Vagrant Host Manager

vagrant-hostmanager is a Vagrant plugin that manages the hosts file on guest machines (and optionally the host). Its goal is to enable resolution of multi-machine environments deployed with a cloud provider where IP addresses are not known in advance.

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Installation

$ vagrant plugin install vagrant-hostmanager

Usage

To update the hosts file on each active machine, run the following command:

$ vagrant hostmanager

The plugin hooks into the vagrant up and vagrant destroy commands automatically. When a machine enters or exits the running state , all active machines with the same provider will have their hosts file updated accordingly. Set the hostmanager.enabled attribute to true in the Vagrantfile to activate this behavior.

To update the host's hosts file, set the hostmanager.manage_host attribute to true.

To update the guests' hosts file, set the hostmanager.manage_guest attribute to true.

A machine's IP address is defined by either the static IP for a private network configuration or by the SSH host configuration. To disable using the private network IP address, set config.hostmanager.ignore_private_ip to true.

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.

If the hostmanager.include_offline attribute is set to true, boxes that are up or have a private ip configured will be added to the hosts file.

In addition, the hostmanager.aliases configuration attribute can be used to provide aliases for your host names.

Example configuration:

Vagrant.configure("2") do |config|
  config.hostmanager.enabled = true
  config.hostmanager.manage_host = true
  config.hostmanager.manage_guest = true
  config.hostmanager.ignore_private_ip = false
  config.hostmanager.include_offline = true
  config.vm.define 'example-box' do |node|
    node.vm.hostname = 'example-box-hostname'
    node.vm.network :private_network, ip: '192.168.42.42'
    node.hostmanager.aliases = %w(example-box.localdomain example-box-alias)
  end
end

Provisioner

Starting at version 1.5.0, vagrant up runs hostmanager before any provisioning occurs. If you would like hostmanager to run after or during your provisioning stage, you can use hostmanager as a provisioner. This allows you to use the provisioning order to ensure that hostmanager runs when desired. The provisioner will collect hosts from boxes with the same provider as the running box.

Example:

# Disable the default hostmanager behavior
config.hostmanager.enabled = false

# ... possible provisioner config before hostmanager ...

# hostmanager provisioner
config.vm.provision :hostmanager

# ... possible provisioning config after hostmanager ...

Custom IP resolver

You can customize way, how host manager resolves IP address for each machine. This might be handy in case of aws provider, where host name is stored in ssh_info hash of each machine. This causes generation of invalid /etc/hosts file.

Custom IP resolver gives you oportunity to calculate IP address for each machine by yourself, giving You also access to the machine that is updating /etc/hosts. For example:

config.hostmanager.ip_resolver = proc do |vm, resolving_vm|
  if hostname = (vm.ssh_info && vm.ssh_info[:host])
    `host #{hostname}`.split("\n").last[/(\d+\.\d+\.\d+\.\d+)/, 1]
  end
end

Passwordless sudo

To avoid being asked for the password every time the hosts file is updated, enable passwordless sudo for the specific command that hostmanager uses to update the hosts file.

• Add the following snippet to the sudoers file (e.g. /etc/sudoers.d/vagrant_hostmanager):

  Cmnd_Alias VAGRANT_HOSTMANAGER_UPDATE = /bin/cp <home-directory>/.vagrant.d/tmp/hosts.local /etc/hosts
  %<admin-group> ALL=(root) NOPASSWD: VAGRANT_HOSTMANAGER_UPDATE
  

  Replace <home-directory> with your actual home directory (e.g. /home/joe) and <admin-group> with the group that is used by the system for sudo access (usually sudo on Debian/Ubuntu systems and wheel on Fedora/Red Hat systems).

• If necessary, add yourself to the <admin-group>:

  usermod -aG <admin-group> <user-name>
  

  Replace <admin-group> with the group that is used by the system for sudo access (see above) and <user-name> with you user name.

Windows support

Hostmanager will detect Windows guests and hosts and use the appropriate path for the hosts file: %WINDIR%\System32\drivers\etc\hosts

By default on a Windows host, the hosts file is not writable without elevated privileges. If hostmanager detects that it cannot overwrite the file, it will attempt to do so with elevated privileges, causing the UAC prompt to appear.

To avoid the UAC prompt, open %WINDIR%\System32\drivers\etc\ in Explorer, right-click the hosts file, go to Properties > Security > Edit and give your user Modify permission.

UAC limitations

Due to limitations caused by UAC, cancelling out of the UAC prompt will not cause any visible errors, however the hosts file will not be updated.

Compatibility

This Vagrant plugin has been tested with the following host and guest operating system combinations.

Date Tested	Vagrant Version	vagrant-hostmanager Version	Host (Workstation) Operating System	Guest (VirtualBox) Operating System
03/23/2016	1.8.1	1.8.1	Ubuntu 14.04 LTS	CentOS 7.2
03/22/2016	1.8.1	1.8.1	OS X 10.11.4	CentOS 7.2
05/03/2017	1.9.4	1.8.6	macOS 10.12.4	Windows Server 2012 R2

Troubleshooting

• Version 1.1 of the plugin prematurely introduced a feature to hook into commands other than vagrant up and vagrant destroy. Version 1.1 broke support for some providers. Version 1.2 reverts this feature until a suitable implementation supporting all providers is available.

• Potentially breaking change in v1.5.0: the running order on vagrant up has changed so that hostmanager runs before provisioning takes place. This ensures all hostnames are available to the guest when it is being provisioned (see #73). Previously, hostmanager would run as the very last action. If you depend on the old behavior, see the provisioner section.

Contribute

To contribute, fork then clone the repository, and then the following:

Developing

1. Install RVM
2. If using MacOS, follow these OpenSSL instructions
3. Use Ruby v3.0.0 rvm use 3.0.0
4. Run bundle install

Testing

1. Build and package your newly developed code:
   • rake gem:build
2. Then install the packaged plugin:
   • vagrant plugin install pkg/vagrant-hostmanager-*.gem
3. Once you're done testing, roll-back to the latest released version:
   • vagrant plugin uninstall vagrant-hostmanager
   • vagrant plugin install vagrant-hostmanager
4. Once you're satisfied developing and testing your new code, please submit a pull request for review.

Releasing

To release a new version of vagrant-hostmanager you will need to do the following:

(only contributors of the GitHub repo and owners of the project at RubyGems will have rights to do this)

1. First, bump, commit, and push the version in ~/lib/vagrant-hostmanager/version.rb:
   • Follow Semantic Versioning.
2. Then, create a matching GitHub Release (this will also create a tag):
   • Preface the version number with a v.
   • https://github.com/devopsgroup-io/vagrant-hostmanager/releases
3. You will then need to build and push the new gem to RubyGems:
   • rake gem:build
   • gem push pkg/vagrant-hostmanager-1.6.1.gem
4. Then, when John Doe runs the following, they will receive the updated vagrant-hostmanager plugin:
   • vagrant plugin update
   • vagrant plugin update vagrant-hostmanager