lambda

DynamORM Lambda Example

This example demonstrates how to use DynamORM in AWS Lambda with multi-account support and optimized cold starts.

Features

• ✅ Optimized for Lambda cold starts (< 100ms)
• ✅ Multi-account support with AssumeRole
• ✅ Connection reuse across warm invocations
• ✅ Lambda timeout handling
• ✅ Pre-registered models for faster initialization

Setup

1. Environment Variables

Configure these environment variables in your Lambda function:

# Base configuration
AWS_REGION=us-east-1

# Partner 1 configuration
PARTNER1_ROLE_ARN=arn:aws:iam::123456789012:role/DynamORMPartner1Role
PARTNER1_EXTERNAL_ID=unique-external-id-partner1
PARTNER1_REGION=us-east-1

# Partner 2 configuration
PARTNER2_ROLE_ARN=arn:aws:iam::987654321098:role/DynamORMPartner2Role
PARTNER2_EXTERNAL_ID=unique-external-id-partner2
PARTNER2_REGION=us-west-2

2. IAM Roles

Create cross-account roles for each partner with this trust policy:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::YOUR_ACCOUNT_ID:root"
      },
      "Action": "sts:AssumeRole",
      "Condition": {
        "StringEquals": {
          "sts:ExternalId": "unique-external-id-partner1"
        }
      }
    }
  ]
}

3. Lambda Function Permissions

Your Lambda execution role needs:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "dynamodb:*"
      ],
      "Resource": "arn:aws:dynamodb:*:*:table/payments*"
    },
    {
      "Effect": "Allow",
      "Action": [
        "sts:AssumeRole"
      ],
      "Resource": [
        "arn:aws:iam::*:role/DynamORMPartner*"
      ]
    }
  ]
}

Building and Deployment

Build for Lambda

# Build the Lambda function
GOOS=linux GOARCH=amd64 go build -tags lambda -ldflags="-s -w" -o bootstrap main.go

# Create deployment package
zip function.zip bootstrap

Deploy with AWS CLI

# Create function
aws lambda create-function \
  --function-name dynamorm-example \
  --runtime provided.al2 \
  --role arn:aws:iam::YOUR_ACCOUNT:role/lambda-execution-role \
  --handler bootstrap \
  --zip-file fileb://function.zip \
  --memory-size 512 \
  --timeout 30 \
  --environment Variables="{
    PARTNER1_ROLE_ARN=arn:aws:iam::123456789012:role/DynamORMPartner1Role,
    PARTNER1_EXTERNAL_ID=unique-external-id-partner1,
    PARTNER1_REGION=us-east-1
  }"

# Update function code
aws lambda update-function-code \
  --function-name dynamorm-example \
  --zip-file fileb://function.zip

Usage

Request Format

{
  "partnerId": "partner1",
  "action": "createPayment",
  "data": {
    "amount": 100.50,
    "currency": "USD"
  }
}

Supported Actions

1. Get Payment

{
  "partnerId": "partner1",
  "action": "getPayment",
  "data": {
    "paymentId": "pay_1234567890"
  }
}

1. Create Payment

{
  "partnerId": "partner1",
  "action": "createPayment",
  "data": {
    "amount": 100.50,
    "currency": "USD"
  }
}

Response Format

Success response:

{
  "success": true,
  "data": {
    "id": "pay_1234567890",
    "partnerId": "partner1",
    "amount": 10050,
    "currency": "USD",
    "status": "pending",
    "createdAt": "2024-01-01T00:00:00Z",
    "updatedAt": "2024-01-01T00:00:00Z"
  }
}

Error response:

{
  "success": false,
  "error": "payment not found"
}

Performance Optimization

Cold Start Optimization

The example uses several techniques to minimize cold starts:

1. Global DB Instance: Reuses connections across warm invocations
2. Pre-registered Models: Models are registered during init
3. Optimized HTTP Client: Configured for Lambda environment
4. Connection Pooling: Tuned for Lambda memory constraints

Memory Configuration

Adjust Lambda memory based on your needs:

• 256 MB: Basic operations, minimal concurrent requests
• 512 MB: Standard operations, moderate load
• 1024 MB: Complex queries, high throughput
• 3008 MB: Maximum performance, heavy workloads

Monitoring

Enable X-Ray tracing for performance insights:

aws lambda update-function-configuration \
  --function-name dynamorm-example \
  --tracing-config Mode=Active

Testing

Local Testing

# Install SAM CLI
brew install aws-sam-cli

# Run locally
sam local start-lambda

# Invoke function
aws lambda invoke \
  --function-name dynamorm-example \
  --endpoint-url http://localhost:3001 \
  --payload '{"partnerId":"partner1","action":"getPayment","data":{"paymentId":"test"}}' \
  response.json

Integration Testing

# Run integration tests
go test -v ./examples/lambda/...

Troubleshooting

Common Issues

1. Timeout Errors

   • Increase Lambda timeout
   • Check DynamoDB throttling
   • Verify network configuration

2. Permission Errors

   • Check IAM roles and policies
   • Verify external ID matches
   • Ensure trust relationships are correct

3. Cold Start Performance

   • Pre-warm Lambda with scheduled events
   • Increase memory allocation
   • Enable provisioned concurrency

Debug Logging

Enable debug logs:

os.Setenv("DYNAMORM_DEBUG", "true")

Cost Optimization

1. Use On-Demand Tables: Better for unpredictable workloads
2. Enable Auto-Scaling: For provisioned capacity
3. Batch Operations: Reduce API calls
4. Efficient Queries: Use indexes properly

Next Steps

• Implement caching with ElastiCache
• Add API Gateway integration
• Set up CI/CD pipeline
• Configure CloudWatch alarms