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Serverless Express Application

docs/scf/examples/express.md

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Serverless Express Application

This example demonstrates how to build and deploy a simple Express-based web application using the Serverless Container Framework (SCF). The application sets up basic routes—including a health check, static file delivery, and a fallback 404 page—with minimal configuration. The Serverless Container Framework enables this application to be deployed to either AWS Lambda or AWS ECS Fargate without rearchitecting.

Features

  • Express Framework:
    Leverages Express for routing and middleware handling.
  • Static File Serving:
    Serves static assets from a dedicated public directory.
  • Health Check Endpoint:
    Provides a simple /health route for monitoring application health.
  • Flexible Compute Options:
    Easily switch between AWS Lambda and AWS Fargate ECS deployments via SCF configuration.

Prerequisites

Before getting started, make sure you have:

  • Docker: Install and start Docker Desktop. (Get Docker)
  • Serverless Framework: Install globally:
    bash
    npm i -g serverless
  • Node.js & npm: Ensure you have a recent Node.js LTS version installed.
  • AWS Credentials: Properly configure your AWS credentials (via environment variables or AWS profiles) to allow SCF to provision and update AWS resources.

For more information on setting up AWS credentials, see the SCF Getting Started guide.

Configuration

At the project root, the serverless.containers.yml file defines the SCF configuration:

yaml
name: express

deployment:
  type: [email protected]

containers:
  service:
    src: ./service
    routing:
      pathPattern: /*
      pathHealthCheck: /health
    environment:
      HELLO: world
    compute:
      type: awsLambda # or awsFargateEcs

This configuration sets:

  • Project Namespace: The project name (express) is used as a namespace in your AWS account.
  • Deployment Settings: Configures networking (ALB, VPC, API Gateway) via the AWS API deployment type.
  • Container Details:
    • The source code is located in the ./service directory.
    • A catch-all routing rule (/*) is used with a dedicated health check endpoint (/health).
    • An environment variable (HELLO) is provided.
    • The compute type is set to awsLambda by default (switchable to awsFargateEcs as needed).

For more details on SCF configuration options, see the SCF Configuration documentation.

Project Structure

A typical project structure for this Express example:

example-express/
├── serverless.containers.yml      # SCF configuration file
└── service/
    ├── package.json                # Node.js project configuration and dependencies
    └── src/
        ├── index.js                # Main Express application entrypoint
        └── public/                 # Static assets (HTML, CSS, images, etc.)

Development

Serverless Container Framework provides a local development mode that emulates AWS routing and compute environments, including AWS Application Load Balancer emulation:

bash
serverless dev

This will automatically start everything and set up hot reloading.

For more information on local development with SCF, see the SCF Development documentation.

Deployment

Deploy your Express application to AWS by running:

bash
serverless deploy

During deployment, SCF builds the container image (using the provided multi-stage Dockerfile) and provisions the necessary AWS resources (ALB, VPC, Lambda function or ECS Fargate service).

For more details on deployment options and processes, see the SCF Deployment documentation.

Integrating with other resources

Serverless Container Framework supports the Serverless Framework Variables system to reference infrastructure details, secrets, and more from various sources:

yaml
containers:
  service:
    environment:
      # Simple static value
      SERVICE_NAME: express-service

      # Environment variable reference
      NODE_ENV: ${env:NODE_ENV}

      # AWS Systems Manager Parameter Store reference
      DATABASE_URL: ${aws:ssm:/path/to/database/url}

      # AWS Secrets Manager reference
      DATABASE_PASSWORD: ${aws:secretsmanager:ExpressDbSecret.password}

      # HashiCorp Vault reference
      API_SECRET: ${vault:secret/data/api/credentials.secret}

      # HashiCorp Terraform state reference
      REDIS_ENDPOINT: ${terraform:outputs:redis_endpoint}

      # S3 bucket value reference
      CONFIG_JSON: ${aws:s3:config-bucket/express-config.json}

      # CloudFormation stack output reference
      VPC_ID: ${aws:cf:networking-stack.VpcIdOutput}

For more details on using variables, see the Serverless Framework Variables documentation.

Cleanup

To remove deployed AWS resources when they are no longer needed:

bash
serverless remove --force --all

Additional Resources