Now that you’ve gotten a sense of how ansible works, we are going to write our first ansible playbook. The playbook is where you can take some of those ad-hoc commands you just ran and put them into a repeatable set of plays and tasks.

A playbook can have multiple plays and a play can have one or multiple tasks. The goal of a play is to map a group of hosts. The goal of a task is to implement modules against those hosts.

For our first playbook, we are only going to write one play and two tasks.

Section 1 - Creating a Directory Structure and Files for your Playbook

There is a best practice on the preferred directory structures for playbooks. We strongly encourage you to read and understand these practices as you develop your Ansible ninja skills. That said, our playbook today is very basic and creating a complex structure will just confuse things.

Instead, we are going to create a very simple directory structure for our playbook, and add just a couple of files to it.

Step 1: Create a directory called apache_basic in your home directory and change directories into it

 mkdir ~/apache_basic
 cd ~/apache_basic

Step 2: Define your inventory. Inventories are crucial to Ansible as they define remote machines on which you wish to run your playbook(s). Use vi or vim to create a file called hosts. Then, add the appropriate definitions which can be viewed in ~/lightbulb/lessons/lab_inventory/{{studentX}}-instances.txt. (And yes, I suppose you could copy the file, but we’d rather you type it in so you can become familiar with the syntax)

[web]
node-1 ansible_host=<IP Address of your node-1>
node-2 ansible_host=<IP Address of your node-2>

Step 3: Use vi or vim to create a file called install_apache.yml

Section 2 - Defining Your Play

Now that you are editing install_apache.yml, let’s begin by defining the play and then understanding what each line accomplishes

---
- hosts: web
  name: Install the apache web service
  become: yes
  • --- Defines the beginning of YAML

  • hosts: web Defines the host group in your inventory on which this play will run against

  • name: Install the apache web service This describes our play

  • become: yes Enables user privilege escalation. The default is sudo, but su, pbrun, and several others are also supported.

Section 3: Adding Tasks to Your Play

Now that we’ve defined your play, let’s add some tasks to get some things done. Align (vertically) the t in task with the b become.
Yes, it does actually matter. In fact, you should make sure all of your playbook statements are aligned in the way shown here.
If you want to see the entire playbook for reference, skip to the bottom of this exercise.

tasks:
 - name: install apache
   yum:
     name: httpd
     state: present

 - name: start httpd
   service:
     name: httpd
     state: started
  • tasks: This denotes that one or more tasks are about to be defined

  • - name: Each task requires a name which will print to standard output when you run your playbook. Therefore, give your tasks a name that is short, sweet, and to the point


yum:
  name: httpd
  state: present
  • These three lines are calling the Ansible module yum to install httpd. Click here to see all options for the yum module.


service:
  name: httpd
  state: started
  • The next few lines are using the ansible module service to start the httpd service. The service module is the preferred way of controlling services on remote hosts. Click here to learn more about the service module.


Section 4: Review

Now that you’ve completed writing your playbook, it would be a shame not to keep it.

Use the write/quit method in vi or vim to save your playbook, i.e. Esc :wq!

And that should do it. You should now have a fully written playbook called install_apache.yml. You are ready to automate!

Ansible (well, YAML really) can be a bit particular about formatting especially around indentation/spacing. When you all get back to the office, read up on this YAML Syntax a bit more and it will save you some headaches later. In the meantime, your completed playbook should look like this. Take note of the spacing and alignment.
codespace 1
Figure 1: Completed Playbook - w/Spacing