Resolv::Hosts::Dynamic

Dynamic in-memory 'hosts' file for resolving hostnames. Injects entries into an in-memory 'hosts' file which can later be used for name resolution without having to modify the system hosts file. This is an extension to the standard ruby Resolv library and is useful for over-riding name resolution during testing.

Installation

Add this line to your application's Gemfile:

gem 'resolv-hosts-dynamic'

And then execute:

$ bundle

Or install it yourself as:

$ gem install resolv-hosts-dynamic

Usage

Adding entries to the dynamic host resolver

Entries can be added during class instantiation or at any point afterwards (via the add_address method) if we've still got a handle on the object. An entry consists of a hash with the addr and hostname properties, plus an optional aliases property. Entries added during class instantiation can be in the form of a single entry or an array of entries. add_address only accepts a single entry at a time.

require 'resolv-hosts-dynamic'

res = Resolv::Hosts::Dynamic.new([
  {
    'addr'     => '127.1.2.3',
    'hostname' => 'host.example.com',
  },
  {
    'addr'     => '127.4.5.6',
    'hostname' => 'host2.example.com',
    'aliases'  => 'host2',
  },
])

res.add_address({
  'addr'     => '127.7.8.9',
  'hostname' => 'host3.example.com',
  'aliases'  => [ 'host3', 'www.example.com' ],
})

Resolving hostnames/IPs

This class can be used on its own or within the standard ruby Resolv library.

On its own:

require 'resolv-hosts-dynamic'

res = Resolv::Hosts::Dynamic.new({
  'addr'     => '127.1.2.3',
  'hostname' => 'host.example.com',
})

res.getaddress('host.example.com')
res.getname('127.1.2.3')

Within the standard ruby Resolv library:

require 'resolv-hosts-dynamic'

res = Resolv.new([
  Resolv::Hosts::Dynamic.new({
    'addr'     => '127.1.2.3',
    'hostname' => 'host.example.com',
  }),
  Resolv::Hosts.new,
  Resolv::DNS.new,
])

res.getaddress('host.example.com')
res.getname('127.1.2.3')

res.getaddresses('rubygems.org')

Replacing the default resolver in the standard ruby Resolv library (using resolve-replace):

require 'resolv-hosts-dynamic'
require 'resolv-replace'

dynres = Resolv::Hosts::Dynamic.new({
  'addr'     => '127.1.2.3',
  'hostname' => 'host.example.com',
})

Resolv::DefaultResolver.replace_resolvers([
  dynres,
  Resolv::Hosts.new,
  Resolv::DNS.new,
])

Resolv.getaddress('host.example.com')
Resolv.getname('127.1.2.3')
Resolv.getaddresses('www.google.com')

dynres.add_address({
  'addr'     => '127.4.5.6',
  'hostname' => 'www.google.com',
})

Resolv.getaddresses('www.google.com')

Contributing

1. Fork it ( https://github.com/chris-reeves/gem-resolv-hosts-dynamic/fork )
2. Install pre-commit (pip install pre-commit; pre-commit install)
3. Create your feature branch (git checkout -b my-new-feature)
4. Commit your changes (git commit -am 'Add some feature')
5. Push to the branch (git push origin my-new-feature)
6. Create a new Pull Request