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Generating Pre-Signed URL

Last updated: 2023-09-13 10:59:41

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Feature Overview

This document provides an overview of SDK code samples related to generating pre-signed object URLs.
For instructions on using pre-signed URLs for uploads, please refer to Pre-signed Authorization Upload. For instructions on using pre-signed URLs for downloads, please refer to Pre-signed Authorization Download.
Note
To learn about signature rules, see Request Signature.
We recommend users to generate pre-signed URLs using temporary keys to further enhance the security of pre-signed upload, download, and other requests through temporary authorization. When applying for temporary keys, please follow the Principle of Least Privilege to prevent the leakage of resources beyond the target storage bucket or object.
If you need to use a permanent key to generate a pre-signed URL, you are advised to limit the permission of the permanent key to uploads and downloads only to avoid risks.

Generating a Pre-Signed URL for Downloading Objects

Note

This API is used to generate a pre-signed URL for downloading COS objects.

Sample code

// Bucket name in the format of <1>BucketName-APPID</1> (<3>APPID</3> is required), which can be viewed in the COS console at https://console.cloud.tencent.com/cos5/bucket.
let bucket = "examplebucket-1250000000";
// The location of the object in the bucket, i.e., the object key
let cosPath = "exampleobject";
// URL request parameters
let requestParameters = {"test1k":"test1v", "test2k":"test2v"};
try {
  // Obtain pre-signed download URL for an object
  String objectUrl = await Cos.getDefaultService().getPresignedUrl(
    bucket, 
    cosPath, 
    {
      parameters: requestParameters
}
  );
} catch (e) {
  // An exception will be thrown upon failure, handle the error accordingly
  console.log(e);
}

Description

Parameter name
Description
Local Disk Types
Required
bucket
Bucket name follows the naming convention BucketName-APPID. For more information, please refer to Bucket Overview.
String
Required
cosPath
The Object Key is the unique identifier of an object within a storage bucket. For example, in the object access domain examplebucket-1250000000.cos.ap-guangzhou.myqcloud.com/doc/picture.jpg, the Object Key is doc/picture.jpg.
String
Required
signValidTime
Signature validity period, in seconds. Note that this is the signature validity period. You need to ensure the key validity period by yourself.
Int
Not required
signHost
Whether to include the Host header in the signature. You can choose not to include it, but the request may fail or vulnerabilities may occur.
Bool
Not required
parameters
HTTP request parameters, which should be the same as those passed to the actual request. This can prevent users from tampering with the HTTP request parameters.
Map
Not required

Response description

Success: A pre-signed URL for downloading objects is returned.
Failure: An error occurs (e.g., authentication failure), and an exception CosXmlClientError or CosXmlServiceError is thrown. For more information, please refer to Error Handling.
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