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add sam template
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‎Examples/ServiceLifecycle/.gitignore‎

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DerivedData/
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.swiftpm/configuration/registries.json
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.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
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.netrc
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.netrc
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.amazonq

‎Examples/ServiceLifecycle/README.md‎

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# ServiceLifecycle Lambda with PostgreSQL
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This example demonstrates a Swift Lambda function that uses ServiceLifecycle to manage a PostgreSQL connection. The function connects to a publicly accessible RDS PostgreSQL database and queries user data.
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## Architecture
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- **Swift Lambda Function**: Uses ServiceLifecycle to manage PostgreSQL client lifecycle
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- **PostgreSQL RDS**: Publicly accessible database instance
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- **API Gateway**: HTTP endpoint to invoke the Lambda function
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- **VPC**: Custom VPC with public subnets for RDS and Lambda
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## Prerequisites
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- Swift 6.x toolchain
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- Docker (for building Lambda functions)
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- AWS CLI configured with appropriate permissions
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- SAM CLI installed
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## Database Schema
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The Lambda function expects a `users` table with the following structure:
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```sql
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CREATE TABLE users (
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id SERIAL PRIMARY KEY,
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username VARCHAR(50) NOT NULL
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);
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-- Insert some sample data
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INSERT INTO users (username) VALUES ('alice'), ('bob'), ('charlie');
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```
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## Deployment
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### Option 1: Using the deployment script
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```bash
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./deploy.sh
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```
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### Option 2: Manual deployment
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1. **Build the Lambda function:**
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```bash
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swift package archive --allow-network-connections docker
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```
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2. **Deploy with SAM:**
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```bash
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sam deploy
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```
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### Option 3: Deploy with custom parameters
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```bash
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sam deploy --parameter-overrides \
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DBUsername=myuser \
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DBPassword=MySecurePassword123! \
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DBName=mydatabase
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```
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## Getting Connection Details
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After deployment, get the database connection details:
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```bash
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aws cloudformation describe-stacks \
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--stack-name servicelifecycle-stack \
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--query 'Stacks[0].Outputs'
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```
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The output will include:
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- **DatabaseEndpoint**: Hostname to connect to
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- **DatabasePort**: Port number (5432)
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- **DatabaseName**: Database name
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- **DatabaseUsername**: Username
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- **DatabasePassword**: Password
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- **DatabaseConnectionString**: Complete connection string
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## Connecting to the Database
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### Using psql
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```bash
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# Get the connection details from CloudFormation outputs
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DB_HOST=$(aws cloudformation describe-stacks --stack-name servicelifecycle-stack --query 'Stacks[0].Outputs[?OutputKey==`DatabaseEndpoint`].OutputValue' --output text)
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DB_USER=$(aws cloudformation describe-stacks --stack-name servicelifecycle-stack --query 'Stacks[0].Outputs[?OutputKey==`DatabaseUsername`].OutputValue' --output text)
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DB_NAME=$(aws cloudformation describe-stacks --stack-name servicelifecycle-stack --query 'Stacks[0].Outputs[?OutputKey==`DatabaseName`].OutputValue' --output text)
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DB_PASSWORD=$(aws cloudformation describe-stacks --stack-name servicelifecycle-stack --query 'Stacks[0].Outputs[?OutputKey==`DatabasePassword`].OutputValue' --output text)
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# Connect with psql
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psql -h $DB_HOST -U $DB_USER -d $DB_NAME
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```
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### Using connection string
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```bash
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# Get the complete connection string
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CONNECTION_STRING=$(aws cloudformation describe-stacks --stack-name servicelifecycle-stack --query 'Stacks[0].Outputs[?OutputKey==`DatabaseConnectionString`].OutputValue' --output text)
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# Connect with psql
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psql "$CONNECTION_STRING"
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```
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## Setting up the Database
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Once connected to the database, create the required table and sample data:
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```sql
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-- Create the users table
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CREATE TABLE users (
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id SERIAL PRIMARY KEY,
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username VARCHAR(50) NOT NULL
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);
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-- Insert sample data
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INSERT INTO users (username) VALUES
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('alice'),
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('bob'),
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('charlie'),
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('diana'),
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('eve');
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```
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## Testing the Lambda Function
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Get the API Gateway endpoint and test the function:
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```bash
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# Get the API endpoint
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API_ENDPOINT=$(aws cloudformation describe-stacks --stack-name servicelifecycle-stack --query 'Stacks[0].Outputs[?OutputKey==`APIGatewayEndpoint`].OutputValue' --output text)
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# Test the function
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curl "$API_ENDPOINT"
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```
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The function will:
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1. Connect to the PostgreSQL database
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2. Query the `users` table
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3. Log the results
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4. Return "Done"
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## Monitoring
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Check the Lambda function logs:
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```bash
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sam logs -n ServiceLifecycleLambda --stack-name servicelifecycle-stack --tail
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```
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## Security Considerations
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⚠️ **Important**: This example creates a publicly accessible PostgreSQL database for demonstration purposes. In production:
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1. **Use private subnets** and VPC endpoints
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2. **Implement proper authentication** (IAM database authentication)
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3. **Use AWS Secrets Manager** for password management
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4. **Enable encryption** at rest and in transit
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5. **Configure proper security groups** with minimal required access
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6. **Enable database logging** and monitoring
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## Cost Optimization
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The template uses:
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- `db.t3.micro` instance (eligible for free tier)
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- Minimal storage allocation (20GB)
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- No Multi-AZ deployment
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- No automated backups
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For production workloads, adjust these settings based on your requirements.
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## Cleanup
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To delete all resources:
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```bash
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sam delete --stack-name servicelifecycle-stack
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```
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## Troubleshooting
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### Lambda can't connect to database
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1. Check security groups allow traffic on port 5432
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2. Verify the database is publicly accessible
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3. Check VPC configuration and routing
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4. Verify database credentials in environment variables
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### Database connection timeout
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The PostgreSQL client may hang if the database is unreachable. This is a known issue with PostgresNIO. Ensure:
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1. Database is running and accessible
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2. Security groups are properly configured
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3. Network connectivity is available
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### Build failures
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Ensure you have:
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1. Swift 6.x toolchain installed
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2. Docker running
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3. Proper network connectivity for downloading dependencies
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## Files
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- `template.yaml`: SAM template defining all AWS resources
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- `samconfig.toml`: SAM configuration file
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- `deploy.sh`: Deployment script
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- `Sources/Lambda.swift`: Swift Lambda function code
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- `Sources/RootRDSCert.swift`: RDS root certificate for SSL connections
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- `Package.swift`: Swift package definition

‎Examples/ServiceLifecycle/Sources/Lambda.swift‎

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struct LambdaFunction {
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static func main() async throws {
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LambdaFunction().main()
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try await LambdaFunction().main()
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}
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private let pgClient: PostgresClient
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private var logger: Logger
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private init() throws {
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self.logger = Logger(label: "ServiceLifecycleExample")
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logger.logLevel = .trace
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self.pgClient = try preparePostgresClient(
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self.pgClient = try LambdaFunction.preparePostgresClient(
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host: Lambda.env("DB_HOST") ?? "localhost",
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user: Lambda.env("DB_USER") ?? "postgres",
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password: Lambda.env("DB_PASSWORD") ?? "secret",
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dbName: Lambda.env("DB_NAME") ?? "test"
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)
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}
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private func main() {
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private func main() async throws {
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/// Instantiate LambdaRuntime with a closure handler implementing the business logic of the Lambda function
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let runtime = LambdaRuntime(logger: logger, body: handler)
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// Instantiate LambdaRuntime with a handler implementing the business logic of the Lambda function
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// ok when https://github.com/swift-server/swift-aws-lambda-runtime/pull/523 will be merged
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//let runtime = LambdaRuntime(logger: logger, body: handler)
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let runtime = LambdaRuntime(body: handler)
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/// Use ServiceLifecycle to manage the initialization and termination
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/// of the PGClient together with the LambdaRuntime
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let serviceGroup = ServiceGroup(
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services: [pgClient, runtime],
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gracefulShutdownSignals: [.sigterm, .sigint], // add SIGINT for CTRL+C in local testing
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// cancellationSignals: [.sigint],
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// gracefulShutdownSignals: [.sigterm, .sigint], // add SIGINT for CTRL+C in local testing
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cancellationSignals: [.sigint],
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logger: logger
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)
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try await serviceGroup.run()
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}
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private func handler(event: String, context: LambdaContext) -> String {
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private func handler(event: String, context: LambdaContext) async -> String {
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do {
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// Use initialized service within the handler
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// IMPORTANT - CURRENTLY WHEN THERE IS AN ERROR, THIS CALL HANGS WHEN DB IS NOT REACHABLE
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} catch {
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logger.error("PG Error: \(error)")
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}
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return "Done"
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}
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private func preparePostgresClient(
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private static func preparePostgresClient(
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host: String,
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user: String,
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password: String,

‎Examples/ServiceLifecycle/deploy.sh‎

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#!/bin/bash
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# ServiceLifecycle Lambda Deployment Script
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set -e
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echo "🚀 Building and deploying ServiceLifecycle Lambda with PostgreSQL..."
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# Build the Lambda function
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echo "📦 Building Swift Lambda function..."
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swift package --disable-sandbox archive --allow-network-connections docker
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# Deploy with SAM
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echo "🌩️ Deploying with SAM..."
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sam deploy
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echo "✅ Deployment complete!"
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echo ""
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echo "📋 To get the database connection details, run:"
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echo "aws cloudformation describe-stacks --stack-name servicelifecycle-stack --query 'Stacks[0].Outputs'"
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echo ""
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echo "🧪 To test the Lambda function:"
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echo "curl \$(aws cloudformation describe-stacks --stack-name servicelifecycle-stack --query 'Stacks[0].Outputs[?OutputKey==\`APIGatewayEndpoint\`].OutputValue' --output text)"

‎Examples/ServiceLifecycle/samconfig.toml‎

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# SAM configuration file for ServiceLifecycle example
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version = 0.1
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[default.global.parameters]
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stack_name = "servicelifecycle-stack"
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[default.build.parameters]
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cached = true
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parallel = true
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[default.deploy.parameters]
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capabilities = "CAPABILITY_IAM"
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confirm_changeset = true
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resolve_s3 = true
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s3_prefix = "servicelifecycle"
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region = "us-east-1"
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image_repositories = []
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[default.package.parameters]
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resolve_s3 = true
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[default.sync.parameters]
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watch = true
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[default.local_start_api.parameters]
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warm_containers = "EAGER"
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[default.local_start_lambda.parameters]
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warm_containers = "EAGER"

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