Register Red Hat Enterprise Linux and attach a subscription with Ansible

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An early step in our deployment process for Red Hat Enterprise Linux (RHEL) systems involves registering the system and attaching an appropriate subscription. To automate these two steps, I’m using an Ansible role, which I’d like to share with you.

My environment

In my environment, RHEL runs mainly within different virtualization clusters, and occasionally on dedicated servers (bare metal). We use the following subscriptions for development and production:

• Red Hat Developer Subscription
• Red Hat Enterprise Linux Server, Standard (physical or virtual nodes)
• Red Hat Enterprise Linux for Virtual Datacenters, Standard

The register-rhel-subscription role

My role is minimalistic and has the following structure:

# tree roles/register-rhel-subscription
roles/register-rhel-subscription
|-- defaults
| `-- main.yml
|-- tasks
| `-- main.yml

tasks/main.yml

The Ansible module redhat_subscription manages a system’s registration and subscription with the subscription-manager command. Start by creating your activation key in the Customer Portal. This key enables registration without the need to input the username and password.

Assign this key to the parameter activationkey, like so:

activationkey: "{{ org_activationkey }}"

In the above code, the content of the variable org_activationkey is passed to the parameter. How and where this variable is defined will be explained in the next section.

You also need to add your organization’s ID into org_id. You can find this information with the following:

sudo subscription-manager identity

Then, declares the desired target state through:

state: present

In this case, the system should be registered and a subscription attached. If you change this parameter to state: absent, the system will be unregistered accordingly.

Here is what the code looks like when it’s all put together:

---
# tasks file for register-rhel-subscription
# Register System and add Subcription
- name: Register system and add subscription
  redhat_subscription:
    activationkey: "{{ org_activationkey }}"
    org_id: 1234567
    state: present

defaults/main.yml

In this file, we define the default value for the variable org_activationkey:

---
# defaults file for register-rhel-subscription
org_activationkey: "my-datacenter-sub"

The value specified in this file can be overwritten in, for example, host_vars and group_vars (see Using Variables). You can use the group memberships in the Ansible inventory to control which subscription is assigned to a host or to a group of hosts.

Example playbook

With the steps above completed, you can now add the register-rhel-subscription role to your playbook:

---
- hosts: all
  tasks:
  - name: Group by OS
    group_by:
      key=os_{{ ansible_distribution }}
      changed_when: False

  - hosts: os_RedHat
    roles: - register-rhel-subscription

Conclusion

So far this solution makes a robust impression, and writing this text took much longer than the actual task. This is a small and simple example of how Ansible could make your Sysadmin Day somewhat easier.