Using the Linode Ansible Module to Deploy Linodes

Ansible is a popular open-source tool that can be used to automate common IT tasks, like cloud provisioning and configuration management. With Ansible’s 2.8 release, you can deploy Linode instances using our latest API (v4). Ansible’s linode_v4 module adds the functionality needed to deploy and manage Linodes via the command line or in your Ansible Playbooks. While the dynamic inventory plugin for Linode helps you source your Ansible inventory directly from the Linode API (v4).

In this guide you will learn how to:

• Deploy and manage Linodes using Ansible and the linode_v4 module.
• Create an Ansible inventory for your Linode infrastructure using the dynamic inventory plugin for Linode.

Before You Begin

• Add a limited user to your Linode following the steps below, created by following the Add a limited User Account section of our Setting Up and Securing a Compute Instance guide. Ensure that all commands are entered as your limited user.

• Install Ansible on your computer. Use the steps in the Control Node Setup section of the Getting Started With Ansible - Basic Installation and Setup guide.

• Ensure you have Python version 2.7 or higher installed on your computer. Issue the following command to check your system’s Python version:

  python --version
  

• Install the official Python library for the Linode API v4.

  sudo apt-get install python-pip
  sudo pip install linode_api4
  

• Generate a Linode API v4 access token with permission to read and write Linodes. You can follow the Get an Access Token section of the Getting Started with the Linode API guide if you do not already have one.

• Create an authentication Key-pair if your computer does not already have one.

Configure Ansible

The Ansible configuration file is used to adjust Ansible’s default system settings. Ansible will search for a configuration file in the directories listed below, in the order specified, and apply the first configuration values it finds:

• ANSIBLE_CONFIG environment variable pointing to a configuration file location. If passed, it will override the default Ansible configuration file.
• ansible.cfg file in the current directory
• ~/.ansible.cfg in the home directory
• /etc/ansible/ansible.cfg

In this section, you will create an Ansible configuration file and add options to disable host key checking, and to allow the Linode inventory plugin. The Ansible configuration file will be located in a development directory that you create, however, it could exist in any of the locations listed above. See Ansible’s official documentation for a full list of available configuration settings.

1. In your home directory, create a directory to hold all of your Ansible related files and move into the directory:

   mkdir development && cd development
   

2. Create the Ansible configuration file, ansible.cfg in the development directory and add the host_key_checking and enable_plugins options.

   File: ~/development/ansible.cfg

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   [defaults] host_key_checking = False VAULT_PASSWORD_FILE = ./vault-pass [inventory] enable_plugins = linode

   • host_key_checking = False will allow Ansible to SSH into hosts without having to accept the remote server’s host key. This will disable host key checking globally.
   • VAULT_PASSWORD_FILE = ./vault-pass is used to specify a Vault password file to use whenever Ansible Vault requires a password. Ansible Vault offers several options for password management. To learn more password management, read Ansible’s Providing Vault Passwords documentation.
   • enable_plugins = linode enables the Linode dynamic inventory plugin.

Create a Linode Instance

You can now begin creating Linode instances using Ansible. In this section, you will create an Ansible Playbook that can deploy Linodes.

Create your Linode Playbook

1. Ensure you are in the development directory that you created in the Configure Ansible section:

   cd ~/development
   

2. U sing your preferred text editor, create the Create Linode Playbook file and include the following values:

   File: ~/development/linode_create.yml

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   - name: Create Linode hosts: localhost vars_files: - ./group_vars/example_group/vars tasks: - name: Create a new Linode. linode_v4: label: "{{ label }}{{ 100 |random }}" access_token: "{{ token }}" type: g6-nanode-1 region: us-east image: linode/debian9 root_pass: "{{ password }}" authorized_keys: "{{ ssh_keys }}" group: example_group tags: example_group state: present register: my_linode

   • The Playbook my_linode contains the Create Linode play, which will be executed on hosts: localhost. This means the Ansible playbook will execute on the local system and use it as a vehicle to deploy the remote Linode instances.

   • The vars_files key provides the location of a local file that contains variable values to populate in the play. The value of any variables defined in the vars file will substitute any Jinja template variables used in the Playbook. Jinja template variables are any variables between curly brackets, like: {{ my_var }}.

   • The Create a new Linode task calls the linode_v4 module and provides all required module parameters as arguments, plus additional arguments to configure the Linode’s deployment. For details on each parameter, see the linode_v4 Module Parameters section.

     Note

     Usage of groups is deprecated, but still supported by Linode’s API v4. The Linode dynamic inventory module requires groups to generate an Ansible inventory and will be used later in this guide.

   • Theregister keyword defines a variable name, my_linode that will store linode_v4 module return data. For instance, you could reference the my_linode variable later in your Playbook to complete other actions using data about your Linode. This keyword is not required to deploy a Linode instance, but represents a common way to declare and use variables in Ansible Playbooks. The task in the snippet below will use Ansible’s debug module and the my_linode variable to print out a message with the Linode instance’s ID and IPv4 address during Playbook execution.

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     ... - name: Print info about my Linode instance debug: msg: "ID is {{ my_linode.instance.id }} IP is {{ my_linode.instance.ipv4 }}"

Create the Variables File

In the previous section, you created the Create Linode Playbook to deploy Linode instances and made use of Jinja template variables. In this section, you will create the variables file to provide values to those template variables.

1. Create the directory to store your Playbook’s variable files. The directory is structured to group your variable files by inventory group. This directory structure supports the use of file level encryption that Ansible Vault can detect and parse. Although it is not relevant to this guide’s example, it will be used as a best practice.

   mkdir -p ~/development/group_vars/example_group/
   

2. Create the variables file and populate it with the example variables. You can replace the values with your own.

   File: ~/development/group_vars/example_group/vars

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   ssh_keys: > ['ssh-rsa AAAAB3N..5bYqyRaQ== user@mycomputer', '~/.ssh/id_rsa.pub'] label: simple-linode-

   • The ssh_keys example passes a list of two public SSH keys. The first provides the string value of the key, while the second provides a local public key file location.

     Configure your SSH Agent

     If your SSH Keys are passphrase-protected, you should add the keys to your SSH agent so that Ansible does not hang when running Playbooks on the remote Linode. For Linux users, run the following command. If you stored your private key in another location, update the path that’s passed to ssh-add accordingly:

     eval $(ssh-agent) && ssh-add ~/.ssh/id_rsa
     

     If you start a new terminal, you will need to run the commands in this step again before having access to the keys stored in your SSH agent.

   • label provides a label prefix that will be concatenated with a random number. This occurs when the Create Linode Playbook’s Jinja templating for the label argument is parsed (label: "{{ label }}{{ 100 |random }}").

Encrypt Sensitive Variables with Ansible Vault

Ansible Vault allows you to encrypt sensitive data, like passwords or tokens, to keep them from being exposed in your Ansible Playbooks or Roles. You will take advantage of this functionality to keep your Linode instance’s password and access_token encrypted within the variables file.

1. Create your Ansible Vault password file and add your password to the file. Remember the location of the password file was configured in the ansible.cfg file in the Configure Ansible section of this guide.

   File: ~/development/vault-pass

   1	My.ANS1BLEvault-c00lPassw0rd

2. Encrypt the value of your Linode’s root user password using Ansible Vault. Replace My.c00lPassw0rd with your own strong password that conforms to the root_pass parameter’s constraints.

   ansible-vault encrypt_string 'My.c00lPassw0rd' --name 'password'
   

   You will see a similar output:

   password: !vault |
       $ANSIBLE_VAULT;1.1;AES256
       30376134633639613832373335313062366536313334316465303462656664333064373933393831
       3432313261613532346134633761316363363535326333360a626431376265373133653535373238
       38323166666665376366663964343830633462623537623065356364343831316439396462343935
       6233646239363434380a383433643763373066633535366137346638613261353064353466303734
       3833</br>
   Encryption successful

3. Copy the generated output and add it to your vars file.

4. Encrypt the value of your access token. Replace the value of 86210...1e1c6bd with your own access token.

   ansible-vault encrypt_string '86210...1e1c6bd' --name 'token'
   

5. Copy the generated output and append it to the bottom of your vars file.

   The final vars file should resemble the example below:

   File: ~/development/group_vars/example_group/vars

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   ssh_keys: > ['ssh-rsa AAAAB3N..5bYqyRaQ== user@mycomputer', '~/.ssh/id_rsa.pub'] label: simple-linode- password: !vault | $ANSIBLE_VAULT;1.1;AES256 30376134633639613832373335313062366536313334316465303462656664333064373933393831 3432313261613532346134633761316363363535326333360a626431376265373133653535373238 38323166666665376366663964343830633462623537623065356364343831316439396462343935 6233646239363434380a383433643763373066633535366137346638613261353064353466303734 3833 token: !vault | $ANSIBLE_VAULT;1.1;AES256 65363565316233613963653465613661316134333164623962643834383632646439306566623061 3938393939373039373135663239633162336530373738300a316661373731623538306164363434 31656434356431353734666633656534343237333662613036653137396235353833313430626534 3330323437653835660a303865636365303532373864613632323930343265343665393432326231 61313635653463333630636631336539643430326662373137303166303739616262643338373834 34613532353031333731336339396233623533326130376431346462633832353432316163373833 35316333626530643736636332323161353139306533633961376432623161626132353933373661 36663135323664663130

Run the Ansible Playbook

You are now ready to run the Create Linode Playbook. When you run the Playbook, a 1GB Linode (Nanode) will be deployed in the Newark data center. Note: you want to run Ansible commands from the directory where your ansible.cfg file is located.

1. Run your playbook to create your Linode instances.

   ansible-playbook ~/development/linode_create.yml
   

   You will see a similar output:

   PLAY [Create Linode] *********************************************************************
   
   TASK [Gathering Facts] *******************************************************************
   ok: [localhost]
   
   TASK [Create a new Linode.] **************************************************************
   changed: [localhost]
   
   PLAY RECAP *******************************************************************************
   localhost                  : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

linode_v4 Module Parameters

The Linode Dynamic Inventory Plugin

Ansible uses inventories to manage different hosts that make up your infrastructure. This allows you to execute tasks on specific parts of your infrastructure. By default, Ansible will look in /etc/ansible/hosts for an inventory, however, you can designate a different location for your inventory file and use multiple inventory files that represent your infrastructure. To support infrastructures that shift over time, Ansible offers the ability to track inventory from dynamic sources, like cloud providers. The Ansible dynamic inventory plugin for Linode can be used to source your inventory from Linode’s API v4. In this section, you will use the Linode plugin to source your Ansible deployed Linode inventory.

Configure the Plugin

1. Configure the Ansible dynamic inventory plugin for Linode by creating a file named linode.yml.

   File: ~/development/linode.yml

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   plugin: linode regions: - us-east groups: - example_group types: - g6-nanode-1

   • The configuration file will create an inventory for any Linodes on your account that are in the us-east region, part of the example_group group and of type g6-nanode-1. Any Linodes that are not part of the example_group group, but that fulfill the us-east region and g6-nanode-type type will be displayed as ungrouped. All other Linodes will be excluded from the dynamic inventory. For more information on all supported parameters, see the Plugin Parameters section.

Run the Inventory Plugin

1. Export your Linode API v4 access token to the shell environment. LINODE_ACCESS_TOKEN must be used as the environment variable name. Replace mytoken with your own access token.

   export LINODE_ACCESS_TOKEN='mytoken'
   

2. Run the Linode dynamic inventory plugin.

   ansible-inventory -i ~/development/linode.yml --graph
   

   You should see a similar output. The output may vary depending on the Linodes already deployed to your account and the parameter values you pass.

   @all:
   |--@example_group:
   |  |--simple-linode-29
   

   For a more detailed output including all Linode instance configurations, issue the following command:

   ansible-inventory -i ~/development/linode.yml --graph --vars
   

3. Before you can communicate with your Linode instances using the dynamic inventory plugin, you will need to add your Linode’s IPv4 address and label to your /etc/hosts file.

   The Linode Dynamic Inventory Plugin assumes that the Linodes in your account have labels that correspond to hostnames that are in your resolver search path, /etc/hosts. This means you will have to create an entry in your /etc/hosts file to map the Linode’s IPv4 address to its hostname.

   Note

   A pull request currently exists to support using a public IP, private IP or hostname. This change will enable the inventory plugin to be used with infrastructure that does not have DNS hostnames or hostnames that match Linode labels.

   To add your deployed Linode instance to the /etc/hosts file:

   • Retrieve your Linode instance’s IPv4 address:

     ansible-inventory -i ~/development/linode.yml --graph --vars | grep 'ipv4\|simple-linode'
     

     Your output will resemble the following:

     |  |--simple-linode-36
     |  |  |--{ipv4 = [u'192.0.2.0']}
     |  |  |--{label = simple-linode-36}

   • Open the /etc/hosts file and add your Linode’s IPv4 address and label:

     File: /etc/hosts

     1 2	127.0.0.1 localhost 192.0.2.0 simple-linode-29

4. Verify that you can communicate with your grouped inventory by pinging the Linodes. The ping command will use the dynamic inventory plugin configuration file to target example_group. The u root option will run the command as root on the Linode hosts.

   ansible -m ping example_group -i ~/development/linode.yml -u root
   

   You should see a similar output:

   simple-linode-29 | SUCCESS => {
       "ansible_facts": {
           "discovered_interpreter_python": "/usr/bin/python"
       },
       "changed": false,
       "ping": "pong"
   }

Plugin Parameters

Delete Your Resources

1. To delete the Linode instance created in this guide, create a Delete Linode Playbook with the following content in the example. Replace the value of label with your Linode’s label:

   File: ~/development/linode_delete.yml

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   - name: Delete Linode hosts: localhost vars_files: - ./group_vars/example_group/vars tasks: - name: Delete your Linode Instance. linode_v4: label: simple-linode-29 state: absent

2. Run the Delete Linode Playbook:

   ansible-playbook ~/development/linode_delete.yml
   

More Information

You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

• Ansible Best Practices