📋 Node Attributes

Node attributes provide host-specific data to your recipes. They allow you to write generic recipes that adapt to different environments.

📥 Loading Attributes

📄 From JSON

itamae local --node-json node.json recipe.rb

{
  "hostname": "web01",
  "app": {
    "port": 3000,
    "workers": 4
  }
}

📝 From YAML

itamae local --node-yaml node.yml recipe.rb

hostname: web01
app:
  port: 3000
  workers: 4

📚 Multiple files

Load and deep-merge multiple attribute files. Later files take precedence:

itamae local -j base.json -j web.json -y overrides.yml recipe.rb

🔑 Accessing Attributes

Use the node object in recipes:

execute "hostname #{node[:hostname]}"

template '/etc/app.conf' do
  variables(
    port: node[:app][:port],
    workers: node[:app][:workers]
  )
end

In templates, access node directly:

hostname = <%= node[:hostname] %>
port = <%= node[:app][:port] %>

🔀 Flexible access

Node attributes use Hashie::Mash, so you can access them with symbols, strings, or method syntax:

node[:app][:port]      # symbol keys
node['app']['port']    # string keys
node.app.port          # method syntax

✅ Validation

Validate attributes before recipe execution to catch configuration errors early:

node.validate! do
  {
    nginx: {
      user: string,
      worker_processes: optional(integer),
      sites: array_of({
        server_name: string,
        root: string,
        allowed_ips: array_of(string),
      }),
    },
  }
end

Validation types:

• string – must be a String
• integer – must be an Integer
• boolean – must be true or false
• optional(type) – may be nil
• array_of(type) – array where each element matches type

When validation fails, provisioning halts with an error message.

📊 Host Inventory

Itamae automatically collects system facts from the target host. These are merged into node attributes:

node[:platform]           # "ubuntu", "centos", etc.
node[:platform_version]   # "22.04", "9", etc.

Host inventory data is lazy-loaded when first accessed.

⚠️ Ohai Integration (Deprecated)

Load comprehensive system data via Ohai:

itamae local --ohai recipe.rb

If Ohai is not found on the target host, Itamae will install it. This option is deprecated – prefer host inventory or explicit node JSON/YAML.