blockaid

Blockaid is an npm CLI tool (node.js) that allows you to require that a port is listening, or not listening, before taking an action. It also allows you to kill whatever is found listening on a port before taking an action.

Example usage

If you use package.json scripts to start a server, you might have configured something like:

(package.json)

"scripts": {
  "dev": "nodemon server.js"
}

If server.js depends on another service (e.g. a mysql database running on port 3306), you could require that port 3306 is running first, like so:

"scripts": {
  "dev": "blockaid -r mysql:3306 && nodemon server.js"
}

In this example, if port 3306 is not running, then an easy-to-understand error message will be printed with the failure to run server.js:

$ npm run dev
mysql is required, but is not listening on port 3306.

You can also use an environment variable, such as PORT, rather than a concrete port number. Here, we kill an existing listening process on PORT before starting the server:

"scripts": {
  "dev": "PORT=3000 blockaid -k service:PORT && nodemon server.js"
}

The shell return value will be "0" (indicating success) or "1" (indicating failure to meet the requirement specified).

Instructions

>>> blockaid : Require that a port is listening, not listening, or kill whatever is found listening.


  -r, --require-listening PROGRAM_NAME:PORT

    Require that a process is listening at PORT; PROGRAM_NAME is used for error messages


  -x, --require-not-listening PROGRAM_NAME:PORT

    Require that a process is NOT listening at PORT; PROGRAM_NAME is used for error messages


  -k, --kill-if-listening PROGRAM_NAME:PORT

    If a process is listening at PORT, kill it; PROGRAM_NAME is used for console message