path", otelhttp.NewHandler(h, "description of path"))

- mux.Handle("/path", http.HandlerFunc(f))
+ mux.Handle("/path", otelhttp.NewHandler(http.HandlerFunc(f), "description of path"))

In this fashion, you can ensure that every function you wrap with othttp will automatically have its metadata collected and a corresponding trace started.

Adding custom attributes and custom events to spans

It’s also possible to set custom attributes or tags to a span. To add custom attributes and events follow the below steps:

  1. Import trace and attribute libraries

    import (
    ...
    "go.opentelemetry.io/otel/attribute"
    "go.opentelemetry.io/otel/trace"
)

  2. Fetch current span from context

    span := trace.SpanFromContext(c.Request.Context())

  3. Set attribute on current

    span.SetAttributes(attribute.String("controller", "books"))

We can also set custom events on the span with its own attribute.

span.AddEvent("This is a sample event", trace.WithAttributes(attribute.Int("pid", 4328), attribute.String("sampleAttribute", "Test")))

gRPC Instrumentation with OpenTelemetry

OpenTelemetry can also help you automatically instrument gRPC requests. To instrument any gRPC servers you have.

import (
    "go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
)

func main() {
  [...]

    // add StatsHandler to gRPC server initialization
	s := grpc.NewServer(grpc.StatsHandler(otelgrpc.NewServerHandler()))

}

Similarly, instrument your gRPC client as well by adding otelgrpc when initializing gRPC client

import (
    "go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
)

func main() {
  [...]

    // add StatsHandler to gRPC client initialization
	cc, err := grpc.NewClient(serverUrl, grpc.WithTransportCredentials(insecure.NewCredentials()),
		grpc.WithStatsHandler(otelgrpc.NewClientHandler()),
	)

}

We have a blog Monitor gRPC calls with OpenTelemetry - explained with a Golang example, do refer to that in case you need a helping hand to work with gRPC server.

Recording Errors and Exceptions

import "go.opentelemetry.io/otel/codes"

// Get the current span from the tracer
span := trace.SpanFromContext(ctx)

// RecordError converts an error into a span event.
span.RecordError(err)

// Mark span as failed.
span.SetStatus(codes.Error, "internal error")

Sample Golang application

We have included a sample gin/gonic application with README.md at https://github.com/SigNoz/sample-golang-app.

Feel free to use this repo to test out OpenTelemetry instrumentation and how to send telemetry data to SigNoz.

Library and framework support

Besides OpenTelemetry core modules, it is important to install instrumentation packages for every important library and framework which your service depends upon. Beyond the critical telemetry data these components emit, library and framework integrations are often required to ensure that the trace context is properly propagated.

OpenTelemetry automatically provides instrumentation for a large number of libraries and frameworks, right out of the box.

The full list of supported instrumentation can be found in the README.

You can also find libraries, plugins, integrations, and other useful tools for extending OpenTelemetry from the OpenTelemetry registry.

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