Download Pre-signed Object

If you want to allow others to receive the object without providing your credential keys, you can use the pre-signed download method.

Components

• Bucket Name
• Object Name
• Link Expiration Time (Optional)

Object Name (Key)

Object name we want to download.

.NET

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier:  Apache - 2.0

using Amazon;
using Amazon.S3;
using Amazon.S3.Model;
using System;
using System.Threading.Tasks;
using System.Reflection;

namespace DownloadPresignedObject
{
  class DownloadPresignedObject
  {
      private static IAmazonS3 _s3Client;

      private const string BUCKET_NAME = "<OBJECT_NAME>";
      private const string OBJECT_NAME = "<BUCKET_NAME>";

      static void Main()
      {
          var awsCredentials = new Amazon.Runtime.BasicAWSCredentials("<ACCESS-KEY>", "<SECRET-KEY>");
          var config = new AmazonS3Config { ServiceURL = "<ENDPOINT>" };
          _s3Client = new AmazonS3Client(awsCredentials, config);

          GeneratePreSignedUrl();
      }

      private static void GeneratePreSignedUrl()
      {
          try
          {
              // Create the request
              var getPreSignedUrlRequest = new GetPreSignedUrlRequest
              {
                  BucketName = BUCKET_NAME,
                  Key = OBJECT_NAME,
                  Expires = DateTime.Now.AddHours(1.0),
                  Verb = HttpVerb.GET
              };

              // Submit the request
              string url = _s3Client.GetPreSignedURL(getPreSignedUrlRequest);
              Console.WriteLine($"URL: {url}");
          }
          catch (AmazonS3Exception amazonS3Exception)
          {
              Console.WriteLine("An AmazonS3Exception was thrown. Exception: " + amazonS3Exception.ToString());
          }
          catch (Exception e)
          {
              Console.WriteLine("Exception: " + e.ToString());
          }
      }
  }
}

PHP

<?php
require('client.php');

$cmd = $client->getCommand('GetObject', [
  'Bucket' => $config['sample_bucket'],
  'Key' => 'file-uploaded-from-php-sdk.png'
]);

$request = $client->createPresignedRequest($cmd, '+20 minutes');

// Get the actual presigned-url
$presignedUrl = (string)$request->getUri();
echo $presignedUrl;

Python

import boto3
import logging
from botocore.exceptions import ClientError

# Configure logging
logging.basicConfig(level=logging.INFO)

try:
   s3_client = boto3.client(
       's3',
       endpoint_url='endpoint_url',
       aws_access_key_id='access_key',
       aws_secret_access_key='secret_key'
   )

except Exception as exc:
   logging.error(exc)
else:
   try:
       bucket = 'bucket-name'
       object_name = 'file.txt'

       response = s3_client.generate_presigned_url(
           'get_object',
           Params={
               'Bucket': bucket,
               'Key': object_name
           },
           ExpiresIn=3600
       )
   except ClientError as e:
       logging.error(e)

Javascript

// Import required AWS SDK clients and commands for Node.js
const { S3Client, GetObjectCommand } = require('@aws-sdk/client-s3');
const { S3RequestPresigner } = require('@aws-sdk/s3-request-presigner');
const { createRequest } = require('@aws-sdk/util-create-request');
const { formatUrl } = require('@aws-sdk/util-format-url');

// Create an S3 client service object
const s3 = new S3Client({
  region: 'default',
  endpoint: 'endpoint_url',
  forcePathStyle: false,
  credentials: {
      accessKeyId: 'access_key',
      secretAccessKey: 'secret_key',
  },
});

const clientParams = {
  Bucket: 'sample_bucket',
  Key: 'file.png',
};

const signedRequest = new S3RequestPresigner(s3.config);

const run = async () => {
  try {
      // Create request
      const request = await createRequest(
          s3,
          // new GetObjectCommand(clientParams)
          new GetObjectCommand(clientParams)
      );
      // Create and format presigned URL
      const signedUrl = formatUrl(
          await signedRequest.presign(request, {
              // Supply expiration in second
              expiresIn: 60 * 60 * 24,
          })
      );
      console.log(`download url: ${signedUrl}`);
  } catch (err) {
      console.log('Error creating presigned URL', err);
  }
};
run();

GO

package main

import (
  "fmt"
  "log"
  "os"
  "time"

  "github.com/aws/aws-sdk-go/aws"
  "github.com/aws/aws-sdk-go/aws/credentials"
  "github.com/aws/aws-sdk-go/aws/session"
  "github.com/aws/aws-sdk-go/service/s3"
)

// Downloads an item from an S3 Bucket
//
// Usage:
//    go run s3_download_presigned.go BUCKET FILE_NAME
func main() {

  if len(os.Args) != 3 {
      exitErrorf("Bucket name required\nUsage: go run", os.Args[0], "BUCKET", "FILE_NAME")
  }

  bucket := os.Args[1]
  filename := os.Args[2]
  // Initialize a session in us-west-2 that the SDK will use to load
  // credentials from the shared credentials file ~/.aws/credentials.
  sess, err := session.NewSession(&aws.Config{
      Credentials: credentials.NewStaticCredentials("<ACCESS_KEY>", "<SECRET_KEY>", ""),
  })
  svc := s3.New(sess, &aws.Config{
      Region:   aws.String("default"),
      Endpoint: aws.String("<ENDPOINT_URL>"),
  })

  req, _ := svc.GetObjectRequest(&s3.GetObjectInput{
      Bucket: aws.String(bucket),
      Key:    aws.String(filename),
  })
  urlStr, err := req.Presign(15 * time.Minute)

  if err != nil {
      log.Println("Failed to sign request", err)
  }

  log.Println("The URL is", urlStr)
}

// snippet-start:[s3.go.set_cors.exit]
func exitErrorf(msg string, args ...interface{}) {
  fmt.Fprintf(os.Stderr, msg+"\n", args...)
  os.Exit(1)
}

The following command can be used to execute the aforementioned code, presuming the code file is called s3_get_bucket_cors.go:

go run s3_download_presigned.go BUCKET FILE_NAME