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      How To Use Variables in Ansible Playbooks

      Part of the Series:
      How To Write Ansible Playbooks

      Ansible is a modern configuration management tool that doesn’t require the use of an agent software on remote nodes, using only SSH and Python to communicate and execute commands on managed servers. This series will walk you through the main Ansible features that you can use to write playbooks for server automation. At the end, we’ll see a practical example of how to create a playbook to automate setting up a remote Nginx web server and deploy a static HTML website to it.

      Ansible supports the use of variables to better customize the execution of tasks and playbooks. This way, it’s possible to use the same playbook with different targets and environments.

      Variables can come from different sources, such as the playbook file itself or external variable files that are imported in the playbook. Special precedence rules will apply when working with multiple variable sources that define a variable with the same name.

      To see how variables work in practice, we’ll create a new test playbook that will print the value of two variables, username and home_dir. Create a new file called playbook-02.yml in your ansible-practice directory:

      • nano ~/ansible-practice/playbook-02.yml

      Then add the following lines to the new playbook file:


      - hosts: all
          - username: sammy
          - home: /home/sammy   
          - name: print variables
              msg: "Username: {{ username }}, Home dir: {{ home }}"

      Save and close the file when you’re done editing.

      The vars section of the playbook defines a list of variables that will be injected in the scope of that play. All tasks, as well as any file or template that might be included in the playbook, will have access to these variables.

      To try this playbook on servers from your inventory file, run ansible-playbook with the same connection arguments you’ve used before when running our first example. Again, we’ll be using an inventory file named inventory and the sammy user to connect to the remote servers:

      • ansible-playbook -i inventory playbook-02.yml -u sammy

      You’ll see output like this:


      PLAY [all] *********************************************************************************************************************************************************************************** TASK [Gathering Facts] *********************************************************************************************************************************************************************** ok: [] TASK [print variables] *********************************************************************************************************************************************************************** ok: [] => { "msg": "Username: sammy, Home dir: /home/sammy" } PLAY RECAP *********************************************************************************************************************************************************************************** : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0

      The print variables task will use the debug module to print the values of the two variables we defined in the vars section of the playbook.

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