supervisor
A supervisor script for Node.js that restarts programs when they crash or when JavaScript files change.
What is supervisor?
node-supervisor is a command-line tool for Node.js that supervises and automatically restarts your application when it crashes or when source code files change. It solves the problem of manually restarting Node.js servers during development and ensures applications remain running in production despite unexpected failures.
Node.js developers who need a simple, reliable way to keep their applications running continuously, especially during development with frequent code changes or in production environments where uptime is critical.
Developers choose node-supervisor for its minimal setup, no required code changes, and flexibility in monitoring files and managing restarts, making it a lightweight alternative to more complex process managers.
Overview
node-supervisor is a lightweight process supervisor for Node.js applications. It monitors your program and automatically restarts it if it crashes, and can also restart it when changes to JavaScript files are detected, enabling hot-code reloading behavior without requiring a complex module system overhaul.
Key Features
- Automatic Restart on Crash — Restarts the supervised program if it exits unexpectedly, ensuring continuous operation.
- File Change Detection — Watches specified directories and files for changes, triggering restarts to apply code updates.
- Configurable Watch/Ignore — Allows customizing which folders and file extensions to monitor or ignore.
- Flexible Execution — Supports running programs with different executables (e.g., Node, CoffeeScript) and debugging flags.
- Interactive Control — Provides commands like
rsto manually restart the process without file changes.
Philosophy
node-supervisor focuses on simplicity and reliability, offering a straightforward way to manage Node.js processes without introducing complex dependencies or requiring changes to your application's architecture.
Use Cases
Best For
- Automatically restarting Node.js servers after code changes during development
- Ensuring Node.js applications stay running after crashes in production
- Implementing hot-reload functionality without modifying application code
- Monitoring specific directories for changes in large projects
- Debugging Node.js applications with automatic restarts on file saves
- Running Node.js scripts that need continuous execution with crash recovery
Not Ideal For
- Projects requiring advanced process management features like clustering, load balancing, or monitoring dashboards
- Development teams using modern frameworks with built-in hot-reload (e.g., Next.js, NestJS dev servers)
- Production environments needing zero-downtime deployments or graceful shutdown handling beyond simple restarts
- Applications with complex state management that could be disrupted by sudden, ungraceful restarts
Pros & Cons
Pros
Immediately restarts the application if it crashes, ensuring continuous operation without manual intervention, as highlighted in the 'Automatic Restart on Crash' feature.
Watches for file changes and restarts the app, enabling seamless code updates during development without modifying application code, per the 'File Change Detection' capability.
Requires no changes to your Node.js application architecture, making it easy to integrate into existing projects, as stated in the philosophy of simplicity.
Supports running programs with different executables like Node or CoffeeScript and includes debugging flags, offering versatility for various development needs, as shown in the -x and --debug options.
Cons
Lacks advanced production-ready features such as logging aggregation, process clustering, or health checks, which are essential for large-scale deployments compared to tools like PM2.
Can cause high CPU load on systems with many watched files, especially on Windows, as indicated by the --force-watch option intended to mitigate this performance issue.
Does not provide detailed metrics or dashboards for monitoring application performance or restart history, relying solely on basic command-line output for feedback.
Frequently Asked Questions
Related Projects
PM2Node.js Production Process Manager with a built-in Load Balancer.
nodemonMonitor for any changes in your node.js application and automatically restart the server - perfect for development
Phusion PassengerA fast and robust web server and application server for Ruby, Python and Node.js
node-windowsWindows support for Node.JS scripts (daemons, eventlog, UAC, etc).
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