rif

Node.js module to resolve network interfaces.

This modules provides a concise way to extract an IP address from the output of require('os').networkInterfaces().

This is useful for deployments where the environment (e.g. Docker, AWS) picks the IP addresses for you.

Note: use the command line utilities ifconfig or ipconfig to list actual interface names on your system.

Example

var rif = require('rif')()

console.log(rif('lo')) // prints IPv4 address of loopback interface: 127.0.0.1
console.log(rif('lo/6')) // prints IPv6 address of loopback interface: ::1
console.log(rif('eth0')) // prints IPv4 address of interface eth0: 10.x.x.x (depends on your system!)

console.log(rif('lo/4/netmask=255.0.0.0')) // netmask field must equal 255.0.0.0
console.log(rif('lo/4/netmask^255,internal=true')) // netmask field must start with 255 and internal field must have value true

console.log(rif('//address^192.168')) // prints first found address of any interface of any family,
                                      // where address starts with 192.168

You can optionally provide a fixed set of pre-defined interfaces. This useful for testing (see (seneca-mesh/test/mesh.test.js)[github.com/rjrodger/seneca-mesh/blob/master/test/mesh.test.js]).

var rif = require('rif')({
  my_interface: [{
    address: '192.168.1.2'
  }]
})

console.log(rif('lo')) // prints IPv4 address of loopback interface: 127.0.0.1
console.log(rif('my_interface')) // prints 192.168.1.2

Syntax

ifname/v/fieldspec

• ifname: name of network interface.
  • values: * (or empty string): match any; string: match exact interface name
• v: (optional) IP version: 4 or 6, meaning IPv4 or IPv6 respectively.
  • values: 4: IPv4; 6: IPv6; * (or empty string): match either IP family
• fieldspec: (optional) comma-separated list of field value tests

The field value tests are of the form: name#value where # is one of:

• =: exact match.
• ^: field starts with value.
• $: field ends with value.
• %: field contains value.

See unit tests for more examples.

License

Copyright (c) 2016, Richard Rodger and other contributors, MIT License.