What is deployment of an application?

Deployment (or deployment) is the process of delivering, installing, and configuring an application on a target environment (servers, cloud platforms, etc.) to make it accessible to end-users or other systems.

Key stages of deployment may include:

• Build: Creating executable artifacts (modules, compiled code). In Node.js, this could be simply copying source code, or transpiling (e.g., from TypeScript) and packaging.
• Testing: Verifying the functionality of artifacts at various levels (unit, integration).
• Packaging: Creating a distribution of the application (e.g., Docker image, archive).
• Deployment: Copying the packaged application to the target environment.
• Configuration: Setting environment-specific parameters (environment variables, database settings).
• Runtime: Starting application processes.
• Monitoring: Observing the application's operation after deployment.

In the context of Node.js, deployment often includes:

• Installing dependencies using npm install or yarn install.
• Configuring a web server (e.g., Nginx or Caddy) to proxy requests to the Node.js process.
• Using process managers like PM2 or Forever to maintain the application's lifecycle and automatically restart in case of failures.
• Setting environment variables for different environments (development, staging, production).

Examples of deployment environments for Node.js:

• Virtual machines (AWS EC2, DigitalOcean Droplets).
• Platform as a Service (Heroku, Render, Vercel).
• Container platforms (Docker, Kubernetes).
• Function as a Service (AWS Lambda, Google Cloud Functions).