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Ansible Galaxy: Collections and Roles

In this chapter you will learn how to use, install, and manage Ansible roles and collections.


Objectives: In this chapter you will learn how to:

✔ install and manage collections;
✔ install and manage roles;.

🏁 ansible, ansible-galaxy, roles, collections

Knowledge: ⭐ ⭐
Complexity: ⭐ ⭐ ⭐

Reading time: 40 minutes


Ansible Galaxy provides Ansible Roles and Collections from the Ansible Community.

The elements provided can be referenced in the playbooks and used out of the box

ansible-galaxy command

The ansible-galaxy command manages roles and collections using galaxy.ansible.com.

  • To manage roles:
ansible-galaxy role [import|init|install|login|remove|...]
Sub-commands Observations
install installs a role.
remove remove one or more roles.
list display the name and the version of installed roles.
info display information about a role.
init generate a skeleton of a new role.
import import a role from the galaxy web site. Requires a login.
  • To manage collections:
ansible-galaxy collection [import|init|install|login|remove|...]
Sub-commands Observations
init generate a skeleton of a new collection.
install installs a collection.
list display the name and the version of installed collections.

Ansible Roles

An Ansible role is a unit that promotes the reusability of playbooks.

Note

More information can be found here

Installing useful Roles

In order to highlight the interest of using roles, I suggest you to use the alemorvan/patchmanagement role, which will allow you to perform a lot of tasks (pre-update or post-update for example) during your update process, in only a few lines of code.

You can check the code in the github repo of the role here.

  • Install the role. This needs only one command:
ansible-galaxy role install alemorvan.patchmanagement
  • Create a playbook to include the role:
- name: Start a Patch Management
  hosts: ansible_clients
  vars:
    pm_before_update_tasks_file: custom_tasks/pm_before_update_tasks_file.yml
    pm_after_update_tasks_file: custom_tasks/pm_after_update_tasks_file.yml

  tasks:
    - name: "Include patchmanagement"
      include_role:
        name: "alemorvan.patchmanagement"

With this role, you can add your own tasks for all your inventory or for only your targeted node.

Let's create tasks that will be run before and after the update process:

  • Create the custom_tasks folder:
mkdir custom_tasks
  • Create the custom_tasks/pm_before_update_tasks_file.yml (feel free to change the name and the content of this file)
---
- name: sample task before the update process
  debug:
    msg: "This is a sample tasks, feel free to add your own test task"
  • Create the custom_tasks/pm_after_update_tasks_file.yml (feel free to change the name and the content of this file)
---
- name: sample task after the update process
  debug:
    msg: "This is a sample tasks, feel free to add your own test task"

And launch your first Patch Management:

ansible-playbook patchmanagement.yml

PLAY [Start a Patch Management] *************************************************************************

TASK [Gathering Facts] **********************************************************************************
ok: [192.168.1.11]

TASK [Include patchmanagement] **************************************************************************

TASK [alemorvan.patchmanagement : MAIN | Linux Patch Management Job] ************************************
ok: [192.168.1.11] => {
    "msg": "Start 192 patch management"
}

...

TASK [alemorvan.patchmanagement : sample task before the update process] ********************************
ok: [192.168.1.11] => {
    "msg": "This is a sample tasks, feel free to add your own test task"
}

...

TASK [alemorvan.patchmanagement : MAIN | We can now patch] **********************************************
included: /home/ansible/.ansible/roles/alemorvan.patchmanagement/tasks/patch.yml for 192.168.1.11

TASK [alemorvan.patchmanagement : PATCH | Tasks depends on distribution] ********************************
ok: [192.168.1.11] => {
    "ansible_distribution": "Rocky"
}

TASK [alemorvan.patchmanagement : PATCH | Include tasks for CentOS & RedHat tasks] **********************
included: /home/ansible/.ansible/roles/alemorvan.patchmanagement/tasks/linux_tasks/redhat_centos.yml for 192.168.1.11

TASK [alemorvan.patchmanagement : RHEL CENTOS | yum clean all] ******************************************
changed: [192.168.1.11]

TASK [alemorvan.patchmanagement : RHEL CENTOS | Ensure yum-utils is installed] **************************
ok: [192.168.1.11]

TASK [alemorvan.patchmanagement : RHEL CENTOS | Remove old kernels] *************************************
skipping: [192.168.1.11]

TASK [alemorvan.patchmanagement : RHEL CENTOS | Update rpm package with yum] ****************************
ok: [192.168.1.11]

TASK [alemorvan.patchmanagement : PATCH | Inlude tasks for Debian & Ubuntu tasks] ***********************
skipping: [192.168.1.11]

TASK [alemorvan.patchmanagement : MAIN | We can now reboot] *********************************************
included: /home/ansible/.ansible/roles/alemorvan.patchmanagement/tasks/reboot.yml for 192.168.1.11

TASK [alemorvan.patchmanagement : REBOOT | Reboot triggered] ********************************************
ok: [192.168.1.11]

TASK [alemorvan.patchmanagement : REBOOT | Ensure we are not in rescue mode] ****************************
ok: [192.168.1.11]

...

TASK [alemorvan.patchmanagement : FACTS | Insert fact file] *********************************************
ok: [192.168.1.11]

TASK [alemorvan.patchmanagement : FACTS | Save date of last PM] *****************************************
ok: [192.168.1.11]

...

TASK [alemorvan.patchmanagement : sample task after the update process] *********************************
ok: [192.168.1.11] => {
    "msg": "This is a sample tasks, feel free to add your own test task"
}

PLAY RECAP **********************************************************************************************
192.168.1.11               : ok=31   changed=1    unreachable=0    failed=0    skipped=4    rescued=0    ignored=0  

Pretty easy for such a complex process, isn't it?

This is just one example of what can be done using roles made available by the community. Have a look at galaxy.ansible.com to discover the roles that could be useful for you!

You can also create your own roles for your own needs and publish them on the Internet if you feel like it. This is what we will briefly cover in the next chapter.

Introduction to Role development

A role skeleton, serving as a starting point for custom role development, can be generated by the ansible-galaxy command:

$ ansible-galaxy role init rocky8
- Role rocky8 was created successfully

The command will generate the following tree structure to contain the rocky8 role:

tree rocky8/
rocky8/
├── defaults
│   └── main.yml
├── files
├── handlers
│   └── main.yml
├── meta
│   └── main.yml
├── README.md
├── tasks
│   └── main.yml
├── templates
├── tests
│   ├── inventory
│   └── test.yml
└── vars
    └── main.yml

8 directories, 8 files

Roles allow you to do away with the need to include files. There is no need to specify file paths or include directives in playbooks. You just have to specify a task, and Ansible takes care of the inclusions.

The structure of a role is fairly obvious to understand.

Variables are simply stored either in vars/main.yml if the variables are not to be overridden, or in default/main.yml if you want to leave the possibility of overriding the variable content from outside your role.

The handlers, files, and templates needed for your code are stored in handlers/main.yml, files and templates respectively.

All that remains is to define the code for your role's tasks in tasks/main.yml.

Once all this is working well, you can use this role in your playbooks. You will be able to use your role without worrying about the technical aspect of its tasks, while customizing its operation with variables.

Practical work: create a first simple role

Let's implement this with a "go anywhere" role that will create a default user and install software packages. This role can be systematically applied to all your servers.

Variables

We will create a rockstar user on all of our servers. As we don't want this user to be overridden, let's define it in the vars/main.yml:

---
rocky8_default_group:
  name: rockstar
  gid: 1100
rocky8_default_user:
  name: rockstar
  uid: 1100
  group: rockstar

We can now use those variables inside our tasks/main.yml without any inclusion.

---
- name: Create default group
  group:
    name: "{{ rocky8_default_group.name }}"
    gid: "{{ rocky8_default_group.gid }}"

- name: Create default user
  user:
    name: "{{ rocky8_default_user.name }}"
    uid: "{{ rocky8_default_user.uid }}"
    group: "{{ rocky8_default_user.group }}"

To test your new role, let's create a test-role.yml playbook in the same directory as your role:

---
- name: Test my role
  hosts: localhost

  roles:

    - role: rocky8
      become: true
      become_user: root

and launch it:

ansible-playbook test-role.yml

PLAY [Test my role] ************************************************************************************

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

TASK [rocky8 : Create default group] *******************************************************************
changed: [localhost]

TASK [rocky8 : Create default user] ********************************************************************
changed: [localhost]

PLAY RECAP *********************************************************************************************
localhost                  : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   

Congratulations! You are now able to create great things with a playbook of only a few lines.

Let's see the use of default variables.

Create a list of packages to install by default on your servers and an empty list of packages to uninstall. Edit the defaults/main.yml files and add those two lists:

rocky8_default_packages:
  - tree
  - vim
rocky8_remove_packages: []

and use them in your tasks/main.yml:

- name: Install default packages (can be overridden)
  package:
    name: "{{ rocky8_default_packages }}"
    state: present

- name: "Uninstall default packages (can be overridden) {{ rocky8_remove_packages }}"
  package:
    name: "{{ rocky8_remove_packages }}"
    state: absent

Test your role with the help of the playbook previously created:

ansible-playbook test-role.yml

PLAY [Test my role] ************************************************************************************

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

TASK [rocky8 : Create default group] *******************************************************************
ok: [localhost]

TASK [rocky8 : Create default user] ********************************************************************
ok: [localhost]

TASK [rocky8 : Install default packages (can be overridden)] ********************************************
ok: [localhost]

TASK [rocky8 : Uninstall default packages (can be overridden) []] ***************************************
ok: [localhost]

PLAY RECAP *********************************************************************************************
localhost                  : ok=5    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   

You can now override the rocky8_remove_packages in your playbook and uninstall for example cockpit:

---
- name: Test my role
  hosts: localhost
  vars:
    rocky8_remove_packages:
      - cockpit

  roles:

    - role: rocky8
      become: true
      become_user: root
ansible-playbook test-role.yml

PLAY [Test my role] ************************************************************************************

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

TASK [rocky8 : Create default group] *******************************************************************
ok: [localhost]

TASK [rocky8 : Create default user] ********************************************************************
ok: [localhost]

TASK [rocky8 : Install default packages (can be overridden)] ********************************************
ok: [localhost]

TASK [rocky8 : Uninstall default packages (can be overridden) ['cockpit']] ******************************
changed: [localhost]

PLAY RECAP *********************************************************************************************
localhost                  : ok=5    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   

Obviously, there is no limit to how much you can improve your role. Imagine that for one of your servers, you need a package that is in the list of those to be uninstalled. You could then, for example, create a new list that can be overridden and then remove from the list of packages to be uninstalled those in the list of specific packages to be installed by using the jinja difference() filter.

- name: "Uninstall default packages (can be overridden) {{ rocky8_remove_packages }}"
  package:
    name: "{{ rocky8_remove_packages | difference(rocky8_specifics_packages) }}"
    state: absent

Ansible Collections

Collections are a distribution format for Ansible content that can include playbooks, roles, modules, and plugins.

Note

More information can be found here

To install or upgrade a collection:

ansible-galaxy collection install namespace.collection [--upgrade]

You can then use the newly installed collection using its namespace and name before the module's name or role's name:

- import_role:
    name: namespace.collection.rolename

- namespace.collection.modulename:
    option1: value

You can find a collection index here.

Let's install the community.general collection:

ansible-galaxy collection install community.general
Starting galaxy collection install process
Process install dependency map
Starting collection install process
Downloading https://galaxy.ansible.com/download/community-general-3.3.2.tar.gz to /home/ansible/.ansible/tmp/ansible-local-51384hsuhf3t5/tmpr_c9qrt1/community-general-3.3.2-f4q9u4dg
Installing 'community.general:3.3.2' to '/home/ansible/.ansible/collections/ansible_collections/community/general'
community.general:3.3.2 was installed successfully

We can now use the newly available module yum_versionlock:

- name: Start a Patch Management
  hosts: ansible_clients
  become: true
  become_user: root
  tasks:

    - name: Ensure yum-versionlock is installed
      package:
        name: python3-dnf-plugin-versionlock
        state: present

    - name: Prevent kernel from being updated
      community.general.yum_versionlock:
        state: present
        name: kernel
      register: locks

    - name: Display locks
      debug:
        var: locks.meta.packages                            
ansible-playbook versionlock.yml

PLAY [Start a Patch Management] *************************************************************************

TASK [Gathering Facts] **********************************************************************************
ok: [192.168.1.11]

TASK [Ensure yum-versionlock is installed] **************************************************************
changed: [192.168.1.11]

TASK [Prevent kernel from being updated] ****************************************************************
changed: [192.168.1.11]

TASK [Display locks] ************************************************************************************
ok: [192.168.1.11] => {
    "locks.meta.packages": [
        "kernel"
    ]
}

PLAY RECAP **********************************************************************************************
192.168.1.11               : ok=4    changed=2    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   

Creating your own collection

As with roles, you are able to create your own collection with the help of the ansible-galaxy command:

ansible-galaxy collection init rocky8.rockstarcollection
- Collection rocky8.rockstarcollection was created successfully
tree rocky8/rockstarcollection/
rocky8/rockstarcollection/
├── docs
├── galaxy.yml
├── plugins
│   └── README.md
├── README.md
└── roles

You can then store your own plugins or roles inside this new collection.

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