Terraform CLI
Terraform one function received too many elements
Error: Invalid function argument
Terraform could not use one because the collection contains more than one element, while one only accepts zero-or-one collections.
Error AtlasError Documentation and ResolutionObserved message
Error: Invalid function argument
Why it happens
- The list, set, or tuple passed to one contains multiple elements.
- The configuration assumes a collection is optional-singleton, but runtime data returns more values.
- A count or for_each expression produces more results than the downstream expression expects.
How to fix it
- Check why the collection contains multiple elements and whether that is expected.
- Use a different expression pattern if the collection can legitimately contain more than one value.
- Constrain the upstream logic so one only receives zero-or-one collections.
Official reference
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