Object Storage Service:Manage symbolic links

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, 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 create a symbolic link, you must have the oss:PutObject permission. To query a symbolic link, you must have the oss:GetObject permission. For more information, see Attach a custom policy to a RAM user.

Create a symbolic link

The following sample code provides an example on how to create a symbolic link:

package main

import (
	"log"

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

func main() {
	// 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. 
	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)
	}

	// Specify the name of the bucket. Example: examplebucket. 
	bucketName := "examplebucket"
	// Specify the name of the symbolic link. Example: examplesymlink. 
	symObjectKey := "examplesymlink.txt"
	// Specify the name of the object to which the symbolic link points. Example: exampleobject.txt. 
	objectName := "exampleobject.txt"

	bucket, err := client.Bucket(bucketName)
	if err != nil {
		log.Fatalf("Failed to get bucket '%s': %v", bucketName, err)
	}

	// Create the symbolic link. 
	options := []oss.Option{
		// Specify whether to overwrite the object that has the same name as the symbolic link. A value of true specifies that the object is overwritten. A value of false specifies that the object is not overwritten. 
		oss.ForbidOverWrite(true),
		// Specify the access control list (ACL) of the object. In this example, the ACL is set to private. 
		oss.ObjectACL(oss.ACLPrivate),
		// Specify the storage class of the object. In this example, the storage class is set to Standard. 
		oss.StorageClass(oss.StorageStandard),
	}

	err = bucket.PutSymlink(symObjectKey, objectName, options...)
	if err != nil {
		log.Fatalf("Failed to create symlink '%s' pointing to '%s': %v", symObjectKey, objectName, err)
	}

	log.Println("Symlink created successfully")
}

Query the name of the object to which a symbolic link points

To query a symbolic link, you must have read permissions on the symbolic link. The following sample code provides an example on how to query a symbolic link and the name of the object to which the symbolic link points:

package main

import (
	"log"

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

func main() {
	// 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. 
	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)
	}

	// Specify the name of the bucket. Example: examplebucket. 
	bucketName := "examplebucket"
	// Specify the name of the symbolic link. 
	symlinkName := "examplesymlink.txt"

	bucket, err := client.Bucket(bucketName)
	if err != nil {
		log.Fatalf("Failed to get bucket '%s': %v", bucketName, err)
	}

	// Query the name of the object to which the symbolic link points. 
	meta, err := bucket.GetSymlink(symlinkName)
	if err != nil {
		log.Fatalf("Failed to get symlink '%s': %v", symlinkName, err)
	}

	target := meta.Get(oss.HTTPHeaderOssSymlinkTarget)
	log.Printf("Symlink '%s' points to: %s", symlinkName, target)
}

References

• For more information about the API operation that you can call to create a symbolic link, see PutSymlink.

• For more information about the API operation that you can call to query a symbolic link, see GetSymlink.