Set Up Logs in Go

Structured logs allow you to send, view, and query logs sent from your applications within Sentry.

With Sentry Structured Logs, you can send text-based log information from your applications to Sentry. Once in Sentry, these logs can be viewed alongside relevant errors, searched by text-string, or searched using their individual attributes.

Logs in Go are supported in Sentry Go SDK version 0.33.0 and above. To use integrations with other logging libraries, check their specific documentation pages for detailed requirements.

To enable logging, you need to initialize the SDK with the EnableLogs option set to true.

Copied
package main

import (
	"fmt"
	"time"

	"github.com/getsentry/sentry-go"
)

func main() {
	if err := sentry.Init(sentry.ClientOptions{
		Dsn:        "https://examplePublicKey@o0.ingest.sentry.io/0",
		// Enable logs to be sent to Sentry
		EnableLogs: true,
	}); err != nil {
		fmt.Printf("Sentry initialization failed: %v\n", err)
	}
	// Flush buffered events before the program terminates.
	defer sentry.Flush(2 * time.Second)
}

Once the feature is enabled on the SDK and the SDK is initialized, you can send logs by using the sentry.Logger API or our different integrations.

The sentry.Logger API exposes methods that support six different log levels:

  • trace
  • debug
  • info
  • warn
  • error
  • fatal

The methods support both fmt.Print and fmt.Printf like syntax. If you pass in format specifiers like %v, these will be sent to Sentry, and can be searched from within the Logs UI, and even added to the Logs views as a dedicated column.

Copied
func main() {
	if err := sentry.Init(sentry.ClientOptions{
		Dsn:        "https://examplePublicKey@o0.ingest.sentry.io/0",
		EnableLogs: true,
	}); err != nil {
		log.Fatalf("Sentry initialization failed: %v", err)
	}
	// Flush buffered events before the program terminates.
	// Set the timeout to the maximum duration the program can afford to wait.
	defer sentry.Flush(2 * time.Second)

    // The SentryLogger requires context, to link logs with the appropriate traces. You can either create a new logger
	// by providing the context, or use WithCtx() to pass the context inline.
	ctx := context.Background()
	logger := sentry.NewLogger(ctx)

	// Or inline using WithCtx()
    newCtx := context.Background()
    // WithCtx() does not modify the original context attached on the logger.
	logger.Info().WithCtx(newCtx).Emit("context passed")

	// You can use the logger like [fmt.Print]
	logger.Info().Emit("Hello ", "world!")
	// Or like [fmt.Printf]
	logger.Info().Emitf("Hello %v!", "world")
}

You can also pass additional permanent attributes to the logger via SetAttributes, or attach certain attributes to the LogEntry itself. These attributes do not persist after Emitting the LogEntry. All attributes will be searchable in the Logs UI.

Copied
logger.SetAttributes(
    attribute.Int("key.int", 42),
    attribute.Bool("key.boolean", true),
    attribute.Float64("key.float", 42.4),
    attribute.String("key.string", "string"),
)
logger.Warn().Emitf("I have params: %v and attributes", "example param")

// This entry would contain all attributes attached to the logger.
// However, it's also possible to overwrite them.
logger.Info().String("key.string", "newstring").Emit("overwriting key.string")

Currently, the attribute API supports only these value types: int, string, bool, and float.

The sentry.Logger implements the io.Writer interface, so you can easily inject the logger into your existing setup. However, to correctly link your traces you would need to create a new logger everytime you want to pass a new context. Due to this limitation we recommend using the sentry.Logger or any of the other supported integrations.

Copied
sentryLogger := sentry.NewLogger(ctx)
logger := log.New(sentryLogger, "", log.LstdFlags)
logger.Println("Implementing log.Logger")

To filter logs, or update them before they are sent to Sentry, you can use the BeforeSendLog client option.

Copied
sentry.Init(sentry.ClientOptions{
    Dsn:        "https://examplePublicKey@o0.ingest.sentry.io/0",
    EnableLogs: true,
    BeforeSendLog: func(log *sentry.Log) *sentry.Log {
        // filter out all trace logs
        if log.Level == sentry.LogLevelTrace {
            return nil
        }

        // filter all logs below warning
        if log.Severity <= sentry.LogSeverityInfo {
            return nil
        }
        return log
    },
})

If the Debug init option is set to true, calls to the sentry.Logger will also print to the console with the appropriate log level.

In order to properly attach the correct trace with each log entry, a context.Context is required. If you're using logs combined with tracing, you should pass the correct context to properly attach each trace with the appropriate logs.

The Go SDK automatically sets several default attributes on all log entries to provide context and improve debugging:

  • environment: The environment set in the SDK if defined. This is sent from the SDK as sentry.environment.
  • release: The release set in the SDK if defined. This is sent from the SDK as sentry.release.
  • trace.parent_span_id: The span ID of the span that was active when the log was collected (only set if there was an active span). This is sent from the SDK as sentry.trace.parent_span_id.
  • sdk.name: The name of the SDK that sent the log. This is sent from the SDK as sentry.sdk.name. This is sent from the SDK as sentry.sdk.name.
  • sdk.version: The version of the SDK that sent the log. This is sent from the SDK as sentry.sdk.version. This is sent from the SDK as sentry.sdk.version.

If the log was paramaterized, Sentry adds the message template and parameters as log attributes.

  • message.template: The parameterized template string. This is sent from the SDK as sentry.message.template.
  • message.parameter.X: The parameters to fill the template string. X can either be the number that represent the parameter's position in the template string (sentry.message.parameter.0, sentry.message.parameter.1, etc) or the parameter's name (sentry.message.parameter.item_id, sentry.message.parameter.user_id, etc). This is sent from the SDK as sentry.message.parameter.X.

For example, with the following log:

Copied
ctx := context.Background()
logger := sentry.NewLogger(ctx)

logger.Info().Emitf("A %s log message", "formatted")

Sentry will add the following attributes:

  • message.template: "A %s log message"
  • message.parameter.0: "formatted"

  • server.address: The address of the server that sent the log. Equivalent to server_name that gets attached to Sentry errors.

If user information is available in the current scope, the following attributes are added to the log:

  • user.id: The user ID.
  • user.name: The username.
  • user.email: The email address.

If a log is generated by an SDK integration, the SDK will set additional attributes to help you identify the source of the log.

  • origin: The origin of the log. This is sent from the SDK as sentry.origin.
Previous
Set Up Tracing
Next
Set Up Crons
Was this helpful?
Help improve this content
Our documentation is open source and available on GitHub. Your contributions are welcome, whether fixing a typo (drat!) or suggesting an update ("yeah, this would be better").