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Ansible Playbook Guide
Ansible Playbooks are YAML files that automate server configuration, deployment, and management. This guide provides instructions on running a playbook and includes examples to help you get started.
Running an Ansible Playbook
To execute an Ansible Playbook, use the following command:
ansible-playbook <playbook.yaml> -i <inventory-file.ini>
<playbook.yaml>: Path to your playbook file.<inventory-file.ini>: Path to your inventory file (can be in INI or YAML format).
Example Playbooks
1. Simple APT Cache Update
This playbook updates the APT package cache on all specified hosts.
- name: Update APT Cache Playbook
hosts: all # Run on all hosts defined in the inventory
become: yes # Use sudo for elevated privileges
tasks:
- name: Update apt-cache
ansible.builtin.apt:
update_cache: yes
2. Update APT Cache and Install Nginx
This playbook updates the APT cache and installs the Nginx web server on all specified hosts.
- name: Install Nginx and Update APT Cache
hosts: all # Run on all hosts defined in the inventory
become: yes # Use sudo for elevated privileges
tasks:
- name: Update apt-cache and install Nginx
ansible.builtin.apt:
name: nginx
state: present
update_cache: yes
3. Install Nginx and Copy Configuration File
This playbook installs Nginx and copies a custom configuration file from the Ansible server to the target hosts.
- name: Install Nginx and Copy Configuration
hosts: all # Run on all hosts defined in the inventory
become: yes # Use sudo for elevated privileges
tasks:
- name: Update apt-cache and install Nginx
ansible.builtin.apt:
name: nginx
state: present
update_cache: yes
- name: Copy Nginx configuration file
ansible.builtin.copy:
src: /root/ansible/nginx.conf # Source file on Ansible server
dest: /etc/nginx/nginx.conf # Destination file on the target hosts
4. Full Nginx Deployment: Install, Configure, and Restart
This playbook demonstrates a full Nginx deployment, including updating the APT cache, installing Nginx, copying a configuration file, and restarting the Nginx service.
- name: Full Nginx Deployment
hosts: all # Run on all hosts defined in the inventory
become: yes # Use sudo for elevated privileges
tasks:
- name: Update apt-cache and install Nginx
ansible.builtin.apt:
name: nginx
state: present
update_cache: yes
- name: Copy Nginx configuration file
ansible.builtin.copy:
src: /root/ansible/nginx.conf
dest: /etc/nginx/nginx.conf
notify: Restart Nginx # Triggers the handler to restart Nginx
handlers:
- name: Restart Nginx
ansible.builtin.service:
name: nginx
state: restarted
Key Components Explained
hosts: all: Specifies that the playbook should run on all hosts listed in the inventory file.become: yes: Ensures tasks requiring elevated privileges (sudo) are executed as the root user.- Tasks:
Update apt-cache: Uses the APT module to update the package cache.Install Nginx: Installs the Nginx web server.Copy Configuration File: Copies a custom configuration file to the appropriate directory on the target hosts.Restart Nginx: Restarts the Nginx service to apply the new configuration.
Running the Playbooks
Save the desired playbook as a YAML file (e.g., deploy_nginx.yaml), and run it using:
ansible-playbook deploy_nginx.yaml -i inventory.ini
Ensure that your inventory file (inventory.ini) includes all necessary hosts and connection details.
Additional Examples
Show Debug Message
Use the debug module to display a message during playbook execution. This is useful for testing or providing feedback within your playbooks.
- name: Show Debug Message
ansible.builtin.debug:
msg: "Test Message"
Use a Shell Command
Run a shell command and capture the output for further use within the playbook.
- name: Execute Shell Command
ansible.builtin.shell:
cmd: echo "Hello, Ansible!"
register: shell_output # Register the command output as a variable
- name: Display Shell Output
ansible.builtin.debug:
msg: "Output is: {{ shell_output.stdout }}" # Display the command output
Playbook with Conditional Statements
This playbook demonstrates the use of conditional statements to check if a file exists and take action based on the result.
- name: Check if File Exists
ansible.builtin.shell:
cmd: ls /path/to/file
register: file_output
ignore_errors: yes
- name: File Exists
ansible.builtin.debug:
msg: "File exists"
when: file_output.rc == 0 # Only runs if the previous command was successful
- name: File Does Not Exist
ansible.builtin.debug:
msg: "File does not exist"
when: file_output.rc != 0 # Runs if the previous command failed
Check File Existence Using the stat Module
A more reliable method to check if a file exists using the stat module.
- name: Check if File Exists
ansible.builtin.stat:
path: /path/to/file
register: file_stat
- name: File Exists
ansible.builtin.debug:
msg: "File exists"
when: file_stat.stat.exists # Checks if the file exists
- name: File Does Not Exist
ansible.builtin.debug:
msg: "File does not exist"
when: not file_stat.stat.exists # Checks if the file does not exist
Standalone Nginx Installation
This playbook installs Nginx on both Debian-based and RedHat-based systems by detecting the operating system family.
- name: Install Nginx
hosts: all
become: yes
tasks:
- name: Install on Debian-based systems
ansible.builtin.apt:
name: nginx
state: present
when: ansible_facts['os_family'] == "Debian" # Conditional based on OS family
- name: Install on RedHat-based systems
ansible.builtin.yum:
name: nginx
state: present
when: ansible_facts['os_family'] == "RedHat" # Conditional based on OS family
Create a User
This playbook checks if a user exists and creates the user if it does not.
- name: Manage User Account
hosts: all
become: yes
tasks:
- name: Check if user exists
ansible.builtin.command:
cmd: id new_user
register: user_data
ignore_errors: yes
- name: Create user
ansible.builtin.user:
name: new_user
state: present
when: user_data.rc != 0 # Only create the user if they do not already exist
Install Multiple Packages
These examples show how to install multiple packages, either using a loop or as a list.
Using a Loop:
- name: Install Multiple Packages with Loop
hosts: all
become: yes
tasks:
- name: Install packages
ansible.builtin.apt:
name: "{{ item }}"
state: present
loop:
- vim
- git
- nginx
Using a List:
- name: Install Multiple Packages as a List
hosts: all
become: yes
tasks:
- name: Install packages
ansible.builtin.apt:
name: ["vim", "nginx", "git"]
state: present
Create Multiple Users
This playbook creates multiple users with different groups.
- name: Create Multiple Users
hosts: all
become: yes
tasks:
- name: Create users
ansible.builtin.user:
name: "{{ item.name }}"
group: "{{ item.group }}"
state: "{{ item.state }}"
loop:
- { name: "radin", state: "present", group: "sudo" }
- { name: "test", state: "present", group: "dev" }
- { name: "test2", state: "present", group: "test_unit" }