To use the TF Sensu provider set the password via a env variable. The username is static in terragrunt.hcl. The password is located at engineering/sensu/sensu-prod/admin
SENSU_PASSWORD=
echo $SENSU_PASSWORD
If you are an idiot and add an ! to the password you can escape it like this:
e!password
export SENSU_PASSWORD=e\!password
Or, in one line to apply:
SENSU_PASSWORD=blah terragrunt apply