Terraform 1 15

Terraform 1.15

This overview applies when the project's target Terraform version is at least 1.15.

Modules and types

• Module source and version arguments can refer to variables and local values. Commands that resolve modules therefore accept variable inputs.
• Output blocks can declare an explicit type constraint, allowing an output's public contract to be checked and converted at the module boundary.
• convert(value, type) performs an explicit inline type conversion using a type expression.

Deprecation

• Variable and output blocks can set deprecated to emit warnings when callers assign the variable or consumers reference the output.
• Provider-supplied deprecation messages for resources, blocks, and attributes appear in Terraform's warning diagnostics.

CLI, testing, and platforms

• terraform validate validates backend type and configuration. Workflows that supply partial backend settings with -backend-config must account for the validation behaviour of the installed patch release.
• Terraform test mock blocks can define functions.
• Saved plans are workspace-bound; applying a plan created for another workspace raises an error.
• Windows ARM64 is an official build target.
• The S3 backend supports authentication through aws login.

Experimental alpha features

• Alpha builds can allow deferred actions with terraform plan -allow-deferral, including unknown count and for_each values. This remains unavailable in stable Terraform 1.15.
• Alpha builds include persistent failed-test state, terraform test cleanup, test backends, and skip_cleanup. Do not rely on these features in stable configurations.