Ansible Level 01 – Day 05: Create Files on App Servers using Ansible

This document explains how to automate the creation of a file across multiple application servers while assigning different ownership based on the host. The automation relies on Ansible inventory variables so that a single playbook can dynamically apply the correct configuration to each system.

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Objective

Create a file on all application servers with the following properties:

• File Path: /tmp/webdata.txt
• Permissions: 0744

• Owner Requirements:

• stapp01 → tony

• stapp02 → steve
• stapp03 → banner

File locations:

• Inventory: ~/playbook/inventory
• Playbook: ~/playbook/playbook.yml

Execution command:

ansible-playbook -i inventory playbook.yml

The command must run successfully without requiring additional authentication flags.

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Automation Design

The automation is implemented using two components:

1. Inventory – defines the servers and their connection parameters
2. Playbook – defines the file creation task

The inventory stores the login user for each server. The playbook then references that variable to dynamically set the correct ownership.

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Step 1: Create the Inventory File

Create the working directory and inventory file.

mkdir -p ~/playbook
cd ~/playbook
vi inventory

Insert the following configuration:

[app]
stapp01 ansible_host=stapp01 ansible_user=tony ansible_ssh_pass=Ir0nM@n
stapp02 ansible_host=stapp02 ansible_user=steve ansible_ssh_pass=Am3ric@
stapp03 ansible_host=stapp03 ansible_user=banner ansible_ssh_pass=BigGr33n

[all:vars]
ansible_ssh_common_args='-o StrictHostKeyChecking=no'

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Explanation of Inventory Structure

[app]

Defines a host group containing all application servers.

Each host entry contains connection parameters required for SSH authentication.

ansible_host

The hostname or IP used for SSH connectivity.

ansible_user

Defines the remote login account for that server.

ansible_ssh_pass

Password used for SSH authentication.

[all:vars]

Defines variables applied to every host in the inventory.

ansible_ssh_common_args='-o StrictHostKeyChecking=no'

Prevents SSH from asking for manual host fingerprint confirmation.

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Step 2: Create the Playbook

Create the playbook file.

vi playbook.yml

Insert the following configuration.

---
- name: Create files on application servers
  hosts: all
  become: yes

  tasks:

    - name: Create /tmp/webdata.txt with required permissions
      file:
        path: /tmp/webdata.txt
        state: touch
        mode: '0744'
        owner: "{{ ansible_user }}"
        group: "{{ ansible_user }}"

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Explanation of the Playbook

Target Hosts

hosts: all

The task runs on every host defined in the inventory.

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Privilege Escalation

become: yes

Changing file ownership requires root privileges. This directive allows Ansible to execute the task using sudo.

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File Module

The file module manages file attributes such as creation, permissions, and ownership.

state: touch

Creates the file if it does not exist.

mode: '0744'

Defines file permissions:

• Owner → read, write, execute
• Group → read only
• Others → read only

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Dynamic Ownership Assignment

owner: "{{ ansible_user }}"

The variable ansible_user comes from the inventory.

During execution Ansible replaces the variable with the appropriate value for each host.

Example substitutions:

• stapp01 → owner becomes tony
• stapp02 → owner becomes steve
• stapp03 → owner becomes banner

This technique avoids writing multiple host-specific tasks.

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Step 3: Execute the Playbook

Run the playbook using the required command.

ansible-playbook -i inventory playbook.yml

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Expected Execution Output

Example execution result:

PLAY [Create files on application servers]

TASK [Gathering Facts]
ok: [stapp01]
ok: [stapp02]
ok: [stapp03]

TASK [Create /tmp/webdata.txt with required permissions]
changed: [stapp01]
changed: [stapp02]
changed: [stapp03]

PLAY RECAP
stapp01 : ok=2 changed=1 unreachable=0 failed=0
stapp02 : ok=2 changed=1 unreachable=0 failed=0
stapp03 : ok=2 changed=1 unreachable=0 failed=0

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Optional Verification

Verify the file and its ownership on all servers using an ad‑hoc command.

ansible all -i inventory -m command -a "ls -l /tmp/webdata.txt"

Expected output will show the correct owner for each host.

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Internal Execution Flow

When the playbook runs, Ansible performs the following operations:

1. Reads the inventory
2. Connects to each server using SSH
3. Escalates privileges using sudo
4. Creates the file /tmp/webdata.txt
5. Applies the specified permissions and ownership

The dynamic variable ensures the correct owner is applied automatically for each server.

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Key Outcome

A single Ansible playbook successfully creates /tmp/webdata.txt on all application servers while assigning the correct owner and permissions based on the host executing the task.