Pre-Signed URL

Last updated: 2021-08-18 10:57:34

    Overview

    Node.js SDK provides APIs for getting object URLs and pre-signed request URLs. For details, see the descriptions and samples below.

    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 request validity.

    Note:

    It is recommended that this method is only used for frontend debugging but not in actual projects, as it may disclose keys.

    Use case

    Obtaining the authentication credential for file download:

    // Log in to the [CAM console](https://console.cloud.tencent.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: 'SECRETID',
       SecretKey: 'SECRETKEY',
       Method: 'get',
       Key: 'a.jpg',
       Expires: 60,
       Query: {},
       Headers: {}
    });
    

    Parameter description

    Parameter Description Type Required
    SecretId User's SecretId String No
    SecretKey User's SecretKey String Yes
    Method HTTP request method such as GET, POST, DELETE, or HEAD String Yes
    Key Object key (object name), a 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 query parameter object of the request Object No
    Headers header parameter object of the request Object No
    Expires Signature expiration time in seconds. Default value: 900 seconds Number No

    Returned value

    The returned value is the calculated authentication credential string authorization.

    Getting a Pre-signed Request URL

    Samples for download requests

    Sample 1. Get an unsigned object URL

    var url = cos.getObjectUrl({
       Bucket: 'examplebucket-1250000000',
       Region: 'COS_REGION',
       Key: '1.jpg',
       Sign: false
    });
    

    Sample 2. Get a signed object URL

    var url = cos.getObjectUrl({
       Bucket: 'examplebucket-1250000000',
       Region: 'COS_REGION',
       Key: '1.jpg'
    });
    

    Sample 3. If the signing process is asynchronous, you need to get the signed URL through a callback

    cos.getObjectUrl({
       Bucket: 'examplebucket-1250000000',
       Region: 'COS_REGION',
       Key: '1.jpg',
       Sign: false
    }, function (err, data) {
       console.log(err || data.Url);
    });
    

    Sample 4. Specify the validity period of a link

    cos.getObjectUrl({
       Bucket: 'examplebucket-1250000000',
       Region: 'COS_REGION',
       Key: '1.jpg',
       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',
       Region: 'COS_REGION',
       Key: '1.jpg',
       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);
    });
    

    Samples for upload requests

    Sample 1. Get a pre-signed URL for Put Object upload

    var request = require('request');
    var fs = require('fs');
    cos.getObjectUrl({
       Bucket: 'examplebucket-1250000000',
       Region: 'COS_REGION',
       Method: 'PUT',
       Key: '1.jpg',
       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, please 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 It can be http: (default) or https: String No
    Domain Bucket access domain. 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 query parameter object used in signature calculation Object No
    Headers header parameter object used in signature calculation Object No
    Expires Signature expiration time in seconds. Default value: 900 seconds 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 Object returned when an error (network error or service error) occurs. If the request is successful, this parameter is left empty. For more information, please see Error Codes. Object
    data Object returned when the request is successful. If the request fails, this parameter is left empty Object
    - Url Calculated URL String