Proof-of-concept support for managing /etc/hosts.

Hooks into the up and destroy commands to manage changes to
the /etc/hosts file on active machines.

.gitignore

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+*.gem
+pkg
+Gemfile.lock
+test/.vagrant

Gemfile

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+source 'https://rubygems.org'
+
+gemspec
+
+group :development do
+  gem 'vagrant', github: 'mitchellh/vagrant', tag: 'v1.1.2'
+end

LICENSE.txt

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+Copyright (c) 2013 Shawn Dahlen
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+Vagrant Host Manager
+====================
+`vagrant-hostmanager` is a Vagrant 1.1+ plugin that manages the `/etc/hosts`
+file on guest machines. Its goal is to enable resolution of multi-machine
+environments deployed with a cloud provider where IP addresses are not known
+in advance.
+
+Status
+------
+The current implementation is a proof-of-concept supporting the larger
+objective of using Vagrant as a cloud management interface for development
+and production environments.
+
+The plugin has been tested with Vagrant 1.1.4.
+
+Installation
+------------
+Install the plugin following the typical Vagrant 1.1 procedure:
+
+    vagrant plugin install vagrant-hostmanager
+
+Usage
+-----
+The plugin hooks into the `vagrant up` and `vagrant destroy` commands
+automatically updating the `/etc/hosts` file on each active machine that
+is using the same provider.
+
+A machine's IP address is defined by either the static IP for a private
+network configuration or by the SSH host configuration.
+
+A machine's host name is defined by `config.vm.hostname`. If this is not
+set, it falls back to the symbol defining the machine in the Vagrantfile.
+
+Contribute
+----------
+Contributions are welcome.
+
+1. Fork it
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Add some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create new Pull Request

bin/build.sh

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+rm *.gem
+gem uninstall -a vagrant-hostmanager
+gem build *.gemspec
+gem install *.gem
+vagrant plugin install vagrant-hostmanager

bin/test.sh

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+cd test
+vagrant up
+echo "[server1] /etc/hosts file:"
+vagrant ssh server1 -c 'cat /etc/hosts'
+echo "[server2] /etc/hosts file:"
+vagrant ssh server2 -c 'cat /etc/hosts'
+vagrant destroy server1 -f
+echo "[server2] /etc/hosts file:"
+vagrant ssh server2 -c 'cat /etc/hosts'
+vagrant destroy server2 -f
+cd ..
+

lib/vagrant-hostmanager.rb

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+require 'vagrant'
+require 'vagrant-hostmanager/plugin'
+require 'vagrant-hostmanager/version'
+require 'vagrant-hostmanager/errors'
+
+module VagrantPlugins
+  module HostManager
+    def self.source_root
+      @source_root ||= Pathname.new(File.expand_path('../../', __FILE__))
+    end
+  end
+end

lib/vagrant-hostmanager/action/update_hosts_file.rb

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+module VagrantPlugins
+  module HostManager
+    module Action
+      class UpdateHostsFile
+        def initialize(app, env)
+          @app, @env = app, env
+          @translator = Helpers::Translator.new('action.update_hosts_file')
+          @logger = 
+            Log4r::Logger.new('vagrant_hostmanager::action::update')
+        end
+
+        def call(env)
+          global_env = env[:machine].env
+          current_provider = env[:machine].provider_name
+
+          # build a list of host entries based on active machines that
+          # are using the same provider as the current one
+          matching_machines = []
+          entries = {}
+          entries['127.0.0.1'] = 'localhost'
+          global_env.active_machines.each do |name, provider|
+            if provider == current_provider
+              machine = global_env.machine(name, provider)
+              host = machine.config.vm.hostname || name
+              entries[get_ip_address(machine)] = host
+              matching_machines << machine
+            end
+          end
+
+          # generate hosts file
+          path = env[:tmp_path].join('hosts')
+          File.open(path, 'w') do |file|
+            entries.each_pair do |ip, host|
+              @logger.info "Adding /etc/hosts entry: #{ip} #{host}"
+              file << "#{ip}\t#{host}\n"
+            end
+          end
+
+          # copy the hosts file to each matching machine
+          # TODO append hostname to loopback address
+          matching_machines.each do |machine|
+            env[:ui].info @translator.t('update', { :name => machine.name })
+            machine.communicate.upload(path, '/tmp/hosts')
+            machine.communicate.sudo("mv /tmp/hosts /etc/hosts")
+          end
+
+          @app.call(env)
+        end
+
+        protected
+
+        def get_ip_address(machine)
+          ip = nil
+          machine.config.vm.networks.each do |network|
+            key, options = network[0], network[1]
+            ip = options[:ip] if key == :private_network
+            next if ip
+          end
+
+          ip || machine.ssh_info[:host]
+        end
+      end
+    end
+  end
+end

lib/vagrant-hostmanager/errors.rb

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+module VagrantPlugins
+  module HostManager
+    module Errors
+    end
+  end
+end

lib/vagrant-hostmanager/helpers/translator.rb

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+module VagrantPlugins
+  module HostManager
+    module Helpers
+      class Translator
+        def self.plugin_namespace=(val)
+          @@plugin_namespace = val
+        end
+
+        def initialize(namespace)
+          @namespace = namespace
+        end
+
+        def t(keys, opts = {})
+          value = I18n.t("#{@@plugin_namespace}.#{@namespace}.#{keys}", opts)
+          opts[:progress] == false ? value : value + "..."
+        end
+      end
+    end
+  end
+end

lib/vagrant-hostmanager/plugin.rb

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+require 'vagrant-hostmanager/helpers/translator'
+require 'vagrant-hostmanager/action/update_hosts_file'
+
+module VagrantPlugins
+  module HostManager
+    class Plugin < Vagrant.plugin('2')
+      name 'HostManager'
+      description <<-DESC
+        This plugin manages the /etc/hosts file for guest machines. A entry is
+        created for each active machine using the hostname attribute.
+      DESC
+
+      action_hook(:hostmanager_up, :machine_action_up) do |hook|
+        setup_i18n
+        setup_logging
+
+        # TODO use hook.append when defect is fixed within vagrant
+        hook.after(ProviderVirtualBox::Action::Boot, Action::UpdateHostsFile)
+      end
+
+      action_hook(:hostmanger_destroy, :machine_action_destroy) do |hook|
+        setup_i18n
+        setup_logging
+
+        # TODO use hook.append when defect is fixed within vagrant
+        hook.after(
+          ProviderVirtualBox::Action::DestroyUnusedNetworkInterfaces,
+          Action::UpdateHostsFile)
+      end
+
+      def self.setup_i18n
+        I18n.load_path << File.expand_path('locales/en.yml', HostManager.source_root)
+        I18n.reload!
+        Helpers::Translator.plugin_namespace = 'vagrant_hostmanager'
+      end
+
+      def self.setup_logging
+        level = nil
+        begin
+          level = Log4r.const_get(ENV["VAGRANT_LOG"].upcase)
+        rescue NameError
+          # This means that the logging constant wasn't found,
+          # which is fine. We just keep `level` as `nil`. But
+          # we tell the user.
+          level = nil
+        end
+
+        # Some constants, such as "true" resolve to booleans, so the
+        # above error checking doesn't catch it. This will check to make
+        # sure that the log level is an integer, as Log4r requires.
+        level = nil if !level.is_a?(Integer)
+
+        # Set the logging level on all "vagrant" namespaced
+        # logs as long as we have a valid level.
+        if level
+          logger = Log4r::Logger.new("vagrant_hostmanager")
+          logger.outputters = Log4r::Outputter.stderr
+          logger.level = level
+          logger = nil
+        end
+      end
+    end
+  end
+end

lib/vagrant-hostmanager/version.rb

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+module VagrantPlugins
+  module HostManager
+    VERSION = '0.0.1'
+  end
+end

locales/en.yml

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+en:
+  vagrant_hostmanager:
+    action:
+      update_hosts_file:
+        update: "Updating /etc/hosts file on %{name}"

test/Vagrantfile

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+# -*- mode: ruby -*-
+# vi: set ft=ruby :
+
+Vagrant.configure('2') do |config|
+  config.vm.box = 'precise64-chef11.2'
+  config.vm.box_url = 'https://opscode-vm.s3.amazonaws.com/vagrant/opscode_ubuntu-12.04_chef-11.2.0.box'
+
+  config.vm.define :server1 do |server|
+    server.vm.hostname = 'fry'
+    server.vm.network :private_network, :ip => '10.0.5.2'
+  end
+
+  config.vm.define :server2 do |server|
+    server.vm.hostname = 'bender'
+    server.vm.network :private_network, :ip => '10.0.5.3'
+  end
+end

vagrant-hostmanager.gemspec

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+# -*- encoding: utf-8 -*-
+lib = File.expand_path('../lib', __FILE__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+require 'vagrant-hostmanager/version'
+
+Gem::Specification.new do |gem|
+  gem.name          = 'vagrant-hostmanager'
+  gem.version       = VagrantPlugins::HostManager::VERSION
+  gem.authors       = ['Shawn Dahlen']
+  gem.email         = ['shawn@dahlen.me']
+  gem.description   = %q{A Vagrant plugin that manages the /etc/hosts file within a multi-machine environment}
+  gem.summary       = gem.description
+
+  gem.files         = `git ls-files`.split($/)
+  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
+  gem.require_paths = ['lib']
+end