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Bucket Policy
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Last updated: 2025-06-12 17:43:52
Bucket Policy
Last updated: 2025-06-12 17:43:52
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Overview

This document provides an API overview of bucket policies and SDK example code.

Notes

COS C# SDK v5.4.39 or above is required.

Related Examples

Feature Name
Description
Sample code
PUT Bucket policy
Set the permission policy for the specified bucket.
GET Bucket policy
Query the permission policy for the specified bucket.
Deleting a Bucket Policy
Delete the permission policy for the specified bucket.

Preliminary Preparation: Initialize COS Service Instance

public class AccessManageModel
{
    private CosXml cosXml; //Set the service user as a data member
    // Initialize COS service instance
    private void InitCosXml()
    {
        string region = Environment.GetEnvironmentVariable("COS_REGION");
        CosXmlConfig config = new CosXmlConfig.Builder()
            .SetRegion(region) // Set default region. For abbreviations of COS regions, see https://www.tencentcloud.com/document/product/436/6224?from_cn_redirect=1
            .Build();
        string secretId = Environment.GetEnvironmentVariable("SECRET_ID"); // Cloud API key SecretId, see https://console.tencentcloud.com/cam/capi to obtain API key
        string secretKey = Environment.GetEnvironmentVariable("SECRET_KEY"); // cloud API key SecretKey, obtain API key see https://console.tencentcloud.com/cam/capi
        long durationSecond = 600; //Request signature valid duration for each request, in seconds
        QCloudCredentialProvider qCloudCredentialProvider = new DefaultQCloudCredentialProvider(secretId, secretKey, durationSecond);
        this.cosXml = new CosXmlServer(config, qCloudCredentialProvider);
    }
}

Case

PUT Bucket policy

The PUT Bucket policy API can write a permission policy to a bucket. If the bucket already has a permission policy, the policy uploaded in this request will overwrite the existing one.
public void PutBucketPolicy()
{
    string bucket = "examplebucket-1250000000";
    PutBucketPolicyRequest request = new PutBucketPolicyRequest(bucket);
    string policy = @"{
           ""Statement"": [
               {
                   ""Action"": [
                       ""name/cos:PutBucketPolicy"",
                       ""name/cos:GetBucketPolicy"",
                       ""name/cos:DeleteBucketPolicy""
                   ],
                   ""Effect"": ""Allow"",
                   ""Principal"": {
                       ""qcs"": [
                           ""qcs::cam::uin/100000000001:uin/100000000002""
                       ]
                   },
                   ""Resource"": [
                       ""qcs::cos:ap-guangzhou:uid/1250000000:examplebucket-1250000000/*""
                   ]
               }
           ],
           ""Version"": ""2.0""
      }";
    request.SetBucketPolicy(policy);
    PutBucketPolicyResult result = cosXml.PutBucketPolicy(request);
    Console.WriteLine(result.GetResultInfo());
}

Parameter Description

Parameter Name
Description
Required
Statement
Describe the detailed information of one or more permissions
Yes
Version
Syntax version of a policy, which is 2.0 by default.
Yes
Principal
Describe the entity authorized by the policy. For details, see Overview of Access Policy Language.
Yes
Action
Here refers to the COS API. Specify a combination of one or a sequence of operations or all operations (*) as required, for example, the action is name/cos:GetService. Please note that the case is case-sensitive.
Yes
Effect
The options include allow (permission) and deny (explicit deny).
Yes
Resource
Authorized data to be operated, which can be any resources, resources with a specified path prefix, resources with a specified absolute path, or resources with combinations of the above conditions.
Yes
Condition
Constraint conditions, which can be left blank. For details, see condition description.
No

GET Bucket policy

The GET Bucket policy API is used to read the permission policy of a bucket.
public void GetBucketPolicy()
{
    string bucket = "examplebucket-1250000000";
    GetBucketPolicyRequest  request = new GetBucketPolicyRequest(bucket);
    GetBucketPolicyResult result = cosXml.GetBucketPolicy(request);
    Console.WriteLine(result.Data); //Return Data, in json format
    Console.WriteLine(result.GetResultInfo());
}

Deleting a Bucket Policy

The DELETE Bucket policy request can be used to delete the permission policy for a bucket.
public void DeleteBucketPolicy()
{  
    string bucket = "examplebucket-1250000000";
    DeleteBucketPolicyRequest  request = new DeleteBucketPolicyRequest(bucket);
    DeleteBucketPolicyResult result = cosXml.DeleteBucketPolicy(request);
    Console.WriteLine(result.GetResultInfo());
}

API Operations

For the API interface description of setting a bucket policy, please see the PUT Bucket policy document.
For the API interface description of querying a bucket policy, please see the GET Bucket policy document.
For the API interface description of deleting a bucket policy, please see the DELETE Bucket policy document.
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