Example: Scaffold YAML Functions

Load a shared reference table once from a local file via !include, instead of hand-duplicating the same list of choices across fields or re-deriving the same lookup data in every file that needs it — plus pull in small dynamic values like an environment variable or the current git branch via !env and !git.branch, with no need to prompt the user for them.

Learn more in the Scaffold Command Documentation.

What You'll See

• A YQ-filtered !include shaping lib/licenses.yaml into real {label, value} options for a select field, so the choice list lives in one file instead of being typed into scaffold.yaml directly
• An unfiltered !include on a type: computed field landing the same file's raw structure at .Config.license_lookup, read from NOTICE.md via a plain lookup (index)
• !git.branch and !env on two more type: computed fields, each with a fallback default so generation still works outside a git repository or without the environment variable set
• lib/licenses.yaml — despite being declared in spec.files[] like any other file — never appearing in generated output, since it exists solely to be included

Try It

# List available scaffold templates
atmos scaffold list

# Generate with a valid license
atmos scaffold generate example ./my-project --set license=MIT

# The options: list is real, not just documentation -- an invalid value is rejected
atmos scaffold generate example ./my-project --set license=NotARealLicense

# Set the environment variable !env reads, to see it flow through instead of the default
ATMOS_EXAMPLE_MAINTAINER="Jane Doe" atmos scaffold generate example ./my-project --set license=MIT

The first command generates NOTICE.md and atmos.yaml (this whole directory is source: "." for the example template, like in examples/scaffolding) — but never lib/licenses.yaml itself. NOTICE.md reads (branch and maintainer will vary; shown here with the defaults and without running atmos scaffold generate inside a git repository):

# License Notice

This project is licensed under **MIT License**.

See: https://opensource.org/licenses/MIT

Generated from branch `unknown` by the project team.

Key Files

File	Purpose
scaffold.yaml	Template configuration: a license select field sourced from !include, a license_lookup computed field holding the same file's raw data, and generated_from_branch/maintainer computed fields sourced from !git.branch/!env
lib/licenses.yaml	The shared reference table both license-related fields include — never copied into generated output
NOTICE.md	Discovered template file, reads .Config.license_lookup, .Config.generated_from_branch, and .Config.maintainer
atmos.yaml	Registers this directory as the example template, and is copied verbatim into generated output for the same reason README.md is in examples/scaffolding
README.md	This file, also copied verbatim into generated output

Learn More

These YAML functions resolve before schema validation runs, not just before generation — atmos scaffold validate catches a missing local file, an unreachable remote source, a YQ filter producing the wrong shape, or a malformed function call, the same way atmos scaffold generate does. Only functions that need no stack, component, or backend context are supported in scaffold.yaml — see the atmos scaffold generate docs for the full reference, including remote (git::, oci://, https://) !include sources and the complete supported-tag list.