Indent function in template file failed to render

[sebastien-prudhomme]

Terraform Version

Terraform v0.11.0 and Terraform v.0.10.8

Terraform Configuration Files

resource "tls_private_key" "ca" {
  algorithm = "RSA"
  rsa_bits  = "2048"
}

data "template_file" "config-yaml" {
  template = "${file("${path.module}/config.yaml.tpl")}"

  vars {
    ca_rsa_private = "${tls_private_key.ca.private_key_pem}"
  }
}

config.yaml.tpl:

ca_rsa_private: |
  ${indent(2, ca_rsa_private)}

Expected Behavior

No error

Actual Behavior

Got this error:

failed to render : 2:5: unknown function called: indent

Important Factoids

If i use the indent function directly in the TF file, it works fine.

data "template_file" "config-yaml" {
  template = "${file("${path.module}/config.yaml.tpl")}"

  vars {
    ca_rsa_private = "${indent(2, tls_private_key.ca.private_key_pem)}"
  }
}

config.yaml.tpl:

ca_rsa_private: |
  ${ca_rsa_private}

[apparentlymart]

Hi @sebastien-prudhomme,

Unfortunately this is the expected behavior today: the template_file interpolation context doesn't include Terraform's interpolation functions, since it's an entirely separate system.

We have plans in future to make templates a more "first-class" idea in Terraform, rather than a separate provider, and that would allow them to integrate more deeply with Terraform's value scope and interpolation functions. Unfortunately there's a fair amount of work we need to get done before we can do that, since it'll interact with the new version of the configuration language we're integrating currently.

In the mean time I think the best way to do this is to inline the "template" inside your config as a local value definition. This is not ideal because it doesn't allow your editor to see the result as YAML, but it allows the use of interpolation functions and avoids the need for defining a separate set of variables:

locals {
  config_yaml = <<EOT
ca_rsa_private: |
  ${indent(2, tls_private_key.ca.private_key_pem)}
EOT
}

Alternatively, you could exploit the fact that YAML accepts JSON syntax and instead assign this YAML attribute in JSON, at the expense of readability of the resulting YAML file:

ca_rsa_private: ${ca_rsa_private_json}

data "template_file" "config-yaml" {
  template = "${file("${path.module}/config.yaml.tpl")}"

  vars {
    ca_rsa_private_json = "${jsonencode(tls_private_key.ca.private_key_pem)}"
  }
}

...though indeed this isn't really much better than your example of passing in the already-indented string, except that it at least doesn't need to hard-code a specific indentation level and thus decouples the YAML file layout from the Terraform config.

[hashibot]

This issue has been automatically migrated to hashicorp/terraform-provider-template#23 because it looks like an issue with that provider. If you believe this is not an issue with the provider, please reply to this issue and let us know.

[sebastien-prudhomme]

Thanks for the explanation @apparentlymart , but perhaps the doc should be corrected: https://www.terraform.io/docs/configuration/interpolation.html

You may use any of the built-in functions in your template

[ghost]

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