Creating Ansible Roles
======================

Published  : 20 January 2025
Reading    : 5 min
Tags       : Ansible
URL        : https://ctrl-find.nl/posts/ansible_roles/
Plain text : https://ctrl-find.nl/posts/ansible_roles/index.txt

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### Why Roles over Playbooks? 
Single playbooks are great for tasks but when a project starts getting complexer, it way more managable in a role then a single playbook.
Ansible role is a predefined set of playbooks that is build for a specific purpose.
All the necessary configurations can be set and build into the role.

### Creating the role
We create the role in the folder we've been using in the previous parts `/Users/sebas/Desktop/ansible`.
With following command we can create a pre-setup role through ansible.

```bash
ansible-galaxy init /Users/sebas/Desktop/ansible/<name role> 
```

#### Role layout
This is the layout of the pre-setup role we've created through the previous command.

```bash
machine_info                   # Name of the role (created through the init command)
├── README.md                  # Default setup for a readme of the role
├── defaults                   # Standard config place, which can be used in tasks
│   └── main.yml               
├── files                      # Place here all necessary files needed for your role
├── handlers                   # Default place for adding task handlers
│   └── main.yml
├── meta                       # Informational place when you list your role to the internet
│   └── main.yml
├── tasks                      # Tasks folder where playbooks go
│   ├── 00_gather_facts.yml
│   ├── 01_hostname.yml
│   ├── 02_ram.yml
│   └── main.yml
├── templates                   # A place for all templated files which can be used in tasks often defined in jinja templates.
├── tests                       # Created for testing your role
│   ├── inventory
│   └── test.yml
└── vars                        # The is the folder for role specific variables.
    └── main.yml
```

### Tasks files
Each of these tasks files is a separate playbook but together they create a role which can configure or build a service.

We use a special var called `ansible_facts`, this is information from `ansible.builtin.setup`.
In the next part (5) we will go further into detail about vars and secrets.
To show the output of the special var we use the `ansible.builtin.debug` module.

#### 00_gather_facts.yml
In this playbook we gather all the information that ansible can learn.
This is can be the gather_facts = true toggle in a single playbook.
```bash
---
- name: Gather facts
  ansible.builtin.setup:
    gather_subset:
      - 'all'
```
#### 01_hostname.yml
In this playbook we want to know what distribution the machine is running and which version.
```bash
---
- name: Get distribution
  ansible.builtin.debug: 
    var: ansible_facts.distribution

- name: Get distribution_version
  ansible.builtin.debug:
    var: ansible_facts.distribution_version 

- name: Get hostname
  ansible.builtin.debug: 
    var: ansible_facts.nodename
```
#### 02_ram.yml
We also want to know how much RAM we have and how much is used.
```bash
---
- name: Get free ram
  ansible.builtin.debug: 
    var: ansible_facts.memfree_mb

- name: Get total ram
  ansible.builtin.debug: 
    var: ansible_facts.memtotal_mb
```
#### main.yml
This is the file where every separate playbook comes together to bind the role together.
```bash
---
- name: Get facts
  ansible.builtin.include_tasks: 00_gather_facts.yml

- name: Get hostname
  ansible.builtin.include_tasks: 01_hostname.yml

- name: Get ram
  ansible.builtin.include_tasks: 02_ram.yml
```


### Creating the playbook which runs the role
```bash
touch /Users/sebas/Desktop/ansible/role_book.yml
```

Lets copy the following configurion into the `role_book.yml` file.
Ansible uses the roles part in the configuration to know that it is a role which needs to be run.\
Because this role is in the same directory as the role_book playbook is doesn't matter.
When you place your role somewhere else you need to add a path like `role: <path>/role_name`
```bash
---
- name: playbook
  hosts: localhost
  roles: 
    - role: machine_info
```
We use the same command to run a playbook, but now inside the playbook there is a role defined.
The working of the command is the same, Ansible knows when it needs to search for the main.yml file in the role when the roles tag is used.

```bash
ansible-playbook role_book.yml
```

#### Output
```bash
sebas@eyeofmordor ansible % ansible-playbook role_book.yml 
[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that
the implicit localhost does not match 'all'

PLAY [playbook] ****************************************************************

TASK [Gathering Facts] *********************************************************
ok: [localhost]

TASK [machine_info : Get facts] ************************************************
included: /Users/sebas/Desktop/ansible/machine_info/tasks/00_gather_facts.yml for localhost

TASK [machine_info : Gather facts] *********************************************
ok: [localhost]

TASK [machine_info : Get hostname] *********************************************
included: /Users/sebas/Desktop/ansible/machine_info/tasks/01_hostname.yml for localhost

TASK [machine_info : Get distribution] *****************************************
ok: [localhost] => {
    "ansible_facts.distribution": "MacOSX"
}

TASK [machine_info : Get distribution_version] *********************************
ok: [localhost] => {
    "ansible_facts.distribution_version": "15.2"
}

TASK [machine_info : Get hostname] *********************************************
ok: [localhost] => {
    "ansible_facts.nodename": "eyeofmordor"
}

TASK [machine_info : Get ram] **************************************************
included: /Users/sebas/Desktop/ansible/machine_info/tasks/02_ram.yml for localhost

TASK [machine_info : Get free ram] *********************************************
ok: [localhost] => {
    "ansible_facts.memfree_mb": "6562"
}

TASK [machine_info : Get total ram] *********************************************
ok: [localhost] => {
    "ansible_facts.memtotal_mb": "8192"
}

PLAY RECAP *********************************************************************
localhost                  : ok=10   changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
```

## How to use variables
Variables are a great way of setting informations which can be reused on different places within our playbook or role.
This url does a deepdive in variables [https://spacelift.io/blog/ansible-variables](https://spacelift.io/blog/ansible-variables) and does a great way of explaining how to use it.

### Conclusion
When you when want to keep all the necessary files together for projects or configurations.
Roles is a great solution for this, there is always a playbook needed to call on the role itself.

Stay tuned for the **Part 5: Secrets**!

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NAVIGATION

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            https://ctrl-find.nl/posts/ansible_playbooks/index.txt


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