Ansible notes

**Ansible Notes for SRE / AWS DevOps Interview Preparation**

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### 1. **Introduction to Ansible**

* Open-source tool for automation: provisioning, configuration management, application deployment.
* Used for managing servers, installing software, updates, orchestration.
* Written in Python; uses **YAML** for playbooks.
* **Agentless**: communicates via SSH; no client agent needed.
* GUI: **Ansible Tower** (drag and drop interface).

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### 2. **Key Features**

* **Agentless** architecture.
* **Simple syntax** using YAML (human-readable, key-value format).
* **Extensible and modular** via custom roles.
* Efficient for large environments.

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### 3. **Playbooks**

* Written in YAML, used to define automation tasks.
* Components:

  * **Target Section**: hosts definition.
  * **Variable Section**: variable definitions.
  * **Task Section**: modules used to execute actions.
* Structure includes `vars`, `tasks`, `handlers`, `files`, `templates`, and `roles`.

**Example Modules Used in Playbooks:**

* `yum`, `apt`: Package installation
* `copy`, `template`: File and template handling
* `service`: Service management
* `debug`: Debugging output

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### 4. **Variable Handling**

* Use `--extra-vars` to pass dynamic variables:

  * Single: `ansible-playbook file.yml --extra-vars "abc=git"`
  * Multiple: `ansible-playbook file.yml --extra-vars "abc=git def=maven"`

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### 5. **Common Use Cases / Tasks**

* Install packages (e.g., Git, Apache)
* Start/stop/restart services
* Create users and groups
* Manage files and directories
* Configure permissions
* Deploy websites
* Pull code from GitHub (with token if private repo)

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### 6. **Handlers & Conditions**

* **Handlers**: Execute only if notified (e.g., restart service if config changes).
* **Conditions**: Run tasks based on `when` clauses (conditional logic).

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### 7. **Tags in Playbooks**

* Execute specific parts of playbook:

  * Run specific: `ansible-playbook file.yml --tags tagname`
  * Skip tags: `ansible-playbook file.yml --skip-tags tagname`

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### 8. **Roles**

* Used to organize complex playbooks into reusable components.
* Directory structure includes: `defaults`, `files`, `handlers`, `meta`, `tasks`, `templates`, `vars`.
* Created with `ansible-galaxy init rolename`

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### 9. **Ad-Hoc Commands**

* Quick one-time tasks from CLI without playbooks.

  * Ex: `ansible all -m yum -a "name=httpd state=present"`

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### 10. **Modules Overview**

* **Core building blocks** of Ansible.
* Types include: `yum`, `apt`, `service`, `file`, `copy`, `user`, `command`, `debug`, etc.

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### 11. **Ansible Galaxy**

* Community repository for roles/playbooks.
* Common commands:

  * Search: `ansible-galaxy search role`
  * Install: `ansible-galaxy install author.rolename`

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### 12. **Ansible Vault**

* Secure sensitive data like passwords and tokens.
* Commands:

  * `ansible-vault create vault.yml`
  * `ansible-vault edit/view/encrypt/decrypt vault.yml`
  * Use `--ask-vault-pass` or `--vault-password-file` during execution.

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### 13. **Interview Tips**

* Emphasize idempotency.
* Mention role-based modularization.
* Describe Vault use for secrets.
* Explain handlers for service restart.
* Reference ad-hoc use for real-time on-call troubleshooting.
* Discuss dynamic inventory or EC2 provisioning.



Here’s a set of sample Ansible playbooks you can add to your practice or portfolio, based on your notes and common SRE/AWS DevOps use cases:

📦 1. Install Apache Web Server
yaml
Copy
Edit
- name: Install Apache on Web Servers
  hosts: webservers
  become: yes
  tasks:
    - name: Install Apache
      yum:
        name: httpd
        state: present

    - name: Start Apache
      service:
        name: httpd
        state: started
        enabled: yes
📁 2. Create a File with Content
yaml
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Edit
- name: Create and write to a file
  hosts: localhost
  tasks:
    - name: Create file with content
      copy:
        content: "Hello from Ansible!"
        dest: /tmp/hello.txt
👥 3. Add Multiple Users
yaml
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- name: Add multiple users
  hosts: all
  become: yes
  vars:
    users:
      - alice
      - bob
  tasks:
    - name: Create users
      user:
        name: "{{ item }}"
        state: present
      loop: "{{ users }}"
🔁 4. Restart Service with Handlers
yaml
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- name: Update config and restart service
  hosts: all
  become: yes
  tasks:
    - name: Update config file
      copy:
        src: myconfig.conf
        dest: /etc/myapp/config.conf
      notify: Restart myapp

  handlers:
    - name: Restart myapp
      service:
        name: myapp
        state: restarted
🔄 5. Conditional Task Execution
yaml
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- name: Run only if variable is true
  hosts: localhost
  vars:
    install_git: true
  tasks:
    - name: Install Git if condition is met
      yum:
        name: git
        state: present
      when: install_git
🌐 6. Deploy Website from GitHub
yaml
Copy
Edit
- name: Deploy static website
  hosts: webservers
  become: yes
  tasks:
    - name: Clone website repo
      git:
        repo: https://token@github.com/youruser/yourrepo.git
        dest: /var/www/html