How to implement cross-origin resource sharing by using Go SDK - Object Storage Service

Due to the same-origin policy of browsers, cross-origin requests may be rejected when data is exchanged or resources are shared between different domain names. To resolve the issue, you can configure cross-origin resource sharing (CORS) rules. In the CORS rules, you can specify the domain names from which requests can be sent, the methods that can be used to send cross-origin requests, and the allowed headers.

Usage notes

In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions and endpoints.
In this topic, access credentials are obtained from environment variables. For more information about how to configure access credentials, see Configure access credentials.
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 Configure OSSClient instances.
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.

Sample code

Set CORS rules

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

package main

import (
	"log"

	"github.com/aliyun/aliyun-oss-go-sdk/oss"
)

func main() {
	// Set bucketName to the name of your bucket.
	bucketName := "yourBucketName"

	// Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set.
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		log.Fatalf("Error creating credentials provider: %v", err)
	}

	// Create an OSSClient instance.
	// Set yourEndpoint to the Endpoint of the bucket. For example, for a bucket in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. For other regions, use the actual Endpoint.
	// Set yourRegion to the region where the bucket is located. For example, for a bucket in the China (Hangzhou) region, set the region to cn-hangzhou. For other regions, use the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Set the signature version.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Error creating OSS client: %v", err)
	}

	isTrue := true
	rule1 := oss.CORSRule{
		AllowedOrigin: []string{"*"},
		AllowedMethod: []string{"PUT", "GET", "POST"},
		AllowedHeader: []string{},
		ExposeHeader:  []string{},
		MaxAgeSeconds: 100,
	}

	rule2 := oss.CORSRule{
		AllowedOrigin: []string{"http://www.a.com", "http://www.b.com"},
		AllowedMethod: []string{"GET"},
		AllowedHeader: []string{"Authorization"},
		ExposeHeader:  []string{"x-oss-test-01", "x-oss-test-02"},
		MaxAgeSeconds: 100,
	}

	put := oss.PutBucketCORS{}
	put.CORSRules = []oss.CORSRule{rule1, rule2}
	put.ResponseVary = &isTrue

	// Set the CORS rules.
	err = client.SetBucketCORSV2(bucketName, put)
	if err != nil {
		log.Fatalf("Error setting CORS rules: %v", err)
	}

	log.Println("Set Success")
}

Get CORS rules

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

package main

import (
	"log"

	"github.com/aliyun/aliyun-oss-go-sdk/oss"
)

func main() {
	// Set bucketName to the name of your bucket.
	bucketName := "yourBucketName"

	// Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set.
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		log.Fatalf("Error creating credentials provider: %v", err)
	}

	// Create an OSSClient instance.
	// Set yourEndpoint to the Endpoint of the bucket. For example, for a bucket in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. For other regions, use the actual Endpoint.
	// Set yourRegion to the region where the bucket is located. For example, for a bucket in the China (Hangzhou) region, set the region to cn-hangzhou. For other regions, use the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Set the signature version.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Error creating OSS client: %v", err)
	}

	// Get the CORS rules.
	corsRes, err := client.GetBucketCORS(bucketName)
	if err != nil {
		log.Fatalf("Error getting CORS rules: %v", err)
	}

	// Print the CORS rules.
	for _, rule := range corsRes.CORSRules {
		log.Printf("Cors Rules Allowed Origin: %v", rule.AllowedOrigin)
		log.Printf("Cors Rules Allowed Method: %v", rule.AllowedMethod)
		log.Printf("Cors Rules Allowed Header: %v", rule.AllowedHeader)
		log.Printf("Cors Rules Expose Header: %v", rule.ExposeHeader)
		log.Printf("Cors Rules Max Age Seconds: %d", rule.MaxAgeSeconds)
	}

	if corsRes.ResponseVary != nil {
		log.Printf("Cors Rules Response Vary: %t", *corsRes.ResponseVary)
	}
}

Delete CORS rules

The following sample code provides an example on how to delete all CORS rules of a specific bucket:

package main

import (
	"log"

	"github.com/aliyun/aliyun-oss-go-sdk/oss"
)

func main() {
	// Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set.
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		log.Fatalf("Error creating credentials provider: %v", err)
	}

	// Create an OSSClient instance.
	// Set yourEndpoint to the Endpoint of the bucket. For example, for a bucket in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. For other regions, use the actual Endpoint.
	// Set yourRegion to the region where the bucket is located. For example, for a bucket in the China (Hangzhou) region, set the region to cn-hangzhou. For other regions, use the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Set the signature version.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Error creating OSS client: %v", err)
	}

	// Set bucketName to the name of the bucket, for example, examplebucket.
	bucketName := "examplebucket"

	// Delete the CORS rules.
	err = client.DeleteBucketCORS(bucketName)
	if err != nil {
		log.Fatalf("Error deleting CORS rules: %v", err)
	}

	log.Println("Delete Bucket CORS Success")
}

References

For the complete sample code for CORS, see GitHub sample.
For more information about the API operation used to set CORS rules, see SetBucketCORSV2.
For more information about the API operation used to retrieve CORS rules, see GetBucketCORS.
For more information about the API operation used to delete CORS rules, see DeleteBucketCORS.