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Aisalkyn Aidarova
Aisalkyn Aidarova

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LAB: Deploy Nginx with Variables, Templates & Handlers

#automation #aws #devops #tutorial

🎯 Objective

  • Use common modules (apt, template, service)
  • Understand variables
  • See variable precedence in action
  • Use Jinja2 template
  • Trigger handler on config change
  • Observe idempotency

πŸ— Architecture

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Flow:

Mac (Control Node)
β†’ SSH
β†’ 2 Ubuntu EC2 Instances
β†’ Install & Configure Nginx

πŸ”Ή Step 1 – Launch 2 EC2 Instances

AMI: Ubuntu 22.04
Instance type: t2.micro
Security Group:

  • Port 22 (SSH)
  • Port 80 (HTTP)

πŸ”Ή Step 2 – Install Ansible (Control Node) 

brew install ansible
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Verify:

ansible --version
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πŸ”Ή Step 3 – Create Inventory

inventory.ini

[web]
node1 ansible_host=3.x.x.x
node2 ansible_host=18.x.x.x

[web:vars]
ansible_user=ubuntu
ansible_ssh_private_key_file=~/Downloads/key.pem
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Test:

ansible web -i inventory.ini -m ping
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πŸ”Ή Step 4 – Create Project Structure 

ansible-nginx-lab/
β”‚
β”œβ”€β”€ inventory.ini
β”œβ”€β”€ deploy.yml
β”œβ”€β”€ group_vars/
β”‚   └── web.yml
└── templates/
    └── nginx.conf.j2
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πŸ”Ή Step 5 – Variables (Group Level)

group_vars/web.yml

app_port: 80
server_name: jumptotech.local
welcome_message: "Welcome to JumpToTech DevOps Lab"
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πŸ”Ή Step 6 – Create Template (Jinja2)

templates/nginx.conf.j2

```server {
listen {{ app_port }};
server_name {{ server_name }};

location / {
    default_type text/plain;
    return 200 "{{ welcome_message }}\n";
}
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}




Students now see:
πŸ‘‰ Variables being injected dynamically.

---

# πŸ”Ή Step 7 – Create Playbook

`deploy.yml`



```yaml
- name: Deploy Nginx with Template
  hosts: web
  become: yes

  vars:
    server_name: override.local   # Playbook variable (higher precedence)

  tasks:

    - name: Install nginx
      apt:
        name: nginx
        state: present
        update_cache: yes

    - name: Deploy nginx config from template
      template:
        src: templates/nginx.conf.j2
        dest: /etc/nginx/sites-available/default
      notify: Restart nginx

    - name: Ensure nginx is running
      service:
        name: nginx
        state: started
        enabled: yes

  handlers:
    - name: Restart nginx
      service:
        name: nginx
        state: restarted
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πŸ”Ή Step 8 – Run Playbook 

ansible-playbook -i inventory.ini deploy.yml
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Open browser:

http://<EC2-IP>
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You should see:

Welcome to JumpToTech DevOps Lab
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πŸ”₯ What Students Just Learned

βœ… Modules

  • apt
  • template
  • service

βœ… Variables

  • group_vars
  • playbook vars

βœ… Variable Precedence

We defined:

In group_vars:

server_name: jumptotech.local
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In playbook:

vars:
  server_name: override.local
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Result?

Playbook variable wins.

To prove precedence:

Run with extra variable:

ansible-playbook -i inventory.ini deploy.yml -e "server_name=prod.local"
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Extra vars override everything.

Precedence (simplified):

lowest β†’ highest

  1. role defaults
  2. group_vars
  3. play vars
  4. extra vars (-e)

βœ… Template

Jinja2 variable rendering

βœ… Handler

Handler only runs if template changes.

Test it:

Run playbook again without changes:

You’ll see:

ok=3 changed=0
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Handler will NOT run.

Now change welcome_message in group_vars and rerun.

Handler triggers.

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