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Ansible - Provisioning	provisioning-ansible

Ansible Provisioner

Provisioner name: "ansible"

The ansible provisioner allows you to provision the guest using Ansible playbooks.

Ansible playbooks are YAML documents that comprise the set of steps to be orchestrated on one or more machines. This documentation page will not go into how to use Ansible or how to write Ansible playbooks, since Ansible is a complete deployment and configuration management system that is beyond the scope of a single page of documentation.

Warning: If you're not familiar with Ansible and Vagrant already, I recommend starting with the shell provisioner. However, if you're comfortable with Vagrant already, Vagrant is a great way to learn Ansible.

Inventory File

When using Ansible, it needs to know on which machines a given playbook should run. It does this by way of an inventory file which lists those machines. In the context of Vagrant, there are two ways to approach working with inventory files.

The first and simplest option is to not provide one to Vagrant at all. Vagrant will generate an inventory file encompassing all of the virtual machines it manages, and use it for provisioning machines. The generated inventory file is stored as part of your local Vagrant environment in .vagrant/provisioners/ansible/inventory/vagrant_ansible_inventory.

The ansible.groups option can be used to pass a hash of group names and group members to be included in the generated inventory file. Group variables are intentionally not supported, as this practice is not recommended. For example:

ansible.groups = {
  "group1" => ["machine1"],
  "group2" => ["machine2", "machine3"],
  "all_groups:children" => ["group1", "group2", "group3"]
}

Note that unmanaged machines and undefined groups are not added to the inventory. For example, group3 in the above example would not be added to the inventory file.

A generated inventory might look like:

# Generated by Vagrant

machine1 ansible_ssh_host=127.0.0.1 ansible_ssh_port=2200
machine2 ansible_ssh_host=127.0.0.1 ansible_ssh_port=2201

[group1]
machine1

[group2]
machine2

[all_groups:children]
group1
group2

The second option is for situations where you'd like to have more control over the inventory management. With the ansible.inventory_path option, you can reference a specific inventory resource (e.g. a static inventory file, a dynamic inventory script or even multiple inventories stored in the same directory). Vagrant will then use this inventory information instead of generating it.

A very simple inventory file for use with Vagrant might look like:

default ansible_ssh_host=192.168.111.222

Where the above IP address is one set in your Vagrantfile:

config.vm.network :private_network, ip: "192.168.111.222"

Note that machine names in Vagrantfile and ansible.inventory_path file should correspond, unless you use ansible.limit option to reference the correct machines.

Playbook

The second component of a successful Ansible provisioner setup is the Ansible playbook which contains the steps that should be run on the guest. Ansible's playbook documentation goes into great detail on how to author playbooks, and there are a number of best practices that can be applied to use Ansible's powerful features effectively. A playbook that installs and starts (or restarts if it was updated) the NTP daemon via YUM looks like:

---
- hosts: all
  tasks:
    - name: ensure ntpd is at the latest version
      yum: pkg=ntp state=latest
      notify:
      - restart ntpd
  handlers:
    - name: restart ntpd
      service: name=ntpd state=restarted

You can of course target other operating systems that don't have YUM by changing the playbook tasks. Ansible ships with a number of modules that make running otherwise tedious tasks dead simple.

Running Ansible

To run Ansible against your Vagrant guest, the basic Vagrantfile configuration looks like:

Vagrant.configure("2") do |config|
  config.vm.provision "ansible" do |ansible|
    ansible.playbook = "playbook.yml"
  end
end

Since an Ansible playbook can include many files, you may also collect the related files in a directory structure like this:

$ tree
.
|-- Vagrantfile
|-- provisioning
|   |-- group_vars
|           |-- all
|   |-- playbook.yml

In such an arrangement, the ansible.playbook path should be adjusted accordingly:

Vagrant.configure("2") do |config|
  config.vm.provision "ansible" do |ansible|
    ansible.playbook = "provisioning/playbook.yml"
  end
end

Vagrant will try to run the playbook.yml playbook against all machines defined in your Vagrantfile.

Backward Compatibility Note:

Up to Vagrant 1.4, the Ansible provisioner could potentially connect (multiple times) to all hosts from the inventory file. This behaviour is still possible by setting ansible.limit = 'all' (see more details below).

Additional Options

The Ansible provisioner also includes a number of additional options that can be set, all of which get passed to the ansible-playbook command that ships with Ansible.

• ansible.extra_vars can be used to pass additional variables (with highest priority) to the playbook. This parameter can be a path to a JSON or YAML file, or a hash. For example:

  ansible.extra_vars = {
    ntp_server: "pool.ntp.org",
    nginx: {
      port: 8008,
      workers: 4
    }
  }
  

  These variables take the highest precedence over any other variables.

• ansible.sudo can be set to true to cause Ansible to perform commands using sudo.

• ansible.sudo_user can be set to a string containing a username on the guest who should be used by the sudo command.

• ansible.ask_sudo_pass can be set to true to require Ansible to prompt for a sudo password.

• ansible.ask_vault_pass can be set to true to require Ansible to prompt for a vault password.

• ansible.vault_password_file can be set to a string containing the path of a file containing the password used by Ansible Vault.

• ansible.limit can be set to a string or an array of machines or groups from the inventory file to further control which hosts are affected. Note that:

  • As of Vagrant 1.5, the machine name (taken from Vagrantfile) is set as default limit to ensure that vagrant provision steps only affect the expected machine. Setting ansible.limit will override this default.
  • Setting ansible.limit = 'all' can be used to make Ansible connect to all machines from the inventory file.

• ansible.verbose can be set to increase Ansible's verbosity to obtain detailed logging:

  • 'v', verbose mode
  • 'vv'
  • 'vvv', more
  • 'vvvv', connection debugging

• ansible.tags can be set to a string or an array of tags. Only plays, roles and tasks tagged with these values will be executed.

• ansible.skip_tags can be set to a string or an array of tags. Only plays, roles and tasks that do not match these values will be executed.

• ansible.start_at_task can be set to a string corresponding to the task name where the playbook provision will start.

• ansible.raw_arguments can be set to an array of strings corresponding to a list of ansible-playbook arguments (e.g. ['--check', '-M /my/modules']). It is an unsafe wildcard that can be used to apply Ansible options that are not (yet) supported by this Vagrant provisioner. Following precedence rules apply:

  • Any supported options (described above) will override conflicting raw_arguments value (e.g. --tags or --start-at-task)
  • Vagrant default user authentication can be overridden via raw_arguments (with custom values for --user and --private-key)

• ansible.raw_ssh_args can be set to an array of strings corresponding to a list of OpenSSH client parameters (e.g. ['-o ControlMaster=no']). It is an unsafe wildcard that can be used to pass additional SSH settings to Ansible via ANSIBLE_SSH_ARGS environment variable.

• ansible.host_key_checking can be set to true which will enable host key checking. As Vagrant 1.5, the default value is false, to avoid connection problems when creating new virtual machines.

Tips and Tricks

Ansible Parallel Execution

Vagrant is designed to provision multi-machine environments in sequence, but the following configuration pattern can be used to take advantage of Ansible parallelism:

  config.vm.define 'machine2' do |machine|
    machine.vm.hostname = 'machine2'
    machine.vm.network "private_network", ip: "192.168.77.22"
  end

  config.vm.define 'machine1' do |machine|
    machine.vm.hostname = 'machine1'
    machine.vm.network "private_network", ip: "192.168.77.21"

    machine.vm.provision :ansible do |ansible|
      ansible.playbook = "playbook.yml"

      # Disable default limit (required with Vagrant 1.5+)
      ansible.limit = 'all'
    end
  end

Provide a local ansible.cfg file

Certain settings in Ansible are (only) adjustable via a configuration file, and you might want to ship such a file in your Vagrant project.

As ansible-playbook command looks for local ansible.cfg configuration file in its current directory (but not in the directory that contains the main playbook), you have to store this file adjacent to your Vagrantfile.

Note that it is also possible to reference an Ansible configuration file via ANSIBLE_CONFIG environment variable, if you want to be flexible about the location of this file.

Why does the Ansible provisioner connect as the wrong user?

It is good to know that the following Ansible settings always override the config.ssh.username option defined in Vagrant SSH Settings:

• ansible_ssh_user variable
• remote_user (or user) play attribute
• remote_user task attribute

Be aware that copying snippets from the Ansible documentation might lead to this problem, as root is used as the remote user in many examples.

Example of an SSH error (with vvv log level), where an undefined remote user xyz has replaced vagrant:

TASK: [my_role | do something] *****************
<127.0.0.1> ESTABLISH CONNECTION FOR USER: xyz
<127.0.0.1> EXEC ['ssh', '-tt', '-vvv', '-o', 'ControlMaster=auto',...
fatal: [ansible-devbox] => SSH encountered an unknown error. We recommend you re-run the command using -vvvv, which will enable SSH debugging output to help diagnose the issue.

In a situation like the above, to override the remote_user specified in a play you can use the following line in your Vagrantfile vm.provision block:

ansible.extra_vars = { ansible_ssh_user: 'vagrant' }