Updated on 2024-01-02 GMT+08:00

OPTIONS Bucket

Functions

OPTIONS refers to pre-requests that are sent to servers by clients. Generally, the requests are used to check whether clients have permissions to perform operations on servers. Only after a pre-request is returned successfully, clients start to execute the follow-up requests.

The OBS allows buckets to store static web resources. OBS buckets can serve as website resources if the buckets are properly used. In this scenario, buckets in the OBS serve as servers to process OPTIONS pre-requests from clients.

OBS can process OPTIONS pre-requests only after CORS is configured for buckets in OBS. For details about CORS, see Configuring Bucket CORS.

Differences Between OPTIONS Bucket and OPTIONS Object

With the OPTIONS Object, you need to specify an object name in the URL, but an object name is not required with the OPTIONS Bucket, which uses the bucket domain name as the URL. The request lines of the two methods are as follows:

OPTIONS /object HTTP/1.1
OPTIONS / HTTP/1.1

Request Syntax

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OPTIONS / HTTP/1.1 
Host: bucketname.obs.region.example.com
Date: date
Authorization: authorization
Origin: origin
Access-Control-Request-Method: method

Request Parameters

This request contains no message parameters.

Request Headers

This request uses the headers described in Table 1.

Table 1 OPTIONS request headers

Header

Description

Mandatory

Origin

Origin of the cross-domain request specified by the pre-request. Generally, it is a domain name set in CORS.

Type: string

Yes

Access-Control-Request-Method

An HTTP method that can be used by a request. The request can use multiple method headers.

Type: string

Value options: GET, PUT, HEAD, POST, DELETE

Yes

Access-Control-Request-Headers

HTTP headers of a request. The request can use multiple HTTP headers.

Type: string

No

Request Elements

This request involves no elements.

Response Syntax

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HTTP/1.1 status_code
Content-Type: application/xml 
Access-Control-Allow-Origin: origin
Access-Control-Allow-Methods: method
Access-Control-Allow-Header: header
Access-Control-Max-Age: time
Access-Control-Expose-Headers: header
Date: date
Content-Length: length

Response Headers

The response uses the following headers as described in Table 2.

Table 2 CORS response headers

Header

Description

Access-Control-Allow-Origin

If the origin of a request meets server CORS configuration requirements, the response contains the origin.

Type: string

Access-Control-Allow-Headers

If the headers of a request meet server CORS configuration requirements, the response contains the headers.

Type: string

Access-Control-Max-Age

Value of MaxAgeSeconds in the CORS configuration of a server

Type: integer

Access-Control-Allow-Methods

If the Access-Control-Request-Method of a request meets server CORS configuration requirements, the response contains the methods in the rule.

Type: string

Value options: GET, PUT, HEAD, POST, DELETE

Access-Control-Expose-Headers

Value of ExposeHeader in the CORS configuration of a server

Type: string

Response Elements

This response contains no elements.

Error Responses

Table 3 describes possible special errors in the request.

Table 3 Special error

Error Code

Description

HTTP Status Code

Bad Request

Invalid Access-Control-Request-Method: null

When CORS and OPTIONS are configured for a bucket, no method header is added.

400 BadRequest

Bad Request

Insufficient information. Origin request header needed.

When CORS and OPTIONS are configured for a bucket, no origin header is added.

400 BadRequest

AccessForbidden

CORSResponse: This CORS request is not allowed. This is usually because the evaluation of Origin, request method / Access-Control-Request-Method or Access-Control-Request-Headers are not whitelisted by the resource's CORS specification.

When CORS and OPTIONS are configured for a bucket, origin, method, and headers do not match any rule.

403 Forbidden

For other errors, see Table 2.

Sample Request

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OPTIONS / HTTP/1.1
User-Agent: curl/7.29.0
Host: examplebucket.obs.region.example.com
Accept: */*
Date: WED, 01 Jul 2015 04:02:15 GMT
Authorization: OBS H4IPJX0TQTHTHEBQQCEC:7RqP1vjemo6U+Adv9/Y6eGzWrzA=
Origin: www.example.com
Access-Control-Request-Method: PUT

Sample Response

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HTTP/1.1 200 OK
Server: OBS
x-obs-request-id: BF260000016436314E8FF936946DBC9C
Access-Control-Allow-Origin: www.example.com
Access-Control-Allow-Methods: POST,GET,HEAD,PUT,DELETE
Access-Control-Max-Age: 100
Access-Control-Expose-Headers: ExposeHeader_1,ExposeHeader_2
Access-Control-Allow-Credentials: true
x-obs-id-2: 32AAAQAAEAABAAAQAAEAABAAAQAAEAABCTlYimJvOyJncCLNm5y/iz6MAGLNxTuS
Date: WED, 01 Jul 2015 04:02:15 GMT
Content-Length: 0