Configure bucket policies to authorize or restrict user access to OSS by using OSS SDK for Go - Object Storage Service

A bucket policy allows you to authorize or restrict access of anonymous users or identified users, such as Alibaba Cloud accounts, RAM users, and RAM roles, to specific Object Storage Service (OSS) resources. For example, you can grant read-only permissions on specific OSS resources to a RAM user of another Alibaba Cloud account.

Usage notes

Before you configure bucket policies, make sure that you are familiar with this feature. For more information, see Bucket policies.

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, endpoints and open ports.
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 Initialization.
To configure a bucket policy, you must have the oss:PutBucketPolicy permission. To query bucket policies, you must have the oss:GetBucketPolicy permission. To delete a bucket policy, you must have the oss:DeleteBucketPolicy permission. For more information, see Attach a custom policy to a RAM user.

Sample code

Configure bucket policies

The following sample code provides an example on how to configure a bucket policy:

package main

import (
	"log"

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

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

	// Create an OSSClient instance. 
	// 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. Specify your actual endpoint. 
	// Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. Specify the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Specify the version of the signature algorithm.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Failed to create OSS client: %v", err)
	}

	// In the following example, the bucket owner whose UID is 174649585760xxxx uses a bucket policy to authorize a RAM user whose UID is 20214760404935xxxx to list all objects in examplebucket. 
	policyConfig := `
    {
        "Statement": [
            {
                "Action": [
                    "oss:GetObject",
                    "oss:ListObjects"
                ],
                "Principal": [
                    "20214760404935xxxx"           
                ],
                "Effect" : "Allow",
                "Resource" : ["acs:oss:*:174649585760xxxx:examplebucket/*"]
            }
        ],
        "Version": "1"
    }`

	// Configure the bucket policy. 
	bucketName := "examplebucket"
	err = client.SetBucketPolicy(bucketName, policyConfig)
	if err != nil {
		log.Fatalf("Failed to set bucket policy for '%s': %v", bucketName, err)
	}

	log.Println("SetBucketPolicy success")
}

Query bucket policies

The following sample code shows how to query bucket policies:

package main

import (
	"log"

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

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

	// Create an OSSClient instance. 
	// 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. Specify your actual endpoint.
	// Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. Specify the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Specify the version of the signature algorithm.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Failed to create OSS client: %v", err)
	}

	// Query the configurations of the bucket policies.     
	bucketName := "yourBucketName"
	strPolicy, err := client.GetBucketPolicy(bucketName)
	if err != nil {
		log.Fatalf("Failed to get bucket policy for '%s': %v", bucketName, err)
	}

	log.Printf("Bucket policy for '%s': %s", bucketName, strPolicy)
}

Delete bucket policies

The following sample code provides an example on how to delete a bucket policy:

package main

import (
	"log"

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

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

	// Create an OSSClient instance. 
	// 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. Specify your actual endpoint.
	// Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. Specify the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Specify the version of the signature algorithm.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		log.Fatalf("Failed to create OSS client: %v", err)
	}

	// Delete the bucket policy.
	bucketName := "yourBucketName"
	err = client.DeleteBucketPolicy(bucketName)
	if err != nil {
		log.Fatalf("Failed to delete bucket policy for '%s': %v", bucketName, err)
	}

	log.Println("DeleteBucketPolicy success")
}

References

For more information about the API operation that you can call to configure a bucket policy, see SetBucketPolicy.
For more information about the API operation that you can call to query bucket policies, see GetBucketPolicy.
For more information about the API operation that you can call to delete a bucket policy, see DeleteBucketPolicy.