Creating Reusable Roles

Creating Reusable Roles

Role Development Workflow

Planning Phase

• Define role purpose
• Identify dependencies
• Plan directory structure
• Determine variables

Implementation Steps

1. Initialize role structure

   ansible-galaxy init role_name
   

2. Define metadata
3. Create tasks
4. Set default variables
5. Add handlers if needed

Role Development Best Practices

Modularity

• Single responsibility principle
• Clear dependencies
• Minimal coupling
• Maximum cohesion

Naming Conventions

# Good Examples
roles/
  webserver/       # Clear purpose
  database_mysql/  # Specific implementation
  security_base/   # Functional area

# Bad Examples
roles/
  role1/          # Unclear purpose
  stuff/          # Too generic
  misc/           # Not descriptive

Variable Management

# defaults/main.yml
---
app_port: 8080
app_user: "webapp"
app_group: ""

app_config_template: "app.conf.j2"
app_config_path: "/etc/app/config.conf"

app_features:
  logging: true
  monitoring: false
  backups: true

Testing and Validation

Test Structure

# tests/inventory
[local]
localhost ansible_connection=local

# tests/test.yml
---
- hosts: local
  roles:
    - role: your_role_name
      vars:
        app_port: 9000

Testing Methods

1. Syntax Check

   ansible-playbook --syntax-check tests/test.yml
   

2. Dry Run

   ansible-playbook -C tests/test.yml
   

3. Full Test

   ansible-playbook tests/test.yml
   

Molecule Testing

# molecule/default/molecule.yml
---
dependency:
  name: galaxy
driver:
  name: docker
platforms:
  - name: instance
    image: ubuntu:latest
    pre_build_image: true
provisioner:
  name: ansible
verifier:
  name: ansible

Documentation Standards

README Structure

# Role Name

Brief description of the role's purpose

## Requirements

List prerequisites and dependencies

## Role Variables

Document all variables and their defaults

## Dependencies

List required roles

## Example Playbook

Show usage examples

## License

Specify the license

## Author Information

Provide contact details

Variable Documentation

# defaults/main.yml
---
# Port number for the application
# Default: 8080
app_port: 8080

# User to run the application
# Default: webapp
app_user: webapp

# Feature flags for optional components
# Default: see below
app_features:
  logging: true    # Enable application logging
  monitoring: false # Enable monitoring integration
  backups: true    # Enable automated backups

Version Control

Git Structure

role_name/
  .git/
  .gitignore
  molecule/
  tasks/
  templates/
  tests/
  README.md
  meta/main.yml

.gitignore Example

*.retry
*.pyc
__pycache__/
.molecule/
.cache/

Practical Exercise

Creating a Web Server Role

1. Initialize role structure
2. Implement basic tasks
3. Add configuration templates
4. Write tests
5. Document the role

Role Testing Process

1. Syntax validation
2. Local testing
3. Integration testing
4. Documentation review

Key Takeaways

• Plan before implementing
• Test thoroughly
• Document comprehensively
• Follow best practices

Additional Resources

• Ansible Galaxy Guide
• Molecule Documentation
• Ansible Testing Strategies