FsCDK is an F# library for the AWS Cloud Development Kit (CDK), enabling you to define cloud infrastructure using F#'s type safety and functional programming style. It provides F#-friendly builders on top of AWS CDK constructs, so you can compose infrastructure in a concise, declarative way to build reliable and maintainable cloud infrastructure as code.

• Type-Safe Infrastructure: Leverage F#'s strong type system to catch configuration errors at compile time
• Functional-First Approach: Use F#'s functional programming features to create reusable and composable infrastructure components
• Native AWS CDK Integration: Full access to AWS CDK constructs and patterns with F#-friendly APIs
• Immutable Infrastructure: Define your infrastructure using immutable constructs, promoting reliable and predictable deployments
• IDE Support: Excellent tooling support with type hints and IntelliSense in your favorite F# IDE

1. Install the package:

dotnet add package FsCDK

2. Define a simple stack with a bucket and a Lambda function using a single builder API:

open Amazon.CDK
open Amazon.CDK.AWS.S3
open Amazon.CDK.AWS.Lambda
open FsCDK

let config = Config.get () // e.g., reads AWS account and region from env

stack "MyFirstStack" {
    app {
        context "environment" "production"
        context "feature-flag" true
        context "version" "1.2.3"
    }

    environment {
        account config.Account
        region config.Region
    }

    stackProps {
        stackEnv
        description "My first FsCDK stack"
    }

    // S3 bucket
    bucket "MyBucket" {
        versioned true
        encryption BucketEncryption.S3_MANAGED
        blockPublicAccess BlockPublicAccess.BLOCK_ALL
    }

    // Lambda function
    lambda "HelloFunction" {
        runtime Runtime.DOTNET_8
        handler "Playground::Playground.Handlers::sayHello"
        code "../Playground/bin/Release/net8.0/publish"
        timeout 30.0
        memory 256
        description "A simple hello world lambda"
    }
}

3. Synthesize and deploy:

cdk synth   # Review the generated CloudFormation template
cdk deploy  # Deploy to AWS

For detailed documentation, examples, and best practices, visit our Documentation Site.

Notes:

• Defaults and configuration come from AWS CDK and your code; review the synthesized template to verify settings meet your needs.
• You can mix FsCDK builders with direct AWS CDK constructs anywhere you need lower-level control.

FsCDK provides F# builders for 30+ AWS services across all major categories:

• Custom Resources - Define custom CloudFormation resources
• Lambda Powertools - Production-ready observability for Lambda functions
• Grants - Simplified IAM permission management between resources
• Tags - Resource tagging across stacks
• Production-Safe Defaults - Security and reliability best practices built-in

• See the repository's examples and samples (if available in the tree) for additional patterns such as API gateways, queues, and databases.

Here's a complex example serverless web application architecture you could build with FsCDK:

graph TB
    User([User])
    CF[CloudFront CDN]
    S3[S3 Bucket<br/>Static Website]
    R53[Route53<br/>DNS]
    ALB[Application Load Balancer]
    APIGW[API Gateway<br/>REST API]
    COG[Cognito<br/>User Pool]
    
    L1[Lambda Function<br/>API Handler]
    L2[Lambda Function<br/>Background Processor]
    L3[Lambda Function<br/>Event Handler]
    
    DDB[(DynamoDB<br/>NoSQL Table)]
    RDS[(RDS PostgreSQL<br/>Database)]
    
    SQS[SQS Queue]
    DLQ[SQS Dead Letter Queue]
    SNS[SNS Topic<br/>Notifications]
    EB[EventBridge<br/>Event Bus]
    
    SF[Step Functions<br/>Workflow]
    KIN[Kinesis Stream<br/>Data Stream]
    
    CW[CloudWatch<br/>Logs & Metrics]
    KMS[KMS Key<br/>Encryption]
    SEC[Secrets Manager]
    
    VPC[VPC Network]
    SG[Security Groups]
    
    User -->|HTTPS| R53
    R53 --> CF
    CF --> S3
    CF --> ALB
    ALB --> L1
    
    User -->|API Calls| APIGW
    APIGW -->|Authenticate| COG
    APIGW --> L1
    
    L1 -->|Read/Write| DDB
    L1 -->|Query| RDS
    L1 -->|Send Message| SQS
    L1 -->|Publish Event| SNS
    L1 -->|Emit Event| EB
    
    SQS -->|Failed Messages| DLQ
    SQS -->|Trigger| L2
    SNS -->|Subscribe| SQS
    EB -->|Rule Match| L3
    
    L2 -->|Process| DDB
    L3 -->|Write| KIN
    
    L1 -.->|Start Execution| SF
    SF -.->|Orchestrate| L2
    
    L1 -.->|Log| CW
    L2 -.->|Log| CW
    L3 -.->|Log| CW
    
    DDB -.->|Encrypted by| KMS
    RDS -.->|Encrypted by| KMS
    L1 -.->|Get Credentials| SEC
    
    RDS -.->|Inside| VPC
    L1 -.->|Access via| SG
    
    style User fill:#e1f5ff
    style CF fill:#ff9900
    style S3 fill:#569a31
    style APIGW fill:#ff4f8b
    style L1 fill:#ff9900
    style L2 fill:#ff9900
    style L3 fill:#ff9900
    style DDB fill:#4053d6
    style RDS fill:#4053d6
    style SQS fill:#ff4f8b
    style SNS fill:#ff4f8b
    style CW fill:#ff4f8b
    style KMS fill:#dd344c
    style VPC fill:#248814

Architecture Highlights:

• Frontend: CloudFront CDN serving an S3-hosted static website with Route53 DNS
• API Layer: API Gateway with Cognito authentication, routing to Lambda functions
• Compute: Multiple Lambda functions handling different concerns (API, background jobs, events)
• Storage: DynamoDB for NoSQL data and RDS for relational data
• Messaging: SQS queues for async processing, SNS for pub/sub, EventBridge for event routing
• Streaming: Kinesis for real-time data ingestion
• Orchestration: Step Functions coordinating complex workflows
• Security: KMS for encryption, Secrets Manager for credentials, Security Groups for network control
• Monitoring: CloudWatch for centralized logging and metrics
• Networking: VPC for isolated network environment

All of these resources can be defined using FsCDK's type-safe computation expression builders!

Contributions are welcome! Whether it's:

• Reporting a bug
• Submitting a fix
• Proposing new features

Please check out our Contributing Guide for guidelines.

This project is licensed under the MIT License - see the LICENSE file for details.