Object Storage Service:Manage symbolic links (Go SDK V1)

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 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 set.
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		log.Fatalf("Failed to create 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("Failed to create OSS client: %v", err)
	}

	// Specify the bucket name, for example, examplebucket.
	bucketName := "examplebucket"
	// Specify the name of the symbolic link, for example, examplesymlink.txt.
	symObjectKey := "examplesymlink.txt"
	// Specify the name of the target object that the symbolic link points to, for 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 an object with the same name. A value of true overwrites the object. A value of false does not.
		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")
}

Get the name of the target object

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 set.
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		log.Fatalf("Failed to create 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("Failed to create OSS client: %v", err)
	}

	// Specify the bucket name, for 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)
	}

	// Get the name of the target object that the symbolic link points to.
	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 to create symbolic links, see PutSymlink.

• For more information about the API operation to retrieve symbolic links, see GetSymlink.