Execute a Shell Script on a Remote Server with Ansible Script Module

Automating tasks across multiple servers can be efficiently handled using Ansible. One of the powerful features Ansible offers is the ability to execute shell scripts on remote servers using the ansible.builtin.script module. It allows you to run custom scripts on remote machines as part of your automation tasks. This is useful when you have specific commands or scripts that can’t be easily handled by Ansible’s built-in modules.

This guide will explain how to use Ansible script module to execute a shell script on a remote server with practical examples.

Basic Syntax

The ansible.builtin.script module allows you to execute local scripts on remote nodes. The script is first transferred to the remote node and then executed there.

Here’s the basic syntax for using the ansible.builtin.script module:

- name: Run a local script on the remote host
  ansible.builtin.script:
    cmd: /path/to/local/script.sh

Explanation.

• name: A description of the task.
• ansible.builtin.script: The module used to execute a script.
• cmd: The path to the script you want to run on the remote host. This should be a path to a script file on the local machine where Ansible is running.

Example 1: Executing a Simple Shell Script

Let’s start with a simple example where we execute a basic shell script on a remote server.

Create a simple shell script named hello_world.sh:

#!/bin/bash
echo "Hello, World!"

Make the script executable:

 # chmod +x hello_world.sh

Create an Ansible playbook named execute_script.yml:

---
- name: Execute a shell script on a remote server
  hosts: all
  become: yes
  tasks:
    - name: Run hello_world.sh script
      ansible.builtin.script:
        cmd: ./hello_world.sh
      register: script_output

    - name: Print script output
      debug:
        var: script_output.stdout

Execute the playbook with the following command:

 # ansible-playbook execute_script.yml

After running the playbook, you should see the output from the script:

Example 2: Passing Arguments to the Script

Sometimes, you may need to pass arguments to your script. Here’s how you can do that.

1. Create a script named greet_user.sh:

#!/bin/bash
echo "Hello, $1!"

2. Make the script executable:

 # chmod +x greet_user.sh

3. Create an Ansible playbook named execute_script_with_args.yml:

---
- name: Execute a shell script with arguments on a remote server
  hosts: all
  become: yes
  tasks:
    - name: Run greet_user.sh script with argument
      ansible.builtin.script:
        cmd: ./greet_user.sh "Ansible User"
      register: script_output

    - name: Print script output
      debug:
        var: script_output.stdout

4. Execute the playbook with the following command:

 # ansible-playbook execute_script_with_args.yml

After running the playbook, you should see the output from the script:

TASK [Print script output] ******************************************************************
ok: [remote_server] => {
    "script_output.stdout": "Hello, Ansible User!"
}

Example 3: Conditional Execution Based on Script Output

You can use the script module to run the script and then use the when statement to perform actions based on the script’s result.

1.  Create a script named check_service.sh:

#!/bin/bash
service_name=$1
if systemctl is-active --quiet $service_name; then
  echo "$service_name is running"
else
  echo "$service_name is not running"
  exit 1
fi

2. Use the chmod command to make the script executable:

 # chmod +x check_service.sh

3. Create an Ansible playbook named execute_script_with_conditional.yml:

---
- name: Execute a shell script with conditional actions on a remote server
  hosts: all
  become: yes
  tasks:
    - name: Check if a service is running
      ansible.builtin.script:
        cmd: ./check_service.sh sshd
      register: script_output
      ignore_errors: yes

    - name: Print script output
      debug:
        var: script_output.stdout

    - name: Handle service not running
      ansible.builtin.command:
        cmd: systemctl start sshd
      when: script_output.rc != 0

4. Execute the playbook with the following command:

 # ansible-playbook execute_script_with_conditional.yml

After running the playbook, you should see the output from the script, and if the service is not running, Ansible will attempt to start it:

TASK [Print script output] ******************************************************************
ok: [remote_server] => {
    "script_output.stdout": "sshd is not running"
}

TASK [Handle service not running] ************************************************************
changed: [remote_server]

Conclusion

In this guide, we covered how to use the Ansible script module to execute shell scripts on remote servers. We explored basic execution, passing arguments. By leveraging this module, you can automate the execution of complex scripts across multiple servers.

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