CDKTF issue https://github.com/hashicorp/terraform-cdk/issues/2420

cdk.tf.json

{
  "//": {
    "metadata": {
      "backend": "local",
      "stackName": "test",
      "version": "0.14.3"
    },
    "outputs": {
      "test": {
        "test": "test"
      }
    }
  },
  "output": {
    "test": {
      "sensitive": false,
      "value": "https://${var.CLUSTER_DOMAIN}:${var.CLUSTER_PORT_HTTPS}/"
    }
  },
  "provider": {
    "kubernetes": [
      {
      }
    ]
  },
  "resource": {
    "kubernetes_config_map_v1": {
      "config": {
        "//": {
          "metadata": {
            "path": "test/config",
            "uniqueId": "config"
          }
        },
        "data": {
          "config": "${yamlencode({url = \"https://${var.CLUSTER_DOMAIN}:var.CLUSTER_PORT_HTTPS/\"})}"
        },
        "metadata": {
          "name": "test"
        }
      }
    }
  },
  "terraform": {
    "backend": {
      "local": {
        "path": ".../terraform.test.tfstate"
      }
    },
    "required_providers": {
      "kubernetes": {
        "source": "kubernetes",
        "version": "2.16.1"
      }
    }
  },
  "variable": {
    "CLUSTER_DOMAIN": {
      "sensitive": false,
      "type": "string"
    },
    "CLUSTER_PORT_HTTPS": {
      "sensitive": false,
      "type": "number"
    }
  }
}

configmap.yaml

apiVersion: v1
data:
  config: |
    "url": "https://cluster.local:var.CLUSTER_PORT_HTTPS/"
immutable: false
kind: ConfigMap
metadata:
  creationTimestamp: "2022-12-12T16:47:20Z"
  name: test
  namespace: default
  resourceVersion: "6425"
  uid: 7cd788f0-91a1-4d0d-84a8-6765dd056db8

output

$ dotenv -- cdktf deploy --auto-approve --ignore-missing-stack-dependencies network
network  Initializing the backend...
network  Initializing provider plugins...
         - Reusing previous version of hashicorp/kubernetes from the dependency lock file
network  - Reusing previous version of hashicorp/helm from the dependency lock file
network  - Reusing previous version of gavinbunney/kubectl from the dependency lock file
network  - Using previously-installed hashicorp/helm v2.7.1
network  - Using previously-installed gavinbunney/kubectl v1.14.0
network  - Using previously-installed hashicorp/kubernetes v2.16.0
network  Terraform has been successfully initialized!

         You may now begin working with Terraform. Try running "terraform plan" to see
         any changes that are required for your infrastructure. All Terraform commands
         should now work.

         If you ever set or change modules or backend configuration for Terraform,
         rerun this command to reinitialize your working directory. If you forget, other
         commands will detect it and remind you to do so if necessary.
network  Terraform used the selected providers to generate the following execution
         plan. Resource actions are indicated with the following symbols:
           + create

         Terraform will perform the following actions:

           # kubernetes_config_map_v1.config (config) will be created
           + resource "kubernetes_config_map_v1" "config" {
               + data = {
                   + "config" = <<-EOT
                         "url": "https://cluster.local:var.CLUSTER_PORT_HTTPS/"
                     EOT
                 }
               + id   = (known after apply)

               + metadata {
                   + generation       = (known after apply)
                   + name             = "test"
                   + namespace        = "default"
                   + resource_version = (known after apply)
                   + uid              = (known after apply)
                 }
             }

         Plan: 1 to add, 0 to change, 0 to destroy.

         Changes to Outputs:
           ~ test = "https://login.cluster.local:8443" -> "https://cluster.local:8443/"

         ─────────────────────────────────────────────────────────────────────────────

         Saved the plan to: plan

         To perform exactly these actions, run the following command to apply:
             terraform apply "plan"
network  kubernetes_config_map_v1.config (config): Creating...
network  kubernetes_config_map_v1.config (config): Creation complete after 0s [id=default/test]
network
         Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

         Outputs:

         test = "https://cluster.local:8443/"

  network
  test = https://cluster.local:8443/

✨  Done in 5.61s.

stack.ts

import { Construct } from "constructs";
import { Fn, TerraformOutput, TerraformStack, TerraformVariable } from "cdktf";
import { ConfigMapV1 } from "@cdktf/provider-kubernetes/lib/config-map-v1";
import { KubernetesProvider } from "@cdktf/provider-kubernetes/lib/provider";

export class TestStack extends TerraformStack {
  constructor(scope: Construct, id: string, props?: {}) {
    super(scope, id);

    new KubernetesProvider(this, "kubernetes", {});

    const clusterDomain = new TerraformVariable(this, "CLUSTER_DOMAIN", {
      type: "string",
      sensitive: false,
    });

    const clusterPortHttps = new TerraformVariable(this, "CLUSTER_PORT_HTTPS", {
      type: "number",
      sensitive: false,
    });

    new TerraformOutput(this, "test", {
      value: `https://${clusterDomain.stringValue}:${clusterPortHttps.numberValue}/`,
      sensitive: false,
    });

    new ConfigMapV1(this, "config", {
      metadata: {
        name: "test",
      },
      data: {
        config: Fn.yamlencode({
          url: `https://${clusterDomain.stringValue}:${clusterPortHttps.numberValue}/`,
        }),
      },
    });
  }
}