Table of Contents
Playbooks use the YAML format to define one or more *plays*. A play is a set of ordered tasks that are arranged in a way to automate a process, such as setting up a web server or deploying an application to production.
In a playbook file, plays are defined as a YAML list. A typical play starts off by determining which hosts are the target of that particular setup. This is done with the hosts directive.
Setting the hosts directive to all is a common choice because you can limit the targets of a play at execution time by running the ansible-playbook command with the -l parameter. That allows you to run the same playbook on different servers or groups without the need to change the playbook file every time.
Start by creating a new directory on your home folder where you can save your practice playbooks. First, make sure you’re in your Ubuntu user’s home directory. From there, create a directory named ansible-practice and then navigate into that directory with the cd command:
cd ~
mkdir <^>ansible-practice<^>
cd <^>ansible-practice<^>
If you followed all prerequisites, you should already have a working inventory file. You can copy that file into your new ansible-practice directory now. For instance, if you created your test inventory file in an ansible directory in your home folder, you could copy the file to the new directory with:
cp ~/ansible/inventory ~/ansible-practice/inventory
Next, create a new playbook file:
nano <^>playbook-01.yml<^>
The following playbook defines a play targeting all hosts from a given inventory. It contains a single task to print a debug message.
Note: We'll learn more about tasks in the next section of this series.
Add the following content to your playbook-01.yml file:
[label ~/ansible-practice/playbook-01.yml]
---
- hosts: all
tasks:
- name: Print message
debug:
msg: Hello Ansible World
Save and close the file when you're done. If you're using nano, you can do that by typing CTRL+X, then Y and ENTER to confirm.
To try this playbook on the server(s) that you set up in your inventory file, run ansible-playbook with the same connection arguments you used when running a connection test within the introduction of this series. Here, we'll be using an inventory file named inventory and the sammy user to connect to the remote server, but be sure to change these details to align with your own inventory file and administrative user:
ansible-playbook -i inventory <^>playbook-01.yml<^> -u sammy
You'll see output like this:
[secondary_label Output]
PLAY [all] ***********************************************************************************
TASK [Gathering Facts] ***********************************************************************
ok: [203.0.113.10]
TASK [Update apt cache] **********************************************************************
ok: [203.0.113.10] => {
"msg": "Hello Ansible World"
}
PLAY RECAP ***********************************************************************************
203.0.113.10 : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
You might have noticed that even though you have defined only one task within your playbook, two tasks were listed in the play output. At the beginning of each play, Ansible executes by default an additional task that gathers information — referred to as *facts* — about the remote nodes. Because facts can be used on playbooks to better customize the behavior of tasks, the fact-gathering task must happen before any other tasks are executed.
We'll learn more about Ansible facts in a later section of this series.
