cdktn-cli: 'get' subcommand fails when HCL has an in-line comment containing closing bracket

[josh-hook]

Expected Behavior

CDKTN should handle HCL variable type definitions which contain an in-line comment with a closing bracket.

Actual Behavior

CDKTN errors with an unknown type error.

cdktn get
⠋ starting...
[2026-02-18T15:57:23.519] [INFO] default - The CDKTN version has changed, generating all constraints. The previous veError: unknown type list(object({ # TODO - change to `map(object({...
    at mW (/Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:112:1008)
    at pW.emitSubmodule (/Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:112:2380)
    at new pW (/Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:112:1493)
    at Pre.generateTypescriptModule (/Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:114:76332)
    at Pre.generateTypescript (/Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:114:76559)
    at /Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:117:618
    at Array.map (<anonymous>)
    at Pre.generate (/Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:117:606)
    at async LUe (/Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:197:3611)
    at async /Users/joshh/cdk-terrain/packages/cdktn-cli/bundle/bin/cmds/handlers.js:514:17054
⠏ downloading and generating modules and providers...
Error: unknown type list(object({ # TODO - change to `map(object({...

Steps to Reproduce

1. Create a cdktf.json with:

{
  "language": "python",
  "terraformModules": [
    {
      "name": "karpenter",
      "source": "terraform-aws-modules/eks/aws//modules/karpenter",
      "version": "21.15.1"
    }
  ]
}

2. Run cdktf get
3. Observe the error

Versions

python 3.11.14
cdktn 0.22.0 (built from yarn build)

Providers

N/A

Gist

No response

Possible Solutions

The offending HCL can be seen here: https://github.com/terraform-aws-modules/terraform-aws-eks/blob/v21.15.1/modules/karpenter/variables.tf#L121

variable "iam_policy_statements" {
  description = "A list of IAM policy [statements](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/iam_policy_document#statement) - used for adding specific IAM permissions as needed"
  type = list(object({ # TODO - change to `map(object({...}))` in next major version
    sid           = optional(string)
    actions       = optional(list(string))
    not_actions   = optional(list(string))
    effect        = optional(string)
    resources     = optional(list(string))
    not_resources = optional(list(string))
    principals = optional(list(object({
      type        = string
      identifiers = list(string)
    })))
    not_principals = optional(list(object({
      type        = string
      identifiers = list(string)
    })))
    condition = optional(list(object({
      test     = string
      values   = list(string)
      variable = string
    })))
  }))
  default = null
}

Issue appears to be caused by the CDKTN code in packages/@cdktn/provider-schema/src/provider-schema.ts transformVariables function:

const matched = (variable["type"] as string)?.match(/\$\{(.*)\}/);
variableType = matched ? matched[1] : "any";

Since the regex does not match newlines, it ends up matching to the commented out } character, causing the resulting type to be parsed as list(object({ # TODO - change to map(object({..., which then later can't be parsed to an expression.

I managed to fix locally by replacing this with the following:

      const rawVariableType = variable["type"];
      if (
        typeof rawVariableType === "string" &&
        rawVariableType.startsWith("${") &&
        rawVariableType.endsWith("}") &&
        !rawVariableType.includes("\n")
      ) {
        variableType = rawVariableType.slice(2, -1);
      } else {
        variableType = "any";
      }

Which ensures the passed type string is fully encapsulated in a ${...}, and also persists the existing behaviour of not parsing multi-line type definitions.

Workarounds

No response

Anything Else?

Already fixed this locally, happy to submit a PR if the possible solutions sounds sensible!

References

Original issue submitted here: hashicorp/terraform-cdk#3940

Help Wanted

• I'm interested in contributing a fix myself

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