🧪 Testing, CI/CD & Infrastructure as Code

# .gitlab-ci.yml Example
stages:
  - validate
  - test
  - deploy

validate_syntax:
  stage: validate
  script:
    - yamllint playbooks/
    - ansible-lint playbooks/
    - python -m py_compile scripts/*.py

test_network:
  stage: test
  script:
    - pytest tests/ -v
    - pyats run job test_job.py
  artifacts:
    reports:
      junit: test-results.xml

deploy_to_staging:
  stage: deploy
  script:
    - ansible-playbook -i inventory/staging playbooks/configure_network.yml
  environment:
    name: staging
  only:
    - develop

deploy_to_production:
  stage: deploy
  script:
    - ansible-playbook -i inventory/production playbooks/configure_network.yml
  environment:
    name: production
  only:
    - main
  when: manual

# GitHub Actions Workflow (.github/workflows/network-deploy.yml)
name: Network Configuration CI/CD

on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]

jobs:
  validate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      
      - name: Set up Python
        uses: actions/setup-python@v2
        with:
          python-version: '3.9'
      
      - name: Install dependencies
        run: |
          pip install ansible ansible-lint yamllint pyats genie
      
      - name: Lint YAML files
        run: yamllint configs/
      
      - name: Lint Ansible playbooks
        run: ansible-lint playbooks/

  test:
    needs: validate
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      
      - name: Run pyATS tests
        run: |
          pyats run job tests/network_test_job.py --testbed testbed.yaml

  deploy:
    needs: test
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    environment: production
    steps:
      - uses: actions/checkout@v2
      
      - name: Deploy to production
        run: |
          ansible-playbook -i inventory/production playbooks/deploy.yml

# DECLARATIVE (Terraform)
# Define desired state
resource "cisco_interface" "gig0_1" {
  name        = "GigabitEthernet0/1"
  description = "WAN Interface"
  ip_address  = "10.1.1.1"
  subnet_mask = "255.255.255.0"
  enabled     = true
}

# Terraform figures out HOW to achieve this state

# IMPERATIVE (Ansible/Python)
# Define steps to execute
- name: Configure interface
  cisco.ios.ios_config:
    lines:
      - description WAN Interface
      - ip address 10.1.1.1 255.255.255.0
      - no shutdown
    parents: interface GigabitEthernet0/1

# You specify WHAT to do step by step

# Directory Structure
network-iac/
├── inventory/
│   ├── production/
│   │   └── hosts.yml
│   └── staging/
│       └── hosts.yml
├── group_vars/
│   ├── routers.yml
│   └── switches.yml
├── roles/
│   ├── interfaces/
│   ├── routing/
│   └── security/
└── playbooks/
    └── deploy_network.yml

# group_vars/routers.yml
---
ntp_servers:
  - 10.1.1.1
  - 10.1.1.2

dns_servers:
  - 8.8.8.8
  - 8.8.4.4

logging_server: 10.1.1.100

# roles/interfaces/tasks/main.yml
---
- name: Configure interfaces
  cisco.ios.ios_interfaces:
    config:
      - name: "{{ item.name }}"
        description: "{{ item.description }}"
        enabled: "{{ item.enabled | default(true) }}"
  loop: "{{ interfaces }}"

- name: Configure IP addresses
  cisco.ios.ios_l3_interfaces:
    config:
      - name: "{{ item.name }}"
        ipv4:
          - address: "{{ item.ip }}"
  loop: "{{ interfaces }}"
  when: item.ip is defined

# playbooks/deploy_network.yml
---
- name: Deploy Network Configuration
  hosts: routers
  gather_facts: no
  
  roles:
    - interfaces
    - routing
    - security
  
  tasks:
    - name: Save configuration
      cisco.ios.ios_config:
        save_when: always