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Deep Merge

docs/src/data/experiments/deep-merge.mdx

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Support for the deep_merge HCL function.

deep-merge - What it does

When enabled, Terragrunt exposes a deep_merge(map1, map2, ...) HCL function for combining map or object values.

For overlapping keys, values from later arguments override earlier arguments. Nested maps are merged recursively, lists are appended, and null arguments are ignored.

This is useful when building inputs from multiple JSON, YAML, or HCL-derived maps without having to rely on include block merge behavior.

bash
terragrunt run --all --experiment deep-merge -- plan

deep-merge - How to provide feedback

Provide your feedback in the deep-merge GitHub Discussion.

deep-merge - Criteria for stabilization

To transition the deep-merge feature to a stable release, the following must be addressed:

  • Confirm the merge semantics are useful for common configuration layering workflows.
  • Confirm type handling for decoded JSON/YAML and native HCL objects matches user expectations.
  • Positive feedback from users relying on the function in production pipelines.