Advanced YAML Features: Anchors, Aliases, and Merging

Intermediate

🧠 Advanced YAML Features: Anchors, Aliases & Merge Keys

Advanced YAML features like anchors (&), aliases (*), and merge keys (<<) enable efficient reuse and composition of data structures.

🔗 Anchors & Aliases

Label a node with an anchor and refer to it with an alias.

default_settings: &defaults
  retries: 5
  timeout: 60

server:
  <<: *defaults
  host: example.com
  port: 8080

✅ *defaults pulls in the values defined in &defaults, merging them into server.

🔁 Merge Keys (<<)

Merge multiple mappings into one and override specific values:

base: &base
  user: admin
  permissions:
    read: true
    write: false

override:
  <<: *base
  permissions:
    write: true

✅ override inherits from base, but modifies the write permission.

💡 Best Practices

  • 🧼 Use anchors sparingly for clarity
  • 🔤 Maintain consistent naming conventions
  • 📦 Combine with inline mappings for compactness

🚀 Use Cases

  • 🛠️ Configuration templates
  • ⚙️ Sharing common settings across resources
  • 📉 Reducing duplication in large YAML files

These features promote reusability, maintainability, and clarity in YAML structures.