A example of template_file using Terraform

readme.md

Using terraform_file

$ terraform init
$ terraform plan
$ terraform apply

$ cat output.json // you can see any variable have been replaced with Vars

{
  "apiVersion": "vlabs",
  "properties": {
    "orchestratorProfile": {
      "orchestratorType": "Kubernetes"
    },
    "masterProfile": {
      "count": 1,
      "dnsPrefix": "edwin-k8s",
      "vmSize": "Standard_D2_v2"
    },
    "agentPoolProfiles": [
      {
        "name": "agentpool1",
        "count": 3,
        "vmSize": "Standard_D2_v2",
        "availabilityProfile": "AvailabilitySet"
      }
    ],
    "linuxProfile": {
      "adminUsername": "azureuser",
      "ssh": {
        "publicKeys": [
          {
            "keyData": "key_data"
          }
        ]
      }
    },
    "servicePrincipalProfile": {
      "clientId": "client_id",
      "secret": "secret"
    }
  }
}

example.tpl

{
  "apiVersion": "vlabs",
  "properties": {
    "orchestratorProfile": {
      "orchestratorType": "Kubernetes"
    },
    "masterProfile": {
      "count": 1,
      "dnsPrefix": "edwin-k8s",
      "vmSize": "Standard_D2_v2"
    },
    "agentPoolProfiles": [
      {
        "name": "agentpool1",
        "count": 3,
        "vmSize": "Standard_D2_v2",
        "availabilityProfile": "AvailabilitySet"
      }
    ],
    "linuxProfile": {
      "adminUsername": "azureuser",
      "ssh": {
        "publicKeys": [
          {
            "keyData": "${KEY_DATA}"
          }
        ]
      }
    },
    "servicePrincipalProfile": {
      "clientId": "${CLIENT_ID}",
      "secret": "${SECRET}"
    }
  }
}

main.tf

data "template_file" "init" {
  template = "${file("./example.tpl")}"

  vars {
    KEY_DATA = "key_data"
    CLIENT_ID = "client_id"
    SECRET = "secret"
  }
}

variable "output_file_name" {
  default = "result.json"
}

resource "null_resource" "test" {
  triggers {
    test = "${data.template_file.init.rendered}"
  }
  provisioner "local-exec" {
        command = "${format("cat <<\"EOF\" > \"%s\"\n%s\nEOF", var.output_file_name, data.template_file.init.rendered)}"
  }
}