S3 Lib
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Node Amazon S3 Client.


  • Familiar API (client.get(), client.put(), etc)
  • Very Node-like low-level request capabilities via http.Client
  • Higher-level API with client.putStream(), client.getFile(), etc.
  • Copying and multi-file delete support
  • Streaming file upload and direct stream-piping support


The following examples demonstrate some capabilities of knox and the S3 REST API. First things first, create an S3 client:

var client = knox.createClient({
    key: '<api-key-here>'
  , secret: '<secret-here>'
  , bucket: 'learnboost'

More options are documented below for features like other endpoints or regions.


If you want to directly upload some strings to S3, you can use the Client#put method with a string or buffer, just like you would for any http.Client request. You pass in the filename as the first parameter, some headers for the second, and then listen for a 'response' event on the request. Then send the request using req.end(). If we get a 200 response, great!

var object = { foo: "bar" };
var string = JSON.stringify(object);
var req = client.put('/test/obj.json', {
    'Content-Length': string.length
  , 'Content-Type': 'application/json'
req.on('response', function(res){
  if (200 == res.statusCode) {
    console.log('saved to %s', req.url);

By default the x-amz-acl header is private. To alter this simply pass this header to the client request method.

client.put('/test/obj.json', { 'x-amz-acl': 'public-read' });

Each HTTP verb has an alternate method with the "File" suffix, for example put() also has a higher level method named putFile(), accepting a source filename and performing the dirty work shown above for you. Here is an example usage:

client.putFile('my.json', '/user.json', function(err, res){
  // Logic

Another alternative is to stream via Client#putStream(), for example:

http.get('http://google.com/doodle.png', function(res){
  var headers = {
      'Content-Length': res.headers['content-length']
    , 'Content-Type': res.headers['content-type']
  client.putStream(res, '/doodle.png', headers, function(err, res){
    // Logic

And if you want a nice interface for putting a buffer or a string of data, use Client#putBuffer():

var buffer = new Buffer('a string of data');
var headers = {
  'Content-Type': 'text/plain'
client.putBuffer(buffer, '/string.txt', headers, function(err, res){
  // Logic

Note that both putFile and putStream will stream to S3 instead of reading into memory, which is great. And they return objects that emit 'progress' events too, so you can monitor how the streaming goes! The progress events have fields written, total, and percent.


Below is an example GET request on the file we just shoved at S3. It simply outputs the response status code, headers, and body.

client.get('/test/Readme.md').on('response', function(res){
  res.on('data', function(chunk){

There is also Client#getFile() which uses a callback pattern instead of giving you the raw request:

client.getFile('/test/Readme.md', function(err, res){
  // Logic


Delete our file:

client.del('/test/Readme.md').on('response', function(res){

Likewise we also have Client#deleteFile() as a more concise (yet less flexible) solution:

client.deleteFile('/test/Readme.md', function(err, res){
  // Logic


As you might expect we have Client#head and Client#headFile, following the same pattern as above.

Advanced Operations

Knox supports a few advanced operations. Like copying files:

client.copy('/test/Readme.md', '/test/Readme.markdown').on('response', function(res){

// or

client.copyFile('/test/Readme.md', '/test/Readme.markdown', function(err, res){
  // Logic

and deleting multiple files at once:

client.deleteMultiple(['/test/Readme.md', '/test/Readme.markdown'], function(err, res){
  // Logic

and listing all the files in your bucket:

client.list({ prefix: 'my-prefix' }, function(err, data){
  /* `data` will look roughly like:

    Prefix: 'my-prefix',
    IsTruncated: true,
    MaxKeys: 1000,
    Contents: [
        Key: 'whatever'
        LastModified: new Date(2012, 11, 25, 0, 0, 0),
        ETag: 'whatever',
        Size: 123,
        Owner: 'you',
        StorageClass: 'whatever'



And you can always issue ad-hoc requests, e.g. the following to get an object's ACL:

client.request('GET', '/test/Readme.md?acl').on('response', function(res){
  // Read and parse the XML response.
  // Everyone loves XML parsing.

Multipart Upload

S3's multipart upload is their rather-complicated way of uploading large files. In particular, it is the only way of streaming files without knowing their Content-Length ahead of time.

Adding the complexity of multipart upload directly to knox is not a great idea. For example, it requires buffering at least 5 MiB of data at a time in memory, which you want to avoid if possible. Fortunately, @nathanoehlman has created the excellent knox-mpu package to let you use multipart upload with knox if you need it!

Client Creation Options

Besides the required key, secret, and bucket options, you can supply any of the following:


By default knox will send all requests to the global endpoint (bucket.s3.amazonaws.com). This works regardless of the region where the bucket is. But if you want to manually set the endpoint (for performance reasons) you can do it with the endpoint option.


For your convenience when using buckets not in the US Standard region, you can specify the region option. When you do so, the endpoint hostname is automatically assembled.

As of this writing, valid values for the region option are:

  • US Standard (default): us-standard
  • US West (Oregon): us-west-2
  • US West (Northern California): us-west-1
  • EU (Ireland): eu-west-1
  • Asia Pacific (Singapore): ap-southeast-1
  • Asia Pacific (Tokyo): ap-northeast-1
  • South America (Sao Paulo): sa-east-1

If new regions are added later, their subdomain names will also work when passed as the region option. See the AWS endpoint documentation for the latest list.

Convenience APIs such as putFile and putStream currently do not work as expected with buckets in regions other than US Standard without explicitly specify the region option. This will eventually be addressed by resolving issue #66; however, for performance reasons, it is always best to specify the region option anyway.

secure and port

By default, knox uses HTTPS to connect to S3 on port 443. You can override either of these with the secure and port options. Note that if you specify a custom port option, the default for secure switches to false, although you can override it manually if you want to run HTTPS against a specific port.


If you are using the AWS Security Token Service APIs, you can construct the client with a token parameter containing the temporary security credentials token. This simply sets the x-amz-security-token header on every request made by the client.


If you want to use a custom HTTP agent, you can specify this with the agent option.

Running Tests

To run the test suite you must first have an S3 account. Then create a file named ./test/auth.json, which contains your credentials as JSON, for example:

  "key": "<api-key-here>",
  "secret": "<secret-here>",
  "bucket": "<your-bucket-name>",
  "bucketUsWest2": "<bucket-in-us-west-2-region-here>"

Then install the dev dependencies and execute the test suite:

$ npm install
$ npm test