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RHCE Exam Topics & Skills

The RHCE exam (EX294) tests your ability to automate RHEL systems using Ansible. Here's what you need to master:

Ansible Core Concepts

Understand Ansible architecture and basic operations:

• Installing and configuring Ansible on control nodes
• Managing inventory files (static and dynamic)
• Configuring ansible.cfg for custom settings
• Running ad-hoc commands for quick tasks

Key Commands:

# Install Ansible
dnf install ansible-core

# Run ad-hoc command
ansible webservers -m ping
ansible all -m command -a "uptime"

# Check inventory
ansible-inventory --list

Playbook Development

Create and manage Ansible playbooks for automation:

• Writing YAML playbooks with proper syntax
• Using variables, facts, and registered variables
• Implementing conditionals with when statements
• Looping with loop, with_items, and with_dict
• Error handling with block, rescue, and always

Example Playbook:

---
- name: Configure web servers
  hosts: webservers
  become: yes
  vars:
    http_port: 80
    
  tasks:
    - name: Install Apache
      ansible.builtin.dnf:
        name: httpd
        state: present
        
    - name: Start and enable httpd
      ansible.builtin.service:
        name: httpd
        state: started
        enabled: yes
        
    - name: Open firewall port
      ansible.posix.firewalld:
        port: "{{ http_port }}/tcp"
        permanent: yes
        state: enabled
        immediate: yes

Ansible Roles

Structure automation code using roles:

• Creating role directory structures with ansible-galaxy init
• Using tasks, handlers, templates, files, and vars directories
• Managing role dependencies in meta/main.yml
• Downloading roles from Ansible Galaxy

Templates and Jinja2

Create dynamic configuration files:

• Writing Jinja2 templates (.j2 files)
• Using variables and filters in templates
• Conditional logic within templates
• Iterating over lists and dictionaries

Example Template:

# /etc/httpd/conf/httpd.conf
Listen {{ http_port }}
ServerName {{ ansible_fqdn }}

{% for vhost in virtual_hosts %}
<VirtualHost *:{{ http_port }}>
    ServerName {{ vhost.name }}
    DocumentRoot {{ vhost.docroot }}
</VirtualHost>
{% endfor %}

Ansible Vault

Manage secrets securely:

• Encrypting files with ansible-vault create/encrypt
• Using encrypted variables in playbooks
• Managing vault passwords with password files
• Rekeying vaults for password rotation

Key Commands:

# Create encrypted file
ansible-vault create secrets.yml

# Edit encrypted file
ansible-vault edit secrets.yml

# Run playbook with vault
ansible-playbook site.yml --ask-vault-pass
ansible-playbook site.yml --vault-password-file=.vault_pass

RHEL System Roles

Use Red Hat's supported roles for common tasks:

• rhel-system-roles.network - Network configuration
• rhel-system-roles.timesync - NTP/Chrony configuration
• rhel-system-roles.storage - Disk and LVM management
• rhel-system-roles.selinux - SELinux configuration
• rhel-system-roles.firewall - Firewall management