Ansible nmcli Module — Configure Network Connections

Introduction

Configure Network Connections. This guide provides practical Ansible examples, configuration patterns, and best practices for implementing this in production environments.

Overview

Effective use of Ansible nmcli Module requires understanding both the Ansible modules involved and the underlying technology. This guide covers both aspects with real-world examples.

Prerequisites

---
- name: Ensure prerequisites
  hosts: all
  become: true
  tasks:
    - name: Install required packages
      ansible.builtin.package:
        name:
          - python3
          - python3-pip
        state: present

Basic Implementation

---
- name: Configure Network Connections
  hosts: all
  become: true
  vars:
    app_name: myapp
    environment: production

  tasks:
    - name: Validate environment
      ansible.builtin.assert:
        that:
          - environment in ['development', 'staging', 'production']
        fail_msg: "Invalid environment: {{ environment }}"

    - name: Create directory structure
      ansible.builtin.file:
        path: "{{ item }}"
        state: directory
        mode: '0755'
      loop:
        - /opt/{{ app_name }}
        - /opt/{{ app_name }}/config
        - /opt/{{ app_name }}/data
        - /opt/{{ app_name }}/logs

    - name: Deploy configuration
      ansible.builtin.template:
        src: "config.j2"
        dest: "/opt/{{ app_name }}/config/main.yml"
        mode: '0644'
        validate: 'python3 -c "import yaml; yaml.safe_load(open(\"%s\"))"'
      notify: Restart application

Advanced Configuration

    - name: Configure with environment-specific values
      ansible.builtin.template:
        src: "{{ environment }}-config.j2"
        dest: "/opt/{{ app_name }}/config/env.yml"
        mode: '0644'
      vars:
        debug_mode: "{{ environment != 'production' }}"
        log_level: "{{ 'info' if environment == 'production' else 'debug' }}"

    - name: Set up monitoring
      ansible.builtin.template:
        src: monitoring.j2
        dest: "/opt/{{ app_name }}/config/monitoring.yml"
      when: monitoring_enabled | default(true)

Role Structure

roles/nmcli-module/
├── defaults/
│   └── main.yml          # Default variables
├── handlers/
│   └── main.yml          # Service restart handlers
├── meta/
│   └── main.yml          # Role metadata and dependencies
├── tasks/
│   ├── main.yml          # Main task entry point
│   ├── install.yml       # Installation tasks
│   ├── configure.yml     # Configuration tasks
│   └── verify.yml        # Verification tasks
├── templates/
│   └── config.j2         # Jinja2 templates
├── tests/
│   └── test.yml          # Test playbook
└── vars/
    └── main.yml          # Role-specific variables

Error Handling

    - name: Deploy with rollback
      block:
        - name: Back up current configuration
          ansible.builtin.copy:
            src: "/opt/{{ app_name }}/config/"
            dest: "/opt/{{ app_name }}/config.bak/"
            remote_src: true

        - name: Apply new configuration
          ansible.builtin.template:
            src: config.j2
            dest: "/opt/{{ app_name }}/config/main.yml"

        - name: Verify new configuration
          ansible.builtin.command:
            cmd: "/opt/{{ app_name }}/bin/validate-config"
          changed_when: false

      rescue:
        - name: Rollback on failure
          ansible.builtin.copy:
            src: "/opt/{{ app_name }}/config.bak/"
            dest: "/opt/{{ app_name }}/config/"
            remote_src: true

        - name: Notify about failure
          ansible.builtin.debug:
            msg: "Deployment failed on {{ inventory_hostname }} — rolled back"

      always:
        - name: Clean up backup
          ansible.builtin.file:
            path: "/opt/{{ app_name }}/config.bak"
            state: absent

Handlers

  handlers:
    - name: Restart application
      ansible.builtin.systemd:
        name: "{{ app_name }}"
        state: restarted
        daemon_reload: true

    - name: Reload configuration
      ansible.builtin.systemd:
        name: "{{ app_name }}"
        state: reloaded

Testing

# Dry run
ansible-playbook site.yml --check --diff

# Limit to specific hosts
ansible-playbook site.yml --limit webservers

# Run specific tags
ansible-playbook site.yml --tags configure

# Verbose output for debugging
ansible-playbook site.yml -vvv

Troubleshooting

Issue	Solution
Variable undefined	Check `defaults/main.yml` and variable precedence
Template error	Validate Jinja2 syntax with `ansible-playbook --syntax-check`
Permission denied	Verify `become: true` and sudo configuration
Handler not triggered	Ensure task reports `changed` status
Idempotency issues	Test with `--check` to verify no unexpected changes

Best Practices

Use roles for reusable, modular automation
Parameterize everything — avoid hardcoded values
Test in staging first — never deploy directly to production
Use check mode for validation: --check --diff
Document your playbooks with comments and README files
Version control all playbooks and roles in Git
Use tags for selective task execution
Implement error handling with block/rescue/always

Conclusion

This guide covered the practical implementation of Ansible nmcli Module. Start with the basic examples, customize for your environment, and gradually add error handling, monitoring, and CI/CD integration as your automation matures.