examples

Sentry Integration Examples for mtlog

Send your Go application logs to Sentry with structured context, breadcrumbs, and error tracking.

Quick Start

Prerequisites

• Docker and Docker Compose installed
• Go 1.21 or later
• About 5GB of disk space for Sentry containers

Step 1: Set Up Local Sentry

From the mtlog root directory:

# 1. Download and configure Sentry (one-time setup)
./adapters/sentry/scripts/setup-integration-test.sh

# 2. Navigate to docker directory
cd docker

# 3. Start and initialize Sentry
../adapters/sentry/scripts/initialize-sentry-pipeline.sh

# 4. Verify everything is working
../adapters/sentry/scripts/verify-sentry-pipeline.sh

The initialization script will display your DSN. Save it for the next step:

DSN: http://[your-key]@localhost:9000/1

Step 2: Run the Examples

Set your DSN and run any example:

# Set the DSN from Step 1
export SENTRY_DSN="http://[your-key]@localhost:9000/1"

# Run an example
cd adapters/sentry/examples/basic
go run main.go

Step 3: View Events in Sentry

1. Open http://localhost:9000 in your browser
2. Log in with:
   • Email: admin@test.local
   • Password: admin
3. Navigate to Issues to see your logged errors

Examples Overview

📁 basic/

Simple error logging with Sentry integration

Shows the fundamentals of sending errors to Sentry:

• Creating a Sentry sink with DSN
• Logging errors that appear as issues in Sentry
• Basic configuration options

// Create Sentry sink
sentrySink, _ := sentry.WithSentry(dsn,
    sentry.WithEnvironment("production"),
    sentry.WithRelease("v1.0.0"),
)

// Log an error - this will appear in Sentry
logger.Error("Payment failed: {Error}", paymentErr)

Run it: cd basic && go run main.go

📁 breadcrumbs/

Shows how debug/info logs become breadcrumbs attached to errors

Demonstrates Sentry's breadcrumb trail feature:

• Info and Debug logs are captured as breadcrumbs
• When an error occurs, breadcrumbs provide context
• Shows the user's journey leading to the error

// These become breadcrumbs
logger.Debug("User session started")
logger.Information("Loading user preferences")
logger.Warning("Slow query detected")

// This error will have all the above as breadcrumbs
logger.Error("Transaction failed: {Error}", err)

Run it: cd breadcrumbs && go run main.go

📁 context/

Demonstrates adding user context and custom tags

Advanced context enrichment:

• Attach user information to errors
• Add custom tags for filtering in Sentry
• Set request context for API errors
• Custom device and location data

// Add user context
ctx = sentry.WithUser(ctx, sentrygo.User{
    ID:    "user-123",
    Email: "user@example.com",
})

// Add custom tags
ctx = sentry.WithTags(ctx, map[string]string{
    "region": "us-west-2",
    "plan":   "premium",
})

// Errors will include this context
logger.WithContext(ctx).Error("Subscription failed")

Run it: cd context && go run main.go

Configuration Guide

Basic Configuration

sentrySink, err := sentry.WithSentry(dsn)

With Options

sentrySink, err := sentry.WithSentry(dsn,
    // Environment (development, staging, production)
    sentry.WithEnvironment("production"),
    
    // Release version for tracking deployments
    sentry.WithRelease("v1.2.3"),
    
    // Server/host identification
    sentry.WithServerName("api-server-01"),
    
    // Only send Error and Fatal levels to Sentry
    sentry.WithMinLevel(core.ErrorLevel),
    
    // Capture Debug and above as breadcrumbs
    sentry.WithBreadcrumbLevel(core.DebugLevel),
    
    // Maximum breadcrumbs to attach (default: 100)
    sentry.WithMaxBreadcrumbs(100),
)

Using with mtlog

logger := mtlog.New(
    mtlog.WithConsole(),           // Local console output
    mtlog.WithSink(sentrySink),    // Send to Sentry
)
defer logger.Close()

// Use the logger normally
logger.Information("User {UserId} logged in", userId)
logger.Error("Payment failed: {Error}", err)

How It Works

When you log an error with mtlog's Sentry integration:

1. Error Level: Messages at Error or Fatal level are sent to Sentry as events
2. Breadcrumbs: Lower level logs (Debug, Info, Warning) become breadcrumbs
3. Context: User info, tags, and custom data are automatically attached
4. Grouping: Errors are grouped by message template in Sentry
5. Rich Data: Stack traces, environment info, and metadata are preserved

The message template becomes the issue title in Sentry, making it easy to track error patterns:

• "Database timeout for {Table}" → Groups all database timeouts together
• "Payment failed: {Error}" → Groups payment failures by error type

Testing with Production Sentry

To use with Sentry SaaS instead of local:

1. Get your DSN from your Sentry project settings
2. Set the environment variable:

   export SENTRY_DSN="https://[key]@sentry.io/[project]"

3. Run any example normally

Troubleshooting

Events Not Appearing in Sentry UI

1. Check the DSN: Ensure SENTRY_DSN is set correctly
2. Wait a moment: Events can take a few seconds to appear
3. Check filters: The Sentry UI may be filtering by date/environment
4. Verify services: Run ../scripts/verify-sentry-pipeline.sh

Common Issues

• "Please set SENTRY_DSN": Export the DSN environment variable
• Connection refused: Sentry services aren't running. Run the initialization script
• No events after restart: Services need reinitialization after Docker restart

Stopping Sentry

To stop the local Sentry instance:

cd docker
docker-compose -f docker-compose.test.yml down

To completely remove all data:

docker-compose -f docker-compose.test.yml down -v

Further Reading

• mtlog Documentation
• Sentry Go SDK Documentation
• Sentry Event Context