Introduction to Ansible Playbooks

Ansible playbooks are YAML-formatted configuration files that define a series of tasks to be executed on managed nodes. Unlike ad hoc commands, playbooks provide a repeatable, reusable way to automate complex system configurations and deployments. They are the foundation of Ansible’s infrastructure-as-code approach.

In this tutorial, we’ll create a simple but practical playbook that installs and starts the Apache HTTP Server (httpd) on a target system. This example demonstrates fundamental playbook concepts that you can apply to more complex automation scenarios.

Understanding the HTTPD Installation Playbook

Basic playbook structure and syntax

Below is a complete playbook that installs the httpd package and ensures the service is started and enabled at boot:

---
- hosts: ansiblenode2
  become: yes
  tasks:
  - name: install httpd
    yum:
      name: httpd
      state: latest
  - name: start and enable httpd
    service:
      name: httpd
      state: started
      enabled: yes   

Playbook Component Breakdown

Understanding each section of the playbook:

1. YAML Header (—)

The three dashes indicate the start of a YAML document. This is standard YAML syntax and should begin every playbook.

2. Hosts Declaration

- hosts: ansiblenode2

This line specifies which hosts or host groups the playbook will target. In this example, we’re targeting a single host named “ansiblenode2”. You could also use:

• all – Target all hosts in inventory
• webservers – Target a specific group
• web* – Use wildcards for pattern matching

3. Privilege Escalation

become: yes

This directive tells Ansible to execute tasks with sudo privileges (become root). Installing packages and managing services requires root access, so this is essential for our playbook.

4. Tasks Section

The tasks section contains an ordered list of actions to be performed. Each task should have a descriptive name and use an Ansible module.

Task 1: Installing HTTPD Package

Using the yum module to install Apache

- name: install httpd
  yum:
    name: httpd
    state: latest

Parameters explained:

• name – Unique, descriptive identifier for the task (shown in output)
• yum – Module for managing packages on RHEL/CentOS systems
• name: httpd – Package name to install
• state: latest – Ensures the latest version is installed

Alternative state options:

• state: present – Install if not already present (recommended for production)
• state: absent – Remove the package if installed
• state: latest – Install or upgrade to the latest version

Task 2: Starting and Enabling HTTPD Service

Using the service module to manage Apache daemon

- name: start and enable httpd
  service:
    name: httpd
    state: started
    enabled: yes

Parameters explained:

• service – Module for managing system services
• name: httpd – Service name to manage
• state: started – Ensures the service is running
• enabled: yes – Configures service to start automatically at boot

This task is idempotent, meaning it can be run multiple times safely. If the service is already running, Ansible will not make any changes.

Running the Playbook

How to execute your playbook

Save the playbook content to a file (e.g., install_httpd.yml) and run it with the ansible-playbook command:

[ansible@ansiblecontrolnode ~]$ ansible-playbook install_httpd.yml

PLAY [ansiblenode2] ****************************************************

TASK [Gathering Facts] *************************************************
ok: [ansiblenode2]

TASK [install httpd] ***************************************************
changed: [ansiblenode2]

TASK [start and enable httpd] ******************************************
changed: [ansiblenode2]

PLAY RECAP *************************************************************
ansiblenode2               : ok=3    changed=2    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

The output shows:

• Gathering Facts: Ansible automatically collects system information
• install httpd: Package installation task (changed status indicates it was installed)
• start and enable httpd: Service management task (changed indicates it was started)
• PLAY RECAP: Summary showing 3 tasks succeeded with 2 changes

Verifying the Installation

Checking if Apache is running

After the playbook completes, verify that httpd is installed and running:

# Check httpd service status
ansible ansiblenode2 -b -m shell -a "systemctl status httpd"

# Verify httpd is listening on port 80
ansible ansiblenode2 -b -m shell -a "netstat -tulpn | grep :80"

# Test the web server
curl http://ansiblenode2

Enhanced Playbook with Firewall Configuration

Adding firewall rules for complete setup

For a production-ready installation, you should also configure the firewall to allow HTTP traffic:

---
- hosts: ansiblenode2
  become: yes
  tasks:
  - name: install httpd
    yum:
      name: httpd
      state: present
      
  - name: start and enable httpd
    service:
      name: httpd
      state: started
      enabled: yes
      
  - name: allow http through firewall
    firewalld:
      service: http
      permanent: yes
      state: enabled
      immediate: yes
      
  - name: create a simple index.html
    copy:
      content: "
Welcome to {{ ansible_hostname }}
"
      dest: /var/www/html/index.html
      owner: apache
      group: apache
      mode: 0644

This enhanced version includes:

• Firewall configuration using the firewalld module
• Creation of a custom index.html page
• Use of Ansible variables ({{ ansible_hostname }})

Playbook Best Practices

• Use descriptive task names: Clear names make debugging easier
• Prefer ‘present’ over ‘latest’: Avoid unexpected upgrades in production
• Always enable services: Ensure services survive reboots
• Check syntax before running: Use ansible-playbook --syntax-check playbook.yml
• Test with –check mode: Dry-run with ansible-playbook --check playbook.yml
• Use version control: Store playbooks in Git for tracking changes
• Add handlers for service restarts: Only restart services when configuration changes

Common Issues and Troubleshooting

Package installation fails:

• Ensure yum repositories are configured properly
• Check internet connectivity on target nodes
• Verify sudo privileges are configured correctly

Service won’t start:

• Check for port conflicts (another service using port 80)
• Review SELinux context and permissions
• Examine logs: /var/log/httpd/error_log

Firewall blocking connections:

• Verify firewalld is running: systemctl status firewalld
• Check firewall rules: firewall-cmd --list-all
• Ensure http service is allowed

Conclusion

This simple playbook demonstrates the fundamental concepts of Ansible automation: declarative configuration, idempotency, and infrastructure as code. By installing and configuring Apache HTTP Server, you’ve learned how to combine multiple modules into a cohesive automation workflow.

As you become more comfortable with playbooks, you can expand this example to include:

• Virtual host configurations
• SSL certificate deployment
• Custom Apache modules
• Load balancer integration
• Monitoring and logging setup

The skills you’ve learned here form the foundation for managing complex infrastructure with Ansible. Keep practicing, and soon you’ll be automating entire application stacks!