terragrunt CAS integrates with stacks through update_source_with_cas
Introduced 2026-04-27 · score 0.96
HOW TO USE IT
When a catalog unit uses a relative source path, set `update_source_with_cas = true` and generate the stack with CAS enabled; Terragrunt rewrites the source to a `cas::` reference. The v1.0.3 release note says to enable the `cas` experiment, but current documentation no longer lists CAS as an experiment.
unit "service" {
source = "../..//units/my-service"
update_source_with_cas = true
path = "service"
}
terragrunt stack generate --experiment casWHY THIS HELPS
Generate a stack from catalog units whose Terraform source paths are relative to the catalog repository.
BEFORE THIS CHANGE
Without CAS, catalog authors used remote Git URLs and threaded the reference through `values` expressions.
REQUIREMENTS AND LIMITATIONS
- Version: v1.0.3
- Availability: The `cas` experiment is required.
- source (required): Relative source path within the same repository; `//` separates the repository base path from the subdirectory.
- update_source_with_cas: Set to `true` to rewrite a nested relative source to a `cas::` reference during stack generation.
- path (required): Relative destination path for the generated unit.
- stack generate (required): Generates stack units from discovered `terragrunt.stack.hcl` configurations.
- Prerequisite: The relative source must stay within the same repository; `--no-cas` must not be set.
- Prerequisite: The v1.0.3 release note says the `cas` experiment must be enabled. Current active-experiment docs do not list CAS as an experiment.
- The repository is cloned once; subsequent stack generations resolve content from the local store without network access.
- Docs conflict: Current documentation describes CAS integration but no longer documents the `cas` experiment enable flag; it may describe behavior newer than v1.0.3.
FIRST-PARTY EVIDENCE
- https://github.com/gruntwork-io/terragrunt/releases/tag/v1.0.3
- https://docs.terragrunt.com/features/stacks/explicit/
- https://docs.terragrunt.com/reference/cli/commands/stack/generate/
Check the installed version and the source before using it. Entry JSON