```hcl
/*
 * Copyright 2017 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


/*
 * Terraform variable declarations for GCP.
 */

variable gcp_credentials_file_path {
  description = "Locate the GCP credentials .json file."
  type = "string"
}

variable "gcp_project_id" {
  description = "GCP Project ID."
  type = "string"
}

variable gcp_region {
  description = "Default to Oregon region."
  default = "us-west1"
}

variable gcp_instance_type {
  description = "Machine Type. Correlates to an network egress cap."
  default = "n1-standard-1"
}

variable gcp_disk_image {
  description = "Boot disk for gcp_instance_type."
  default = "projects/debian-cloud/global/images/family/debian-9"
}
```

Fix Terraform warnings: Quoted type constraints are deprecated
user
```hcl
/*
 * Copyright 2017 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


/*
 * Terraform variable declarations for GCP.
 */

variable gcp_credentials_file_path {
  description = "Locate the GCP credentials .json file."
  type = string
}

variable "gcp_project_id" {
  description = "GCP Project ID."
  type = string
}

variable gcp_region {
  description = "Default to Oregon region."
  default = "us-west1"
}

variable gcp_instance_type {
  description = "Machine Type. Correlates to an network egress cap."
  default = "n1-standard-1"
}

variable gcp_disk_image {
  description = "Boot disk for gcp_instance_type."
  default = "projects/debian-cloud/global/images/family/debian-9"
}
```
assistant