Configuring CORS when responding to clients

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Updated at October 28, 2024

Note

To make sure cross-domain requests work correctly, additionally set up CORS on a source if the source supports this mechanism. For example, CORS configuration is required for Object Storage buckets.

To configure cross-domain requests with CORS for the resource:

Management console

CLI

Terraform

API

In the management console, select the folder where your resource is located.
Select Cloud CDN.
Click the resource name.
Go to the HTTP headers and methods tab.
In the top-right corner, click Edit.
Under CORS when responding to client requests:
- In the Access-Control-Allow-Origin header field, specify whether to add this header to responses.
- When adding a header, select the values of the Origin header that allow access to the content. To grant access only to specific origins, select Same as Origin if on the list, specify the origin domain names and click Add domain name.
Click Save.

If you do not have the Yandex Cloud command line interface yet, install and initialize it.

The folder specified in the CLI profile is used by default. You can specify a different folder using the --folder-name or --folder-id parameter.

View the description of the CLI update resource command:
```
yc cdn resource update --help
```

Get a list of all resources in the default folder:

yc cdn resource list --format yaml

Result:

id: s0me1dkfjq********
folder_id: s0mef01der7p********
cname: testexample.com
created_at: "2022-01-19T09:23:57.921365Z"
updated_at: "2022-01-19T10:55:30.305141Z"
active: true
options:
  edge_cache_settings:
    enabled: true
    default value: "345600"
  cache_http_headers:
    enabled: true
    value:
    - content-type
    - content-length
    - connection
    - server
    - date
    - test
  stale:
    enabled: true
    value:
    - error
    - updating
  allowed_http_methods:
    value:
    - GET
    - POST
    - HEAD
    - OPTIONS
origin_group_id: "89783"
origin_group_name: My origins group
origin_protocol: HTTP
ssl_certificate:
  type: DONT_USE
  status: READY

To enable adding the Access-Control-Allow-Origin header, use the --cors flag:
```
yc cdn resource update <resource_ID> --cors <CORS_value>
```
The * and "$http_origin" values grant access to content with any Origin header value. To only grant access to specific origins, specify "$http_origin" and the origin domain names: ["domain.com", "second.dom.com"].

For more information about the yc cdn resource update command, see the CLI reference.

If you don't have Terraform, install it and configure the Yandex Cloud provider.

In the configuration file, describe the parameters of the CDN resource to create:
```
terraform {
  required_providers {
    yandex = {
      source  = "yandex-cloud/yandex"
      version = "0.69.0"
    }
  }
}

provider "yandex" {
  token     = "<OAuth_token>"
  cloud_id  = "<cloud_ID>"
  folder_id = "<folder_ID>"
  zone      = "<availability_zone>"
}

resource "yandex_cdn_resource" "my_resource" {
    cname               = "cdn1.yandex-example.ru"
    active              = false
    origin_protocol     = "https"
    secondary_hostnames = ["cdn-example-1.yandex.ru", "cdn-example-2.yandex.ru"]
    origin_group_id     = yandex_cdn_origin_group.my_group.id
    options {
      allowed_http_methods = ["GET","PUT"]
      cors                 = ["*"]
    }

}
```
Where:
- cname: Primary domain name used for content distribution. This is a required parameter.
- active: Flag indicating content availablity to end users. True: CDN content will be available to clients. This is an optional parameter. The default value is true.
- origin_protocol: Protocol for origins. This is an optional parameter. The default value is http.
- secondary_hostnames: Additional domain names. This is an optional parameter.
- origin_group_id: Origin group ID. This is a required parameter. Use the ID from the description of the origin group in the yandex_cdn_origin_group resource.
- The options section contains additional parameters of CDN resources:
  - cors: Value the CDN will send in the Access-Control-Allow-Origin header in response to a CORS request.
  - allowed_http_methods: HTTP methods allowed for your CDN content. By default, the following methods are allowed: GET, HEAD, POST, PUT, PATCH, DELETE, and OPTIONS. If the user is not allowed to use any method, they will get the 405 Method Not Allowed response. For methods that are not supported, the user will get 501 (Not Implemented). This is an optional parameter. Its default values are GET, HEAD, POST, and OPTIONS.
For more information about the yandex_cdn_resource parameters in Terraform, see the relevant provider documentation.
In the command line, go to the folder with the Terraform configuration file.
Check the configuration using this command:
```
terraform validate
```
If the configuration is correct, you will get this message:
```
Success! The configuration is valid.
```
Run this command:
```
terraform plan
```
The terminal will display a list of resources with parameters. No changes will be made at this step. If the configuration contains any errors, Terraform will point them out.
Apply the configuration changes:
```
terraform apply
```
Confirm the changes: type yes into the terminal and press Enter.

You can check the changes to the CDN resource in the management console or using this CLI command:
```
yc cdn resource list
```

Use the update REST API method for the Resource resource or the ResourceService/Update gRPC API call.

It may take up to 15 minutes for the new settings of the existing resource to apply to CDN servers. After that, we recommend purging the resource cache.

Configuring CORS when responding to clients

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