08 - Tags

Learn how to use tags to selectively run parts of your configuration.

What You'll Learn

• Adding tags to steps
• Filtering execution with --tags flag
• Organizing workflows with tags
• Combining tags with conditionals

Quick Start

cd examples/08-tags

# Run all steps (no tag filter)
mooncake run --config config.yml

# Run only development steps
mooncake run --config config.yml --tags dev

# Run only production steps
mooncake run --config config.yml --tags prod

# Run test-related steps
mooncake run --config config.yml --tags test

# Run multiple tag categories
mooncake run --config config.yml --tags dev,test

What It Does

Demonstrates different tagged workflows: - Development setup - Production deployment - Testing - Security audits - Staging deployment

Key Concepts

Adding Tags

- name: Install dev tools
  shell: echo "Installing tools"
  tags:
    - dev
    - tools

Tag Filtering Behavior

No tags specified: - All steps run (including untagged steps)

Tags specified (--tags dev): - Only steps with matching tags run - Untagged steps are skipped

Multiple tags (--tags dev,prod): - Steps run if they have ANY of the specified tags - OR logic: matches dev OR prod

Tag Organization Strategies

By Environment:

tags: [dev, staging, prod]

By Phase:

tags: [setup, deploy, test, cleanup]

By Component:

tags: [database, webserver, cache]

By Role:

tags: [install, configure, security]

Multiple Tags Per Step

Steps can have multiple tags:

- name: Security audit
  shell: run-security-scan
  tags:
    - test
    - prod
    - security

This runs with: - --tags test ✓ - --tags prod ✓ - --tags security ✓ - --tags dev ✗

Real-World Examples

Development Workflow

# Install dev tools only
mooncake run --config config.yml --tags dev,tools

# Run tests
mooncake run --config config.yml --tags test

Production Deployment

# Deploy to production
mooncake run --config config.yml --tags prod,deploy

# Run security checks
mooncake run --config config.yml --tags security,prod

Staging Environment

# Deploy to staging
mooncake run --config config.yml --tags staging,deploy

Combining Tags and Conditionals

- name: Install Linux dev tools
  shell: apt install build-essential
  become: true
  when: os == "linux"
  tags:
    - dev
    - tools

Both must match: 1. Condition must be true (os == "linux") 2. Tag must match (if --tags specified)

Testing Different Tag Filters

# Preview what runs with dev tag
mooncake run --config config.yml --tags dev --dry-run

# Run dev and test steps
mooncake run --config config.yml --tags dev,test

# Run only setup steps
mooncake run --config config.yml --tags setup

Best Practices

1. Use consistent naming - Pick a scheme (env, phase, role) and stick to it
2. Multiple tags per step - Makes filtering more flexible
3. Document your tags - In README or comments
4. Combine with conditionals - For environment + OS filtering

Next Steps

Continue to 09-sudo to learn about privilege escalation.