Lambda Function Construct¶

The LambdaFunctionConstruct provides a comprehensive, production-ready Lambda function with configurable OpenTelemetry support, IAM management, and environment configuration.

Features¶

OpenTelemetry Integration: Configurable AWS OpenTelemetry collector layer with version and architecture support
IAM Management: Automatic role and policy creation with CloudWatch Logs permissions
Environment Configuration: Easy environment variable management
Function URLs: Optional HTTP endpoint generation
SnapStart Support: Improved cold start performance for Java runtimes
Versioning & Aliases: Automatic version management with "live" alias
Lambda Permissions: Multi-target permission management (function, version, alias)

Basic Usage¶

using Amazon.CDK;
using LayeredCraft.Cdk.Constructs;
using LayeredCraft.Cdk.Constructs.Models;

public class MyStack : Stack
{
    public MyStack(Construct scope, string id, IStackProps props = null) : base(scope, id, props)
    {
        var lambda = new LambdaFunctionConstruct(this, "MyLambda", new LambdaFunctionConstructProps
        {
            FunctionName = "my-api",
            FunctionSuffix = "prod",
            AssetPath = "./lambda-deployment.zip",
            RoleName = "my-api-role",
            PolicyName = "my-api-policy",
            IncludeOtelLayer = true // Enable OpenTelemetry (disabled by default in v2.0+)
        });
    }
}

Configuration Properties¶

Required Properties¶

Property	Type	Description
`FunctionName`	`string`	Base name of the Lambda function
`FunctionSuffix`	`string`	Suffix appended to function name (e.g., "prod", "dev")
`AssetPath`	`string`	Path to Lambda deployment package
`RoleName`	`string`	Name of the IAM role
`PolicyName`	`string`	Name of the IAM policy

Optional Properties¶

Property	Type	Default	Description
`MemorySize`	`double`	`1024`	Memory allocation in MB
`TimeoutInSeconds`	`double`	`6`	Function timeout in seconds
`PolicyStatements`	`PolicyStatement[]`	`[]`	Additional IAM policy statements
`EnvironmentVariables`	`IDictionary<string, string>`	`{}`	Environment variables
`IncludeOtelLayer`	`bool`	`false`	Enable OpenTelemetry layer
`OtelLayerVersion`	`string`	`"0-117-0"`	OpenTelemetry layer version
`Architecture`	`string`	`"amd64"`	Lambda architecture (amd64/arm64)
`Permissions`	`List<LambdaPermission>`	`[]`	Lambda invocation permissions
`EnableSnapStart`	`bool`	`false`	Enable SnapStart for improved cold starts
`GenerateUrl`	`bool`	`false`	Generate Function URL for HTTP access

Advanced Examples¶

Lambda with DynamoDB Access¶

var dynamoPolicy = new PolicyStatement(new PolicyStatementProps
{
    Actions = ["dynamodb:GetItem", "dynamodb:PutItem", "dynamodb:Query"],
    Resources = ["arn:aws:dynamodb:us-east-1:123456789012:table/MyTable"],
    Effect = Effect.ALLOW
});

var lambda = new LambdaFunctionConstruct(this, "MyLambda", new LambdaFunctionConstructProps
{
    FunctionName = "my-api",
    FunctionSuffix = "prod",
    AssetPath = "./lambda-deployment.zip",
    RoleName = "my-api-role",
    PolicyName = "my-api-policy",
    PolicyStatements = [dynamoPolicy],
    EnvironmentVariables = new Dictionary<string, string>
    {
        { "TABLE_NAME", "MyTable" },
        { "AWS_REGION", "us-east-1" }
    }
});

Lambda with Function URL¶

var lambda = new LambdaFunctionConstruct(this, "MyLambda", new LambdaFunctionConstructProps
{
    FunctionName = "my-api",
    FunctionSuffix = "prod",
    AssetPath = "./lambda-deployment.zip",
    RoleName = "my-api-role",
    PolicyName = "my-api-policy",
    GenerateUrl = true, // Creates HTTP endpoint
    MemorySize = 2048,
    TimeoutInSeconds = 30
});

// Access the function URL domain
var functionUrl = lambda.LiveAliasFunctionUrlDomain;

Lambda with API Gateway Permissions¶

var apiPermission = new LambdaPermission
{
    Principal = "apigateway.amazonaws.com",
    Action = "lambda:InvokeFunction",
    SourceArn = "arn:aws:execute-api:us-east-1:123456789012:abcdef123/*"
};

var lambda = new LambdaFunctionConstruct(this, "MyLambda", new LambdaFunctionConstructProps
{
    FunctionName = "my-api",
    FunctionSuffix = "prod",
    AssetPath = "./lambda-deployment.zip",
    RoleName = "my-api-role",
    PolicyName = "my-api-policy",
    Permissions = [apiPermission]
});

Lambda with SnapStart¶

var lambda = new LambdaFunctionConstruct(this, "MyLambda", new LambdaFunctionConstructProps
{
    FunctionName = "my-api",
    FunctionSuffix = "prod",
    AssetPath = "./lambda-deployment.zip",
    RoleName = "my-api-role",
    PolicyName = "my-api-policy",
    EnableSnapStart = true // Improves cold start performance
});

Lambda with OpenTelemetry Configuration¶

var lambda = new LambdaFunctionConstruct(this, "MyLambda", new LambdaFunctionConstructProps
{
    FunctionName = "my-api",
    FunctionSuffix = "prod",
    AssetPath = "./lambda-deployment.zip",
    RoleName = "my-api-role",
    PolicyName = "my-api-policy",
    IncludeOtelLayer = true,           // Enable OpenTelemetry layer
    Architecture = "arm64",            // Use ARM64 architecture
    OtelLayerVersion = "0-117-0"       // Specify OTEL layer version
});

Breaking Change in v2.0.0

Starting with version 2.0.0, the OpenTelemetry layer is disabled by default. You must explicitly set IncludeOtelLayer = true to enable it. This change allows for better control over observability costs and layer dependencies.

Public Properties¶

LambdaFunction¶

Access the underlying CDK Lambda function for advanced configuration:

var lambda = new LambdaFunctionConstruct(this, "MyLambda", props);
var underlyingFunction = lambda.LambdaFunction;

// Add additional configuration
underlyingFunction.AddEnvironment("CUSTOM_VAR", "value");

LiveAliasFunctionUrlDomain¶

Get the domain of the Function URL (if enabled):

var lambda = new LambdaFunctionConstruct(this, "MyLambda", new LambdaFunctionConstructProps
{
    // ... other props
    GenerateUrl = true
});

var domain = lambda.LiveAliasFunctionUrlDomain; // Returns the domain string

Runtime Configuration¶

The Lambda functions use the following runtime configuration:

Runtime Details

Runtime: PROVIDED_AL2023 (Amazon Linux 2023)
Handler: bootstrap (for custom runtimes)
Architecture: Configurable (amd64/arm64, default: amd64)
Log Retention: 2 weeks
OpenTelemetry Layer: Configurable AWS managed layer (disabled by default in v2.0+)

IAM Permissions¶

The construct automatically creates:

CloudWatch Logs Permissions:
logs:CreateLogStream
logs:CreateLogGroup
logs:TagResource
logs:PutLogEvents
Custom Policy Statements: Any additional policies you provide
Lambda Permissions: Applied to function, version, and alias

Versioning Strategy¶

Creates a new version on every deployment
Maintains a "live" alias pointing to the latest version
Versions have RemovalPolicy.RETAIN to prevent deletion

Testing¶

See the Testing Guide for comprehensive testing utilities and patterns specific to the Lambda Function construct.

Examples¶

For more real-world examples, see the Examples section.