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    Generating Pre-Signed URL

    Last updated: 2024-02-04 11:37:32
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      Overview

      Node.js SDK provides APIs for getting object URLs and pre-signed request URLs. For details, see the descriptions and samples below.
      Note:
      You are advised to use a temporary key to generate pre-signed URLs for the security of your requests such as uploads and downloads. When you apply for a temporary key, follow the Principle of Least Privilege to avoid leaking resources besides your buckets and objects. Note that the action for applying for a temporary key needs to be added with the "name/cos:GetObject" permission.
      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.

      Signature Calculation

      In all COS XML API requests, the authentication credential Authorization is required for all operations on private resources for COS to determine whether a request is valid.
      There are two ways to use the authentication credential:
      1. Put it in the header parameter; field name: authorization.
      2. Put it in the URL parameter; field name: sign.
      The COS.getAuthorization method is used to calculate the authentication credential (Authorization), which is the signing information used to verify the validity of the request.
      Note:
      We recommend you use this method only for frontend debugging but not in actual projects, as it may disclose keys.

      Sample code

      Obtaining the authentication credential for file download:
      // Log in to https://console.tencentcloud.com/cam/capi to check and manage the SecretId and SecretKey of your project.
      var COS = require('cos-nodejs-sdk-v5');
      var Authorization = COS.getAuthorization({
        SecretId: process.env.SecretId, // User `SecretId`. We recommend that you obtain it from the environment variable. In addition, we recommend that you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1.
        SecretKey: process.env.SecretKey, // User `SecretKey`. We recommend that you obtain it from the environment variable. In addition, we recommend that you use a sub-account key and follow the principle of least privilege to reduce risks. For information about how to obtain a sub-account key, visit https://www.tencentcloud.com/document/product/598/37140?from_cn_redirect=1.
        Method: 'get',
        Key: 'a.jpg',
        Expires: 60,
        Query: {},
        Headers: {},
      });

      Parameter description

      Parameter
      Description
      Type
      Required
      SecretId
      Your SecretId.
      String
      Yes
      SecretKey
      Your SecretKey.
      String
      Yes
      Method
      HTTP request method such as GET, POST, DELETE, or HEAD
      String
      Yes
      Key
      Object key (object name) is the unique ID of an object in a bucket. If the request operation is to be performed on a file, this parameter is required and should be a filename. If the operation is on a bucket, this parameter should be left empty.
      String
      No
      Query
      Request parameters to be included in the signature in the format of {key: 'val'}
      Object
      No
      Headers
      Request headers to be included in the signature in the format of {key: 'val'}
      Object
      No
      Expires
      Signature expiration time in seconds. Default value: 900.
      Number
      No

      Return value description

      The return value is the calculated authentication credential string authorization.

      Getting a Pre-signed Request URL

      Download request samples

      Sample 1. Get an unsigned object URL
      var url = cos.getObjectUrl({
        Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
        Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
        Key: '1.jpg', /* Object key stored in the bucket (required), such as `1.jpg` and `a/b/test.txt`. */
        Sign: false,
      });
      Sample 2. Get a signed object URL
      var url = cos.getObjectUrl({
        Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
        Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
        Key: 'Profile photo.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
      });
      Sample 3. If the signing process is asynchronous, you need to get the signed URL through a callback
      cos.getObjectUrl(
        {
          Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
          Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
          Key: 'Profile photo.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
          Sign: false,
        },
        function (err, data) {
          console.log(err || data.Url);
        }
      );
      Sample 4. Specify the validity period of a link
      cos.getObjectUrl(
        {
          Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
          Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
          Key: 'Profile photo.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
          Sign: true,
          Expires: 3600, // Unit: second
        },
        function (err, data) {
          console.log(err || data.Url);
        }
      );
      Sample 5. Get the file URL and download the file
      var request = require('request');
      var fs = require('fs');
      cos.getObjectUrl(
        {
          Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
          Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
          Key: 'Profile photo.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
          Sign: true,
        },
        function (err, data) {
          if (err) return console.log(err);
          console.log(data.Url);
          var req = request(data.Url, function (err, response, body) {
            console.log(err || body);
          });
          var writeStream = fs.createWriteStream(__dirname + '/1.jpg');
          req.pipe(writeStream);
        }
      );
      Sample 6. Generate the pre-signed URL with the signature containing Query and Header
      cos.getObjectUrl(
        {
          Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
          Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
          Key: 'Profile photo.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
          Sign: true,
          /* The HTTP request parameters passed in should be the same as those of the actual request. This can prevent users from tampering with the HTTP request parameters. */
          Query: {
            'imageMogr2/thumbnail/200x/': '',
          },
          /* The HTTP request headers passed in should be included in the actual request. This can prevent users from tampering with the HTTP request headers that are signed here. */
          Headers: {
            host: 'xxx', /* Specified host for access. Error code 403 will be reported for access by a non-specified host. */
          },
        },
        function (err, data) {
          console.log(err || data.Url);
        }
      );

      Upload request samples

      Sample 1. Get a pre-signed URL for Put Object upload
      var request = require('request');
      var fs = require('fs');
      cos.getObjectUrl(
        {
          Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
          Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
          Key: 'Profile photo.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
          Method: 'PUT',
          Sign: true,
        },
        function (err, data) {
          if (err) return console.log(err);
          console.log(data.Url);
          var readStream = fs.createReadStream(__dirname + '/1.jpg');
          var req = request(
            {
              method: 'PUT',
              url: data.Url,
            },
            function (err, response, body) {
              console.log(err || body);
            }
          );
          readStream.pipe(req);
        }
      );

      Parameter description

      Parameter
      Description
      Type
      Required
      Bucket
      Bucket name in the format of BucketName-APPID.
      String
      Yes
      Region
      Bucket region. For the enumerated values, see Regions and Access Endpoints.
      String
      Yes
      Key
      Object key (object name) is the unique ID of an object in a bucket. If the request operation is to be performed on a file, this parameter is required and should be a filename. If the operation is on a bucket, this parameter should be left empty.
      String
      Yes
      Sign
      Whether to return a signed URL. Default value: true.
      Boolean
      No
      Protocol
      Valid values: http: (default value), https:.
      String
      No
      Domain
      Bucket access domain name. Default value: {BucketName-APPID}.cos.{Region}.myqcloud.com.
      String
      No
      Method
      HTTP request method such as GET, POST, DELETE, or HEAD. Default value: GET.
      String
      No
      Query
      Request parameters to be included in the signature in the format of {key: 'val'}
      Object
      No
      Headers
      Request headers to be included in the signature in the format of {key: 'val'}
      Object
      No
      Expires
      Signature expiration time in seconds. Default value: 900.
      Number
      No

      Returned value description

      A string is returned in one of the two ways:
      1. If the signature can be calculated synchronously (for example, the SecretId and SecretKey have been passed in during instantiation), the signed URL will be returned by default.
      2. Otherwise, an unsigned URL will be returned.

      Callback function description

      function(err, data) { ... }
      Parameter
      Description
      Type
      err
      Error code, which is returned when an error (network error or service error) occurs. If the request is successful, this parameter is empty. For more information, please see Error Codes.
      Object
      data
      The object returned when the request is successful. If an error occurs with the request, this parameter is empty.
      Object
      - Url
      Calculated URL
      String
      
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