Managing Configuration

Configuration Management

Purpose

This skill provides guidance for automating server and application configuration using Ansible and related tools. It covers playbook creation, role structure, inventory management (static and dynamic), secret management, testing patterns, and idempotency best practices to ensure safe, repeatable configuration deployments.

When to Use This Skill

Invoke this skill when:

• Creating Ansible playbooks to configure servers or deploy applications
• Structuring reusable Ansible roles with proper directory layout
• Managing inventories (static files or dynamic cloud-based)
• Securing secrets with ansible-vault or HashiCorp Vault integration
• Testing roles with Molecule before production deployment
• Ensuring idempotent playbooks that safely run multiple times
• Migrating from Chef or Puppet to Ansible
• Implementing GitOps workflows for configuration as code
• Debugging playbook failures or handler issues

Quick Start

Basic Playbook Example

yamlCopy code
---
# site.yml
- name: Configure web servers
  hosts: webservers
  become: yes

  tasks:
    - name: Ensure nginx is installed
      apt:
        name: nginx
        state: present
      notify: Restart nginx

    - name: Start nginx service
      service:
        name: nginx
        state: started
        enabled: yes

  handlers:
    - name: Restart nginx
      service:
        name: nginx
        state: restarted

Run with:

bashCopy code
ansible-playbook -i inventory/production site.yml

Core Concepts

1. Idempotency

Run playbooks multiple times without unintended side effects. Use state-based modules (present, started, latest) instead of imperative commands.

Idempotent (good):

yamlCopy code
- name: Ensure package installed
  apt:
    name: nginx
    state: present

Not idempotent (avoid):

yamlCopy code
- name: Install package
  command: apt-get install -y nginx

See references/idempotency-guide.md for detailed patterns.

2. Inventory Management

Static Inventory: INI or YAML files for stable environments. Dynamic Inventory: Scripts or plugins for cloud environments (AWS, Azure, GCP).

Example static inventory (INI):

iniCopy code
[webservers]
web1.example.com ansible_host=10.0.1.10
web2.example.com ansible_host=10.0.1.11

[webservers:vars]
nginx_worker_processes=4

See references/inventory-management.md for dynamic inventory setup.

3. Roles vs Playbooks

Playbooks: Orchestrate multiple tasks and roles for specific deployments. Roles: Reusable, self-contained configuration units with standardized directory structure.

Standard role structure:

Copy code
roles/nginx/
├── defaults/     # Default variables
├── tasks/        # Task files
├── handlers/     # Change handlers
├── templates/    # Jinja2 templates
├── files/        # Static files
└── meta/         # Dependencies

See references/role-structure.md for complete role patterns.

4. Secret Management

ansible-vault: Built-in encryption for sensitive data. HashiCorp Vault: Enterprise-grade secrets management with dynamic credentials.

Encrypt secrets:

bashCopy code
ansible-vault create group_vars/all/vault.yml
ansible-playbook site.yml --ask-vault-pass

See references/secrets-management.md for Vault integration.

Common Workflows

Workflow 1: Create New Playbook

Step 1: Define inventory

iniCopy code
# inventory/production
[webservers]
web1.example.com
web2.example.com

Step 2: Create playbook structure

yamlCopy code
---
- name: Configure application
  hosts: webservers
  become: yes

  pre_tasks:
    - name: Update package cache
      apt:
        update_cache: yes

  roles:
    - common
    - application

  post_tasks:
    - name: Verify service
      uri:
        url: http://localhost:8080/health
        status_code: 200

Step 3: Test with check mode

bashCopy code
ansible-playbook -i inventory/production site.yml --check --diff

Step 4: Execute playbook

bashCopy code
ansible-playbook -i inventory/production site.yml

See references/playbook-patterns.md for advanced patterns.

Workflow 2: Create and Test Role

Step 1: Initialize role structure

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ansible-galaxy init roles/myapp

Step 2: Define tasks

yamlCopy code
# roles/myapp/tasks/main.yml
---
- name: Install application dependencies
  apt:
    name: "{{ item }}"
    state: present
  loop: "{{ myapp_dependencies }}"

- name: Deploy application
  template:
    src: app.conf.j2
    dest: /etc/myapp/app.conf
  notify: Restart myapp

Step 3: Add handler

yamlCopy code
# roles/myapp/handlers/main.yml
---
- name: Restart myapp
  service:
    name: myapp
    state: restarted

Step 4: Initialize Molecule testing

bashCopy code
cd roles/myapp
molecule init scenario default --driver-name docker

Step 5: Run tests

bashCopy code
molecule test

See references/testing-guide.md for comprehensive testing patterns.

Workflow 3: Set Up Dynamic Inventory (AWS)

Step 1: Install AWS collection

bashCopy code
ansible-galaxy collection install amazon.aws

Step 2: Configure dynamic inventory

yamlCopy code
# inventory/aws_ec2.yml
plugin: aws_ec2
regions:
  - us-east-1
filters:
  tag:Environment: production
  instance-state-name: running
keyed_groups:
  - key: tags.Role
    prefix: role
hostnames:
  - tag:Name
compose:
  ansible_host: private_ip_address

Step 3: Verify inventory

bashCopy code
ansible-inventory -i inventory/aws_ec2.yml --list

Step 4: Run playbook

bashCopy code
ansible-playbook -i inventory/aws_ec2.yml site.yml

See references/inventory-management.md for multi-cloud patterns.

Workflow 4: Secure Secrets with ansible-vault

Step 1: Create encrypted vault file

bashCopy code
ansible-vault create group_vars/all/vault.yml

Step 2: Add secrets

yamlCopy code
# group_vars/all/vault.yml (encrypted)
vault_db_password: "SuperSecretPassword"
vault_api_key: "sk-1234567890"

Step 3: Reference in variables

yamlCopy code
# group_vars/all/vars.yml (unencrypted)
db_password: "{{ vault_db_password }}"
api_key: "{{ vault_api_key }}"

Step 4: Use in playbook

yamlCopy code
- name: Configure database
  template:
    src: db.conf.j2
    dest: /etc/app/db.conf
  vars:
    database_password: "{{ db_password }}"

Step 5: Run with vault password

bashCopy code
ansible-playbook site.yml --vault-password-file ~/.vault_pass

See references/secrets-management.md for HashiCorp Vault integration.

Tool Selection

When to Use Ansible

• Configuring servers/VMs after provisioning
• Deploying applications to existing infrastructure
• Managing OS-level settings (users, packages, services)
• Orchestrating multi-step workflows across hosts
• Cloud-native environments (agentless SSH/WinRM)
• Teams new to configuration management (easiest learning curve)

When to Use Alternatives

Infrastructure-as-Code (Terraform): Creating cloud infrastructure resources. Kubernetes: Container orchestration and configuration. Chef/Puppet: Existing deployments with high migration costs.

Ansible vs IaC Integration

Best practice: Terraform provisions, Ansible configures.

Workflow:

1. Terraform creates AWS EC2 instances, security groups, load balancers
2. Terraform outputs instance IPs to Ansible inventory
3. Ansible configures OS, installs packages, deploys applications
4. Ansible sets up monitoring, backups, operational tasks

See references/decision-framework.md for detailed decision trees.

Testing and Quality

Pre-Deployment Validation

Step 1: Lint playbooks

bashCopy code
ansible-lint playbooks/

Step 2: Check mode (dry run)

bashCopy code
ansible-playbook site.yml --check --diff

Step 3: Test roles with Molecule

bashCopy code
cd roles/myapp
molecule test

Step 4: Verify idempotence

bashCopy code
molecule idempotence

Configuration Files

.ansible-lint:

yamlCopy code
---
exclude_paths:
  - molecule/
  - venv/
skip_list:
  - name[casing]
warn_list:
  - experimental

molecule.yml:

yamlCopy code
---
driver:
  name: docker
platforms:
  - name: instance
    image: ubuntu:22.04
    pre_build_image: true
provisioner:
  name: ansible
verifier:
  name: ansible

See references/testing-guide.md for complete testing strategies.

Troubleshooting

Common Issues

Connection failures:

• Verify SSH access: ansible all -i inventory -m ping
• Check SSH keys: ssh -vvv user@host
• Test with password: ansible-playbook site.yml --ask-pass

Handler not firing:

• Handlers only run on change (check task changed status)
• Handlers run at end of playbook (use meta: flush_handlers to force earlier)
• Handler names must match exactly

Variable not defined:

• Check variable precedence (command-line > playbook > inventory > defaults)
• Use debug module: - debug: var=myvar
• Verify variable files are loaded: ansible-playbook site.yml -v

Idempotency violations:

• Run playbook twice, compare output
• Check for changed on every run
• Use state-based modules instead of command/shell

See references/troubleshooting.md for comprehensive debugging guide.

Integration with Other Skills

infrastructure-as-code:

• Terraform provisions infrastructure
• Ansible configures post-provisioning
• Terraform outputs feed Ansible inventory

kubernetes-operations:

• Ansible deploys K8s clusters (kubespray)
• Kubernetes handles container orchestration
• Ansible manages node-level configuration

building-ci-pipelines:

• CI/CD runs ansible-lint for quality checks
• Molecule tests execute in pipeline
• Deployment stage runs playbooks

secret-management:

• ansible-vault for simple use cases
• HashiCorp Vault for enterprise secrets
• Dynamic credentials via Vault lookups

security-hardening:

• Ansible applies CIS benchmarks
• Security roles enforce compliance
• Molecule verifies hardening effectiveness

testing-strategies:

• Molecule for role testing
• Testinfra for verification
• Integration test suites

Reference Documentation

• references/playbook-patterns.md - Playbook structure, handlers, tags, variables
• references/role-structure.md - Role directory layout, best practices, collections
• references/inventory-management.md - Static, dynamic, and hybrid inventory patterns
• references/secrets-management.md - ansible-vault and HashiCorp Vault integration
• references/testing-guide.md - Molecule, ansible-lint, check mode, verification
• references/idempotency-guide.md - Ensuring safe, repeatable executions
• references/decision-framework.md - Tool selection and workflow design
• references/chef-puppet-migration.md - Migrating from legacy tools to Ansible
• references/troubleshooting.md - Common issues and debugging techniques

Example Code

• examples/playbooks/ - Complete playbook examples
• examples/roles/ - Production-ready role templates
• examples/inventory/ - Static and dynamic inventory configurations
• examples/molecule/ - Molecule test scenarios

Utility Scripts

• scripts/validate-playbook.py - Validate playbook syntax and structure
• scripts/generate-inventory.py - Generate inventory from cloud providers
• scripts/ansible-vault-helper.sh - Vault management utilities
• scripts/molecule-runner.sh - Automated Molecule test execution