Convention-Based Creation (create_from)

Generating Resources from Property Values and Data Lists

The create_from directive inside a [[create_resource]] block provides two powerful convention-over-configuration patterns for resource creation.

• create_from = { property = "..." } — creates resources from the values of a property on the origin_resource
• create_from = { list = "..." } — creates resources by iterating over an abstract data list defined in the header

Both patterns make the iterated item available as {{ value }} inside templates.

Pattern 1: Creating from a Property Value

When a property contains a list (an array or a comma-separated string), create_from creates one resource for each item. The property name becomes the default resource type, and the property value becomes the default primary key (name). Both can be overridden.

data/assets/application.csv

name,service
zabbix,"monitoring, alerting"

data/models/application_services.toml

origin_resource = "application"

[[create_resource]]
create_from = { property = "service" }
relation_type = "PROVIDES"
name = "svc-{{ value | upper }}"
[create_resource.properties]
category = "Operations"

Result: Two service resources are created — svc-MONITORING and svc-ALERTING — each linked to the zabbix application via a PROVIDES relationship.

Type Resolution Priority

The resource type for items created by create_from is resolved in this order (highest priority first):

1. The as key inside the create_from block: create_from = { property = "service", as = "platform_service" }
2. The top-level resource_type directive
3. The property name itself (e.g., "service")

Deriving from a Related Node (property_origin and relation_origin)

Use property_origin to read the source property from a related node instead of the origin_resource. Use relation_origin to control where the new relationship starts from.

Goal: From a subscription, find its related application, read its service property, and create service resources linked back to the subscription (not the application).

origin_resource = "subscription"

[[create_resource]]
property_origin = "application"           # Read the property from the related application
create_from = { property = "service" }
relation_type = "USES"
relation_origin = "origin_resource"       # Start the new relation from the subscription

Pattern 2: Creating from a Data List

When used with list, create_from iterates over a variable defined in the file header. This is ideal for bootstrapping a graph from configuration data rather than from existing graph resources. No origin_resource is needed or available.

# data/models/providers.toml
# No origin_resource is defined.

provider_list = ["aws", "azure", "gcp"]

[[create_resource]]
create_from = { list = "provider_list", as = "provider" }
name = "cloud-{{ value }}"
[create_resource.properties]
short_name = "{{ value | upper }}"
category = "IaaS"

Result: Three provider resources are created: cloud-aws, cloud-azure, and cloud-gcp.

Comparison of Creation Patterns

For the full [[create_resource]] directive reference including copy_from, see [[create_resource]] Reference.