wait-for-tcp-port

Wait for tcp port is a promise based library for waiting for one/more hosts/ports to become available. The waitForPort function checks only if the ports are opened and doesn't try to establish connection, that decrease the waiting time. By default it uses netcat utility for network discovery.

Installation

npm install --save wait-for-tcp-port

Examples

Waiting for a list of hosts/ports to be available

import waitForPort from 'wait-for-tcp-port';

const resources = ['example.com:80','example.com:443']

waitForPort({
  resources:resources,
  timeout: 40000,
  method: 'nmap'
}).then(function(res) {
  console.log('Wait for port result',res)
})
.catch(function(err) {
  console.error(err)
})

Output

Wait for port result { errors: 0,
  servers: 
   [ { ip: 'example.com', port: '80', tries: 1, status: 'open' },
     { ip: 'example.com', port: '443', tries: 1, status: 'open' } ] }

API

async waitForPort(options)

• options is an object consisting of
  • resources is an array consisting of the list of the ports to check, in the format 'host:port'
  • timeout - the maximum time to wait for the open ports in milliseconds. Default value is 120000(2 minutes)
  • interval - the interval for scanning the ports in milliseconds. Defalut value is 10000(every 10 seconds)
  • method - the utility used for checking the port status. Available values are : 'netcat','nmap'. If not specified, the netcat utility will be used by default.
  • portStatusFunction - a custom function to be used for checking the availability of the ports.

Return value

Returns an object

• errors indicates the number of instances for which errors occurred while scanning the ports
• servers an array of objects corresponding to each instance
  • ip the ip or dns of the server.
  • port the port checked to be opened.
  • tries the number of tries to scan the ports. This field is used in tests.
  • status can be 'open' or 'error'.
  • error is the error that occurred. This field is present only if status is 'error'.

If the timeout exceeded an error will be thrown.