[Yandex Cloud documentation](../../index.md) > [Yandex API Gateway](../index.md) > [Step-by-step guides](index.md) > Managing an API gateway > Setting up variables

# Setting up variables

API Gateway supports [variables in the OpenAPI specification](../concepts/extensions/parametrization.md).

{% cut "Example of a specification file with a variable" %}

```yaml
openapi: 3.0.0
info:
  title: Sample API
  version: 1.0.0

x-yc-apigateway:
  variables:
    environment:
      default: "prod"
      enum:
        - "prod"
        - "testing"
        - "dev"
      description: "API Gateway installation."

paths:
  /env/info:
    get:
      x-yc-apigateway-integration:
        type: dummy
        content:
          '*': It is ${var.environment} environment!
        http_code: 200
        http_headers:
          Content-Type: text/plain
```

{% endcut %}

By default, variables take the values specified in the `default` field of the [OpenAPI specification](https://en.wikipedia.org/wiki/OpenAPI_Specification). You can override them by providing other values when setting up your [API gateway](../concepts/index.md):

{% list tabs group=instructions %}

- Management console {#console}

  1. In the [management console](https://console.yandex.cloud), go to the [folder](../../resource-manager/concepts/resources-hierarchy.md#folder) where you want to update an API gateway.
  1. Navigate to **API Gateway**.
  1. In the API gateway row, click ![image](../../_assets/options.svg) and select ![image](../../_assets/console-icons/pencil.svg) **Edit**.
  1. Under **Variable settings**, list all the variables declared in the specification and their values.
  1. Click **Save**.

- CLI {#cli}

  If you do not have the Yandex Cloud CLI yet, [install and initialize it](../../cli/quickstart.md#install).

  The folder used by default is the one specified when [creating](../../cli/operations/profile/profile-create.md) the CLI profile. To change the default folder, use the `yc config set folder-id <folder_ID>` command. You can also specify a different folder for any command using `--folder-name` or `--folder-id`. If you access a resource by its name, the search will be limited to the default folder. If you access a resource by its ID, the search will be global, i.e., through all folders based on access permissions.

  To set up your variables:
  1. Edit the OpenAPI specification file or create a new one, if required.
  1. View the description of the CLI command for updating an API gateway:

     ```bash
     yc serverless api-gateway update --help
     ```

  1. Specify the API gateway ID or name in the command and list all the variables declared in the specification as `key=value`:

     ```bash
     yc serverless api-gateway update \
       --id <API_gateway_ID> \
       --variables <list_of_variables>
     ```

- Terraform {#tf}

  With [Terraform](https://www.terraform.io/), you can quickly create a cloud infrastructure in Yandex Cloud and manage it using configuration files. These files store the infrastructure description written in HashiCorp Configuration Language (HCL). If you change the configuration files, Terraform automatically detects which part of your configuration is already deployed, and what should be added or removed.
  
  Terraform is distributed under the [Business Source License](https://github.com/hashicorp/terraform/blob/main/LICENSE). The [Yandex Cloud provider for Terraform](https://github.com/yandex-cloud/terraform-provider-yandex) is distributed under the [MPL-2.0](https://www.mozilla.org/en-US/MPL/2.0/) license.
  
  For more information about the provider resources, see the relevant documentation on the [Terraform](https://www.terraform.io/docs/providers/yandex/index.html) website or [its mirror](../../terraform/index.md).

  If you do not have Terraform yet, [install it and configure the Yandex Cloud provider](../../tutorials/infrastructure-management/terraform-quickstart.md#install-terraform).
  
  
  To manage infrastructure using Terraform under a service account or user accounts (a Yandex account, a federated account, or a local user), [authenticate](../../terraform/authentication.md) using the appropriate method.

  To provide the values of the variables declared in the API gateway specification:
  1. Open the Terraform configuration file and add the `variables` section to it:

     ```hcl
     resource "yandex_api_gateway" "<API_gateway_name>" {
       ...
       variables = {
         <list_of_variables>
       }
       ...
     }
     ```

     List the variables in `key = value` format, such as:

     ```hcl
     resource "yandex_api_gateway" "<API_gateway_name>" {
       ...
       variables = {
         environment = "testing"
       }
       ...
     }
     ```

  1. Check the configuration using this command:

     ```bash
     terraform validate
     ```

     If the configuration is valid, you will get this message:

     ```text
     Success! The configuration is valid.
     ```

  1. Run this command:

     ```bash
     terraform plan
     ```

     You will see a list of resources and their properties. No changes will be made at this step. Terraform will show any errors in the configuration.
  1. Apply the configuration changes:

     ```bash
     terraform apply
     ```

  1. Type `yes` and press **Enter** to confirm the changes.

     You can check the API gateway update using the [management console](https://console.yandex.cloud) or this [CLI](../../cli/index.md) command:

     ```bash
     yc serverless api-gateway get <API_gateway_name>
     ```

- API {#api}

  To set up variables for an API gateway specification, use the [update](../apigateway/api-ref/ApiGateway/update.md) REST API method for the [ApiGateway](../apigateway/api-ref/ApiGateway/index.md) resource or the [ApiGatewayService/Update](../apigateway/api-ref/grpc/ApiGateway/update.md) gRPC API call.

{% endlist %}

## See also

* [How specification parameterization works](../concepts/extensions/parametrization.md)
* [How to update an API gateway specification](api-gw-update.md)