Object Storage Service:CORS

Usage notes

• In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS by using other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about the regions and endpoints supported by OSS, see Regions and endpoints.

• In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Initialization.

• To configure CORS rules, you must have the oss:PutBucketCors permission. To query CORS rules, you must have the oss:GetBucketCors permission. To delete CORS rules, you must have the oss:DeleteBucketCors permission. For more information, see Attach a custom policy to a RAM user.

Configure CORS rules

The following sample code provides an example on how to configure CORS rules for a specific bucket:

using Aliyun.OSS;
using Aliyun.OSS.Common;

// Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. 
var endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
var accessKeyId = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_ID");
var accessKeySecret = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_SECRET");
// Specify the name of the bucket. Example: examplebucket. 
var bucketName = "examplebucket";

// Create an OSSClient instance. 
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    var request = new SetBucketCorsRequest(bucketName);
    var rule1 = new CORSRule();
    // Specify the origins from which cross-origin requests are allowed. 
    rule1.AddAllowedOrigin("http://example.com");
    // Specify the methods that can be used to send cross-origin requests, including GET, PUT, DELETE, POST, and HEAD. 
    rule1.AddAllowedMethod("POST");
    // AllowedHeaders and ExposeHeaders do not support wildcard characters. 
    rule1.AddAllowedHeader("*");
    // Specify the response headers for allowed access requests from applications. 
    rule1.AddExposeHeader("x-oss-test");
    // You can configure up to 10 CORS rules for a bucket. 
    request.AddCORSRule(rule1);
    var rule2 = new CORSRule();
    // You can use only one asterisk (*) as a wildcard character for AllowedOrigins and AllowedMethods in a CORS rule. The asterisk (*) wildcard character specifies that all origins or operations are allowed. 
    rule2.AddAllowedOrigin("http://example.net");
    rule2.AddAllowedMethod("GET");
    // Specify whether the headers that are specified by Access-Control-Request-Headers in the OPTIONS preflight request are allowed. 
    rule2.AddExposeHeader("x-oss-test2");
    // Specify the period of time in which the browser can cache the response for an OPTIONS preflight request for specific resources. Unit: seconds. 
    rule2.MaxAgeSeconds = 100;
    request.AddCORSRule(rule2);
    // Configure the CORS rules. 
    client.SetBucketCors(request);
    Console.WriteLine("Set bucket:{0} Cors succeeded ", bucketName);
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error info: {0}; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

Query CORS rules

For the complete sample code that is used to query CORS rules, visit GitHub.

The following sample code provides an example on how to query CORS rules that are configured for a specific bucket:

using Aliyun.OSS;
using Aliyun.OSS.Common;
// Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. 
var endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
var accessKeyId = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_ID");
var accessKeySecret = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_SECRET");
// Specify the name of the bucket. Example: examplebucket. 
var bucketName = "examplebucket";

// Create an OSSClient instance. 
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    // Query the CORS rules. 
    var result = client.GetBucketCors(bucketName);
    Console.WriteLine("Get bucket:{0} Cors succeeded ", bucketName);
    foreach (var rule in result)
    {
        foreach (var origin in rule.AllowedOrigins)
        {
            Console.WriteLine("Allowed origin:{0}", origin);
        }
    }
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error info: {0}; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

Delete CORS rules

The following sample code provides an example on how to delete the CORS rules that are configured for a specific bucket:

using Aliyun.OSS;
using Aliyun.OSS.Common;
// Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. 
var endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
var accessKeyId = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_ID");
var accessKeySecret = Environment.GetEnvironmentVariable("OSS_ACCESS_KEY_SECRET");
// Specify the name of the bucket. Example: examplebucket. 
var bucketName = "examplebucket";

// Create an OSSClient instance. 
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    // Delete the CORS rules. 
    client.DeleteBucketCors(bucketName);
    Console.WriteLine("Delete bucket:{0} Cors succeeded ", bucketName);
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error info: {0} ; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

References

• For the complete sample code that is used to manage CORS, visit GitHub.

• For more information about the API operation that you can call to configure CORS rules, see PutBucketCors.

• For more information about the API operation that you can call to query CORS rules, see GetBucketCors.

• For more information about the API operation that you can call to delete CORS rules, see DeleteBucketCors.