Terraform: Get current Git commit SHA

README.md

This will return the full Git commit SHA of whichever branch is currently checkedout.

Dump the snippet into terraform console (run from within a Git repo) to see for yourself.

git_commit_sha.tf

trimspace(file(".git/${trimspace(trimprefix(file(".git/HEAD"), "ref:"))}"))

If you are using Terraform Cloud or Terraform Enterprise you can use the TFC_CONFIGURATION_VERSION_GIT_COMMIT_SHA environment variable.

variable "TFC_CONFIGURATION_VERSION_GIT_COMMIT_SHA" {
  type = string
}

and reference it as vars.TFC_CONFIGURATION_VERSION_GIT_COMMIT_SHA

https://developer.hashicorp.com/terraform/cloud-docs/run/run-environment#environment-variables