Pre-signed URL

Overview

The SDK for Node.js provides APIs to get object URLs and pre-signed request URLs. For more information, see the directions and examples in this document.

Signature Calculation

In all COS XML API requests, private resource operations require the authentication credential "authorization" which is used to determine whether the current request is legal.

There are two ways to use the authorization:

1. Put it in the header parameter (field name: authorization).
2. Put i in the URL parameter (field name: sign).

The COS.getAuthorization method is used to calculate the authorization, i.e., signing information used to verify the request validity.

This method is recommended only for frontend debugging. It is not recommended to use it in real projects as there may be a risk of key disclosure.

Use Cases

Obtain the authorization for file download:

var Authorization = COS.getAuthorization({
    SecretId: 'COS_SECRETID',
    SecretKey: 'COS_SECRETKEY',
    Method: 'get',
    Key: 'a.jpg',
    Expires: 60,
    Query: {},
    Headers: {}
});

Parameter Descriptions

Return Value Description

The return value is the calculated authentication credential string "authorization".

Getting a Pre-signed Request URL

Sample Download Request

Sample 1. Get an object URL without signature

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

Sample 2. Get a signed object URL

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

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

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

Sample 4. Specify validity period of the link

cos.getObjectUrl({
    Bucket: 'examplebucket-1250000000',
    Region: 'ap-beijing',
    Key: '1.jpg',
    Sign: true,
    Expires: 3600, // In seconds
}, 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: 'ap-beijing',
    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);
});

Sample Request for Upload

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

var request = require('request');
var fs = require('fs');
cos.getObjectUrl({
    Bucket: 'examplebucket-1250000000',
    Region: 'ap-beijing',
    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 Descriptions

Return Value Description

The return value is a string in the following two cases:

1. If the signature can be calculated synchronously (for example, passing in the SecretId and SecretKey through instantiation), the signed URL will be returned by default.
2. Otherwise; a URL with no signature will be returned.

Callback Function Description

function(err, data) { ... }