logger

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Check out other SmooAI packages at smoo.ai/open-source

About smooai-logger (Go)

The missing piece for AWS & Go logging - A contextual logging system that automatically captures the full execution context you need to debug production issues, without the manual setup.

Go Package

A Go port of @smooai/logger that mirrors the feature set of the TypeScript, Python, and Rust versions. The package exposes a JSON-first logging API with correlation tracking, HTTP helpers, AWS Lambda integration, optional pretty-printing, and rotating-file output — all idiomatic Go with no global init required.

Why smooai-logger?

Ever spent hours debugging a Go service in production, only to realize you're missing critical context? Traditional loggers give you the message, but not the story.

smooai-logger automatically captures:

For AWS Services:

• Exact code location - File, line number, and function name for every log
• Request journey - Correlation IDs that follow requests across services
• AWS context - Service-specific metadata and execution details
• HTTP details - Headers, methods, status codes from API Gateway
• Message context - SQS attributes, EventBridge events, SNS messages
• Service integration - Lambda, ECS, Fargate, EC2, and more

Install

go get github.com/SmooAI/logger/go/v4

Cross-Language Support

The same structured log format works across all your services:

The Power of Automatic Context

See Where Your Logs Come From

Every log entry includes the exact location in your code:

import logger "github.com/SmooAI/logger/go/v4"

log := logger.Default()
log.Info("User created")

// Output includes:
{
  "caller": {
    "file":     "src/services/user_service.go",
    "line":     42,
    "function": "UserService.CreateUser"
  }
}

No more guessing which function logged what - the full call site is right there.

Track Requests Across Services

Correlation IDs automatically flow through your entire system:

// Service A: API Gateway Handler
lambdaLog.AddAPIGatewayContext(request)
lambdaLog.Info("Request received")  // Correlation ID: abc-123

// Service B: SQS Processor (automatically extracts ID from message)
lambdaLog.AddSQSRecordContext(record)
lambdaLog.Info("Processing message")  // Same Correlation ID: abc-123

// Service C: Another Lambda (receives via HTTP header)
lambdaLog.Info("Completing workflow")  // Still Correlation ID: abc-123

Production-Ready Examples

AWS Lambda with API Gateway

package main

import (
    "context"

    "github.com/aws/aws-lambda-go/events"
    "github.com/aws/aws-lambda-go/lambda"
    logger "github.com/SmooAI/logger/go/v4"
)

var log *logger.LambdaLogger

func init() {
    base, _ := logger.New(logger.Options{Name: "UserAPI"})
    log = logger.NewLambdaLogger(base)
}

func handler(ctx context.Context, request events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
    log.AddLambdaContext(ctx)
    log.AddAPIGatewayContext(request)

    user, err := createUser(request.Body)
    if err != nil {
        log.Error("Failed to create user", err, map[string]any{
            "body":    request.Body,
            "headers": request.Headers,
        })
        return events.APIGatewayProxyResponse{StatusCode: 500}, err
    }

    log.Info("User created successfully", map[string]any{"userId": user.ID})
    return events.APIGatewayProxyResponse{StatusCode: 201}, nil
}

func main() {
    lambda.Start(handler)
}

AWS ECS/Fargate Services

import (
    "os"
    logger "github.com/SmooAI/logger/go/v4"
)

log, _ := logger.New(logger.Options{
    Name:  "OrderService",
    Level: logger.LevelInfo,
})

// Add container metadata for ECS/Fargate
log.AddContext(logger.Map{
    "taskArn":       os.Getenv("ECS_TASK_ARN"),
    "containerName": os.Getenv("ECS_CONTAINER_NAME"),
})

log.Info("Processing order", map[string]any{
    "orderId": orderId,
    "amount":  amount,
})

SQS Message Processing

func sqsHandler(ctx context.Context, event events.SQSEvent) error {
    for _, record := range event.Records {
        lambdaLog.AddSQSRecordContext(record)
        lambdaLog.Info("Processing message", map[string]any{
            "messageId": record.MessageId,
            "attempt":   record.Attributes["ApproximateReceiveCount"],
        })

        // Logger maintains context throughout the operation
        if err := processOrder(record.Body); err != nil {
            lambdaLog.Error("Failed to process order", err)
            return err
        }
    }
    return nil
}

HTTP Request Processing

log.AddHTTPRequest(logger.HTTPRequest{
    Method:  "GET",
    Path:    "/api/orders",
    Headers: map[string]string{"X-Correlation-Id": correlationId},
})

log.Info("Processing request", map[string]any{
    "messageId": messageId,
    "attempt":   attemptCount,
})

// Process the request...
response, err := processRequest()

log.AddHTTPResponse(logger.HTTPResponse{
    StatusCode: 200,
    Headers:    responseHeaders,
})

Advanced Features

Smart Error Handling

Errors are automatically serialized with full context, including the goroutine stack trace and the full error chain:

_, err := riskyOperation()
if err != nil {
    log.Error("Operation failed", err, map[string]any{
        "context": "additional-info",
    })
    // Logged fields include: error message, stack trace, error type, causes, and your context
}

Flexible Context Management

// Add user context that persists across all subsequent logs
log.AddUserContext(logger.User{
    ID:   "user-123",
    Role: "admin",
})

// Add telemetry for performance tracking
log.AddTelemetryFields(logger.TelemetryFields{
    Duration:  150,
    Namespace: "db-query",
})

// Add custom context for a specific log
log.Info("Payment processed", map[string]any{
    "amount":   99.99,
    "currency": "USD",
})

Correlation ID Management

// Set a specific correlation ID (also sets requestId and traceId)
log.SetCorrelationID("abc-123")

// Read the current correlation ID
id := log.CorrelationID()

// Generate a fresh correlation ID
log.ResetCorrelationID()

// Reset all context and generate new IDs
log.ResetContext()

Local Development Features

Pretty Printing

Pretty output is automatically enabled in local or CI environments (SST_DEV, IS_LOCAL, or GITHUB_ACTIONS):

prettyOn := true
log, _ := logger.New(logger.Options{
    PrettyPrint: &prettyOn, // Force enable for readable console output
})

Automatic Log Rotation

File logging is automatically enabled in local environments and can be configured explicitly:

fileOn := true
log, _ := logger.New(logger.Options{
    LogToFile: &fileOn,
    Rotation: &logger.RotationOptions{
        Path:           ".smooai-logs",
        FilenamePrefix: "app",
        Extension:      "log",
        Size:           "10M",  // Rotate at 10 MB
        Interval:       "1d",   // Daily rotation
        MaxFiles:       10,     // Keep 10 files
        MaxTotalSize:   "100M", // Total size limit
    },
})

API Reference

Logger Creation

import logger "github.com/SmooAI/logger/go/v4"

// With options
prettyOn := true
log, err := logger.New(logger.Options{
    Name:        "MyService",
    Level:       logger.LevelInfo,
    PrettyPrint: &prettyOn,
})

// With defaults
log := logger.Default()

Context Helpers

// HTTP context (also extracts X-Correlation-Id header automatically)
log.AddHTTPRequest(logger.HTTPRequest{
    Method:  "GET",
    Path:    "/api/users",
    Headers: map[string]string{"X-Correlation-Id": "abc-123"},
})

log.AddHTTPResponse(logger.HTTPResponse{
    StatusCode: 200,
    Headers:    responseHeaders,
})

// User context
log.AddUserContext(logger.User{
    ID:    "user-123",
    Email: "user@example.com",
    Role:  "admin",
})

// Telemetry and tracing
log.AddTelemetryFields(logger.TelemetryFields{
    RequestID: "req-456",
    TraceID:   "trace-789",
    Duration:  250,
    Namespace: "user-service",
    Service:   "api-gateway",
})

// Arbitrary custom context (merged into the "context" field)
log.AddContext(logger.Map{
    "customField": "value",
    "nested": logger.Map{
        "key": "value",
    },
})

// Set a single base-level key
log.AddBaseContextKey("region", "us-east-1")

// Set namespace
log.SetNamespace("custom-namespace")

// Reset all context and regenerate correlation IDs
log.ResetContext()

Lambda Helpers

lambdaLog := logger.NewLambdaLogger(log)

// Add Lambda invocation context (request ID, function ARN, Cognito identity)
lambdaLog.AddLambdaContext(ctx)

// Add Lambda environment variables (function name, version, region, memory)
lambdaLog.AddLambdaEnvironmentContext()

// Add API Gateway request context
lambdaLog.AddAPIGatewayContext(request)

// Add SQS record context (also sets correlation ID from message ID)
lambdaLog.AddSQSRecordContext(record)

// Strip verbose context when running locally
lambdaLog.SlimDownLocally()

Logging Methods

// Simple message
log.Info("User created successfully")

// With structured data (map[string]any args are merged into the "context" field)
log.Info("Processing request", map[string]any{
    "userId": "123",
    "action": "create",
})

// With error (stack trace and error chain captured automatically)
log.Error("Database connection failed", err)

// Combining message, error, and data
log.Error("Failed to create user", err, map[string]any{
    "userId":  "123",
    "attempt": 3,
})

// All log levels
log.Trace("Verbose detail")
log.Debug("Diagnostic info")
log.Info("Operational message")
log.Warn("Warning condition")
log.Error("Error condition", err)
log.Fatal("Critical failure", err)

Lifecycle

// Close flushes and closes the file writer (call on shutdown)
defer log.Close()

Configuration

Log Levels

• LevelTrace (10) - Detailed debugging information
• LevelDebug (20) - Diagnostic information
• LevelInfo (30) - General operational information
• LevelWarn (40) - Warning conditions
• LevelError (50) - Error conditions
• LevelFatal (60) - Critical failures

Log level can also be set via the LOG_LEVEL environment variable (trace, debug, info, warn, error, fatal).

Environment Variables

The logger respects these environment variables for automatic configuration:

• SST_DEV - Enables pretty printing and file logging in SST development
• IS_LOCAL - Enables pretty printing and file logging for local development
• IS_DEPLOYED_STAGE - When set to true, disables local-mode behaviour
• GITHUB_ACTIONS - Enables pretty printing in CI/CD
• LOG_LEVEL - Sets the minimum log level (default: info)

Built With

• Go 1.22+ - Static typing and first-class concurrency
• encoding/json - Standard library JSON serialization
• github.com/aws/aws-lambda-go - AWS Lambda context and event types
• github.com/google/uuid - Correlation ID generation
• Automatic log rotation with configurable size, interval, and retention

Related Packages

• @smooai/logger - TypeScript/JavaScript version
• smooai-logger (Python) - Python version
• smooai-logger (Rust) - Rust version

Development

Running tests

go test ./...

Building

go build ./...

Linting and Formatting

go vet ./...
gofmt -w .

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Contact

Brent Rager

• Email
• LinkedIn
• BlueSky

Smoo Github: https://github.com/SmooAI

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License

MIT © SmooAI