Terraform: Terraform should fail when interpolating nonexistent template vars in output variable

[bspaans]

Terraform Version

0.8.8

Affected Resource(s)

• data template_file
• output variables
• probably more resources that depend on the output variable

Terraform Configuration Files

in main.tf

module "test" {
  source = "module1/"
}

module "test2" {
  source = "module2/"
  input_var = "${module.test.my_output}"
}

in module1/test.tf

data "template_file" "tpl" {
  template = "whatever"
  vars = {
  }
}

output "my_output" {
  value = "${data.template_file.tpl.vars.doesntexist}"
}

in module2/test.tf

variable "input_var" { }

data "template_file" "tpl2" {
  template = "$${OtherVariable}"
  vars = {
    OtherVariable = "test"
    Variable = "${var.input_var}"
  }
}

Expected Behavior

Referencing the nonexistent variable in the output variable should have failed with an error.

Actual Behavior

Apply fails with: * data.template_file.tpl2: failed to render : 1:3: unknown variable accessed: OtherVariable

Note that it's failing on the "wrong" variable, which caused some head-scratching.

Steps to Reproduce

1. terraform get
2. terraform apply

[jbardin]

Related to #12403. Once outputs can produce errors, this may take care of itself.

[ketzacoatl]

Bump, silent failures like this lead to really bad problems down the pipeline.

EDIT, the related tickets have been closed, so maybe this is also resolved?

EDIT: #12403 was a dupe of #9080.

[jbardin]

Thanks @ketzacoatl, this also should have been closed.
The next release will have even more type information, and can present an error even earlier.

You would see something along the lines of:

Error: Missing map element

  on module1/main.tf line 9, in output "my_output":
   9:   value = data.template_file.tpl.vars.doesntexist
    |----------------
    | data.template_file.tpl.vars is map of string with 0 elements

This map does not have an element with the key "doesntexist".

[hashibot[bot]]

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