Help Center/ Object Storage Service/ SDK Reference/ Node.js/ Bucket Management (SDK for Node.js)/ Obtaining the Policy of a Bucket (SDK for Node.js)
Updated on 2024-11-13 GMT+08:00

Obtaining the Policy of a Bucket (SDK for Node.js)

Function

OBS provides access control over buckets. You can use an access policy to define whether a user can perform certain operations on a specific bucket. OBS access control can be implemented using IAM permissions, bucket policies, and ACLs. For more information, see Introduction to OBS Access Control.

A bucket policy is applied to a configured bucket and the objects in it. You can use a bucket policy to grant permission for the bucket and the objects in it to IAM users or other accounts. If you want IAM users to have different permissions for different buckets, you need to configure different bucket policies for those users.

This API returns the policy of a bucket.

Restrictions

  • OBS returns "404 NoSuchBucketPolicy" when you call this API in the following scenarios:
    • The specified bucket policy does not exist.
    • The standard policy of the specified bucket is set to Private and no advanced policies are configured.
  • To obtain the policy of a bucket, you must be the bucket owner or have the required permission (obs:bucket:GetBucketPolicy in IAM or GetBucketPolicy in a bucket policy). For details, see Introduction to OBS Access Control, IAM Custom Policies, and Creating a Custom Bucket Policy.
  • To learn about the mappings between OBS regions and endpoints, see Regions and Endpoints.

Method

ObsClient.getBucketPolicy(params)

Request Parameters

Table 1 BucketRequestInput

Parameter

Type

Mandatory (Yes/No)

Description

Bucket

string

Yes

Explanation:

Bucket name.

Restrictions:

  • A bucket name must be unique across all accounts and regions.
  • A bucket name:
    • Must be 3 to 63 characters long and start with a digit or letter. Lowercase letters, digits, hyphens (-), and periods (.) are allowed.
    • Cannot be formatted as an IP address.
    • Cannot start or end with a hyphen (-) or period (.).
    • Cannot contain two consecutive periods (..), for example, my..bucket.
    • Cannot contain a period (.) and a hyphen (-) adjacent to each other, for example, my-.bucket or my.-bucket.
  • If you repeatedly create buckets with the same name in the same region, no error will be reported, and the bucket attributes comply with those set in the first creation request.

Value range:

The value can contain 3 to 63 characters.

Default value:

None

Responses

Table 2 Responses

Type

Description

Table 3

NOTE:

This API returns a Promise response, which requires the Promise or async/await syntax.

Explanation:

Returned results. For details, see Table 3.

Table 3 Response

Parameter

Type

Description

CommonMsg

ICommonMsg

Explanation:

Common information generated after an API call is complete, including the HTTP status code and error code. For details, see Table 4.

InterfaceResult

Table 5

Explanation:

Results outputted for a successful call. For details, see Table 5.

Restrictions:

This parameter is not included if the value of Status is greater than 300.

Table 4 ICommonMsg

Parameter

Type

Description

Status

number

Explanation:

HTTP status code returned by the OBS server.

Value range:

A status code is a group of digits indicating the status of a response. It ranges from 2xx (indicating successes) to 4xx or 5xx (indicating errors). For details, see Status Codes.

Code

string

Explanation:

Error code returned by the OBS server.

Message

string

Explanation:

Error description returned by the OBS server.

HostId

string

Explanation:

Request server ID returned by the OBS server.

RequestId

string

Explanation:

Request ID returned by the OBS server.

Id2

string

Explanation:

Request ID2 returned by the OBS server.

Indicator

string

Explanation:

Error code details returned by the OBS server.

Table 5 GetBucketPolicyOutput

Parameter

Type

Description

RequestId

string

Explanation:

Request ID returned by the OBS server

Policy

string

Explanation:

Policy in JSON format

Restrictions:

  • The bucket name contained in the Resource parameter of the policy must be the same as the one specified for the current bucket policy.
  • For details about the policy format, see Bucket Policy Parameters.

Code Examples

This example returns the policy of bucket examplebucket.

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// Import the OBS library.
// Use npm to install the client.
const ObsClient = require("esdk-obs-nodejs");
// Use the source code to install the client.
// var ObsClient = require('./lib/obs');

// Create an instance of ObsClient.
const obsClient = new ObsClient({
  //Obtain an AK/SK pair using environment variables or import an AK/SK pair in other ways. Using hard coding may result in leakage.
  //Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/intl/en-us/usermanual-ca/ca_01_0003.html.
  access_key_id: process.env.ACCESS_KEY_ID,
  secret_access_key: process.env.SECRET_ACCESS_KEY,
  // (Optional) If you use a temporary AK/SK pair and a security token to access OBS, you are advised not to use hard coding, which may result in information leakage. You can obtain an AK/SK pair using environment variables or import an AK/SK pair in other ways.
  // security_token: process.env.SECURITY_TOKEN,
  // Enter the endpoint corresponding to the region where the bucket is located. CN-Hong Kong is used here in this example. Replace it with the one currently in use.
  server: "https://obs.ap-southeast-1.myhuaweicloud.com"
});

async function getBucketPolicy() {
  try {
    const params = {
      // Specify the bucket name.
      Bucket: "examplebucket"
    };
    // Obtain the bucket policy.
    const result = await obsClient.getBucketPolicy(params);
    if (result.CommonMsg.Status <= 300) {
      console.log("Get bucket(%s)'s policy successful!", params.Bucket);
      console.log("RequestId: %s", result.CommonMsg.RequestId);
      console.log("Policy: %s", result.InterfaceResult.Policy);
      return;
    };
    console.log("An ObsError was found, which means your request sent to OBS was rejected with an error response.");
    console.log("Status: %d", result.CommonMsg.Status);
    console.log("Code: %s", result.CommonMsg.Code);
    console.log("Message: %s", result.CommonMsg.Message);
    console.log("RequestId: %s", result.CommonMsg.RequestId);
  } catch (error) {
    console.log("An Exception was found, which means the client encountered an internal problem when attempting to communicate with OBS, for example, the client was unable to access the network.");
    console.log(error);
  };
};

getBucketPolicy();