Templates¶

A template is a YAML file under templates/ that declares a list of parametrised actions. A flowgroup invokes it with use_template: and supplies template_parameters:; LHP renders the {{ param }} placeholders with those values and expands the template into the flowgroup’s actions.

name: <template_name>
version: "1.0"
presets: []
parameters:
  - name: <param_name>
    required: <bool>
    default: <value>
actions:
  - name: "<action_{{ param_name }}>"
    type: <load|transform|write|test>
    ...

Template file fields¶

Top-level fields of a template file. Only name is required; every other field has a default.

Field	Type	Required	Default	Description
`name`	string	Yes	—	Template identifier, surfaced in validation errors.
`version`	string	No	`"1.0"`	Version tag for change tracking.
`description`	string	No	—	Human-readable summary of the template.
`presets`	list[string]	No	`[]`	Preset names applied to the actions this template generates.
`parameters`	list[mapping]	No	`[]`	Parameter declarations (entry schema below).
`actions`	list[mapping]	No	`[]`	Action patterns carrying `{{ param }}` placeholders. Same schema as flowgroup actions.

Parameter fields¶

Keys of a single entry in the parameters: list. The engine reads only name, required, and default.

Key	Type	Required	Default	Description
`name`	string	Yes	—	Parameter name. Referenced as `{{ name }}` in the template body and supplied by key under `template_parameters:`.
`required`	bool	No	`false`	When `true`, the invoking flowgroup must supply this parameter or generation fails.
`default`	any	No	—	Value used when the flowgroup omits the parameter.
`description`	string	No	—	Human-readable note. Not read by the engine.

Invoke from a flowgroup¶

A flowgroup expands a template through these two fields.

Field	Type	Required	Default	Description
`use_template`	string	No	—	File name (stem, without `.yaml`) of a template under `templates/` to expand into this flowgroup.
`template_parameters`	mapping	No	—	Values supplied to the template’s parameters, keyed by parameter name. Merged over declared defaults.

name: csv_to_bronze
version: "1.0"
parameters:
  - name: table_name
    required: true
  - name: file_format
    default: csv
actions:
  - name: "load_{{ table_name }}"
    type: load
    readMode: stream
    source:
      type: cloudfiles
      path: "${landing_volume}/{{ table_name }}/*.{{ file_format }}"
      format: "{{ file_format }}"
    target: "v_{{ table_name }}_raw"

pipeline: bronze
flowgroup: customer_ingestion
use_template: csv_to_bronze
template_parameters:
  table_name: customer
  file_format: csv