RHCE 9.0 Practice Exam: Modifying the /etc/issue File Based on Host Groups Using Ansible

📌 Article Overview

This tutorial is designed for RHCE 9.0 certification candidates and explains how to use Ansible to modify the /etc/issue file dynamically based on host group membership.

💡 What You Will Learn:

✅ How to modify files using Ansible’s copy module
✅ How to apply conditional logic based on inventory groups
✅ How to verify the correct content replacement in /etc/issue

📜 1. Task Requirements

📍 1.1. Problem Statement

1. Create a playbook named /home/greg/ansible/issue.yml.
2. Run the playbook on all managed hosts.
3. Modify /etc/issue with the following content based on group membership:

Hosts in the prod group should contain:

Production

Hosts in the test group should contain:

Test

Hosts in the dev group should contain:

Development

📜 2. Gathering Information About Hosts

Before writing the playbook, verify the inventory group structure.

📍 2.1. Check Group Membership

$ ansible dev -m debug -a 'var=inventory_hostname'
$ ansible dev -m debug -a 'var=groups'
$ ansible dev -m debug -a 'var=groups.dev'

📌 This ensures the hosts are correctly assigned to the dev, test, and prod groups.

📍 2.2. Check the File Module Documentation

$ ansible-doc copy
$ ansible-doc stat

📌 This provides details on how to use Ansible's copy module to modify files.

📜 3. Writing the Ansible Playbook

📍 3.1. Create the Playbook File

$ vim /home/greg/ansible/issue.yml

📄 Add the Following Content

---
- name: Modify /etc/issue based on host group
  hosts: all
  become: yes
  tasks:

    - name: Set /etc/issue for Development hosts
      ansible.builtin.copy:
        content: 'Development\n'
        dest: /etc/issue
        mode: '0644'
      when: inventory_hostname in groups['dev']

    - name: Set /etc/issue for Test hosts
      ansible.builtin.copy:
        content: 'Test\n'
        dest: /etc/issue
        mode: '0644'
      when: inventory_hostname in groups['test']

    - name: Set /etc/issue for Production hosts
      ansible.builtin.copy:
        content: 'Production\n'
        dest: /etc/issue
        mode: '0644'
      when: inventory_hostname in groups['prod']

📌 Explanation:

• Uses Ansible’s copy module to modify /etc/issue with the correct text.
• Applies conditions (when:) to target specific groups (dev, test, prod).
• Ensures proper file permissions (0644).

💾 Save and exit: (ESC → :wq)

📜 4. Running the Playbook

📍 4.1. Execute the Playbook

$ ansible-navigator run /home/greg/ansible/issue.yml -m stdout

📌 Expected Output

PLAY [Modify /etc/issue based on host group] **********************************

TASK [Set /etc/issue for Development hosts] ***********************************
changed: [node1]
skipping: [node3]
skipping: [node5]

TASK [Set /etc/issue for Test hosts] *****************************************
skipping: [node1]
changed: [node3]
skipping: [node5]

TASK [Set /etc/issue for Production hosts] ************************************
skipping: [node1]
skipping: [node3]
changed: [node5]

PLAY RECAP ********************************************************************
node1 : ok=1 changed=1 unreachable=0 failed=0
node3 : ok=1 changed=1 unreachable=0 failed=0
node5 : ok=1 changed=1 unreachable=0 failed=0

✅ Each host received the correct /etc/issue file based on its group!

📜 5. Verifying /etc/issue Content

📍 5.1. Check File Content on All Hosts

$ ansible dev -a 'cat /etc/issue'
$ ansible test -a 'cat /etc/issue'
$ ansible prod -a 'cat /etc/issue'

📌 Expected Output:

# For dev group:
Development

# For test group:
Test

# For prod group:
Production

✅ Each host has the correct content in /etc/issue!

📜 6. Common Issues & Troubleshooting

🔴 Issue 1: Some Hosts Did Not Receive the Correct /etc/issue

✅ Solution:

Check if Ansible is correctly identifying the host groups:

$ ansible all -m debug -a 'var=groups'

Check if the affected hosts are assigned to the correct inventory group:

$ ansible-inventory --graph

🔴 Issue 2: /etc/issue Is Not Changing

✅ Solution:

Check file permissions:

$ ls -l /etc/issue

If permissions are incorrect, rerun the playbook with become: yes.

Ensure the copy module is correctly writing to the file:

$ ansible all -m stat -a 'path=/etc/issue'

🔴 Issue 3: Playbook Fails with Permission Errors

✅ Solution:

1. Ensure become: yes is enabled in the playbook.

Manually check if Ansible has root privileges:

$ ansible all -m shell -a 'whoami'

If it returns root, permissions should be fine. If it returns another user, try running the playbook with:

$ ansible-playbook /home/greg/ansible/issue.yml --become

🚀 Congratulations! You have successfully used Ansible to modify the /etc/issue file dynamically based on host groups! 🚀
📢 If you found this guide helpful, share it with your RHCE 9.0 study group! 📢

🔥 Good luck on your RHCE 9.0 exam! 🔥