andrewrkHigh Level Amazon S3 Client
Features
- Automatically retry a configurable number of times when S3 returns an error.
- Includes logic to make multiple requests when there is a 1000 object limit.
- Ability to set a limit on the maximum parallelization of S3 requests. Retries get pushed to the end of the paralellization queue.
- Ability to sync a dir to and from S3.
- Progress reporting.
- Supports files of any size (up to S3's maximum 5 TB object size limit).
- Uploads large files quickly using parallel multipart uploads.
- Uses heuristics to compute multipart ETags client-side to avoid uploading or downloading files unnecessarily.
- Automatically provide Content-Type for uploads based on file extension.
See also the companion CLI tool which is meant to be a drop-in replacement for s3cmd: s3-cli.
Synopsis
Create a client
var s3 = require('s3');
var client = s3.createClient({
maxAsyncS3: 20, // this is the default
s3RetryCount: 3, // this is the default
s3RetryDelay: 1000, // this is the default
multipartUploadThreshold: 20971520, // this is the default (20 MB)
multipartUploadSize: 15728640, // this is the default (15 MB)
s3Options: {
accessKeyId: "your s3 key",
secretAccessKey: "your s3 secret",
// any other options are passed to new AWS.S3()
// See: http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/Config.html#constructor-property
},
});Create a client from existing AWS.S3 object
var s3 = require('s3');
var awsS3Client = new AWS.S3(s3Options);
var options = {
s3Client: awsS3Client,
// more options available. See API docs below.
};
var client = s3.createClient(options);Upload a file to S3
var params = {
localFile: "some/local/file",
s3Params: {
Bucket: "s3 bucket name",
Key: "some/remote/file",
// other options supported by putObject, except Body and ContentLength.
// See: http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property
},
};
var uploader = client.uploadFile(params);
uploader.on('error', function(err) {
console.error("unable to upload:", err.stack);
});
uploader.on('progress', function() {
console.log("progress", uploader.progressMd5Amount,
uploader.progressAmount, uploader.progressTotal);
});
uploader.on('end', function() {
console.log("done uploading");
});Download a file from S3
var params = {
localFile: "some/local/file",
s3Params: {
Bucket: "s3 bucket name",
Key: "some/remote/file",
// other options supported by getObject
// See: http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#getObject-property
},
};
var downloader = client.downloadFile(params);
downloader.on('error', function(err) {
console.error("unable to download:", err.stack);
});
downloader.on('progress', function() {
console.log("progress", downloader.progressAmount, downloader.progressTotal);
});
downloader.on('end', function() {
console.log("done downloading");
});Sync a directory to S3
var params = {
localDir: "some/local/dir",
deleteRemoved: true, // default false, whether to remove s3 objects
// that have no corresponding local file.
s3Params: {
Bucket: "s3 bucket name",
Prefix: "some/remote/dir/",
// other options supported by putObject, except Body and ContentLength.
// See: http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property
},
};
var uploader = client.uploadDir(params);
uploader.on('error', function(err) {
console.error("unable to sync:", err.stack);
});
uploader.on('progress', function() {
console.log("progress", uploader.progressAmount, uploader.progressTotal);
});
uploader.on('end', function() {
console.log("done uploading");
});Tips
Consider increasing the socket pool size in the
httpandhttpsglobal agents. This will improve bandwidth when usinguploadDiranddownloadDirfunctions. For example:http.globalAgent.maxSockets = https.globalAgent.maxSockets = 20;
API Documentation
s3.AWS
This contains a reference to the aws-sdk module. It is a valid use case to use both this module and the lower level aws-sdk module in tandem.
s3.createClient(options)
Creates an S3 client.
options:
s3Client- optional, an instance ofAWS.S3. Leave blank if you provides3Options.s3Options- optional. leave blank if you provides3Client.- See AWS SDK documentation for available options which are passed to
new AWS.S3(): http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/Config.html#constructor-property
- See AWS SDK documentation for available options which are passed to
maxAsyncS3- maximum number of simultaneous requests this client will ever have open to S3. defaults to20.s3RetryCount- how many times to try an S3 operation before giving up. Default 3.s3RetryDelay- how many milliseconds to wait before retrying an S3 operation. Default 1000.multipartUploadThreshold- if a file is this many bytes or greater, it will be uploaded via a multipart request. Default is 20MB. Minimum is 5MB. Maximum is 5GB.multipartUploadSize- when uploading via multipart, this is the part size. The minimum size is 5MB. The maximum size is 5GB. Default is 15MB. Note that S3 has a maximum of 10000 parts for a multipart upload, so if this value is too small, it will be ignored in favor of the minimum necessary value required to upload the file.
s3.getPublicUrl(bucket, key, [bucketLocation])
bucketS3 bucketkeyS3 keybucketLocationstring, one of these:- "" (default) - US Standard
- "eu-west-1"
- "us-west-1"
- "us-west-2"
- "ap-southeast-1"
- "ap-southeast-2"
- "ap-northeast-1"
- "sa-east-1"
You can find out your bucket location programatically by using this API: http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#getBucketLocation-property
returns a string which looks like this:
https://s3.amazonaws.com/bucket/key
or maybe this if you are not in US Standard:
https://s3-eu-west-1.amazonaws.com/bucket/key
s3.getPublicUrlHttp(bucket, key)
bucketS3 BucketkeyS3 Key
Works for any region, and returns a string which looks like this:
http://bucket.s3.amazonaws.com/key
client.uploadFile(params)
See http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property
params:
s3Params: params to pass to AWS SDKputObject.localFile: path to the file on disk you want to upload to S3.- (optional)
defaultContentType: Unless you explicitly set theContentTypeparameter ins3Params, it will be automatically set for you based on the file extension oflocalFile. If the extension is unrecognized,defaultContentTypewill be used instead. Defaults toapplication/octet-stream.
The difference between using AWS SDK putObject and this one:
- This works with files, not streams or buffers.
- If the reported MD5 upon upload completion does not match, it retries.
- If the file size is large enough, uses multipart upload to upload parts in parallel.
- Retry based on the client's retry settings.
- Progress reporting.
- Sets the
ContentTypebased on file extension if you do not provide it.
Returns an EventEmitter with these properties:
progressMd5AmountprogressAmountprogressTotal
And these events:
'error' (err)'end' (data)- emitted when the file is uploaded successfullydatais the same object that you get fromputObjectin AWS SDK
'progress'- emitted whenprogressMd5Amount,progressAmount, andprogressTotalproperties change. Note that it is possible for progress to go backwards when an upload fails and must be retried.'fileOpened' (fdSlicer)- emitted whenlocalFilehas been opened. The file is opened with the fd-slicer module because we might need to read from multiple locations in the file at the same time.fdSliceris an object for which you can callcreateReadStream(options). See the fd-slicer README for more information.'fileClosed'- emitted whenlocalFilehas been closed.
And these methods:
abort()- call this to stop the find operation.
client.downloadFile(params)
See http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#getObject-property
params:
localFile- the destination path on disk to write the s3 object intos3Params: params to pass to AWS SDKgetObject.
The difference between using AWS SDK getObject and this one:
- This works with a destination file, not a stream or a buffer.
- If the reported MD5 upon download completion does not match, it retries.
- Retry based on the client's retry settings.
- Progress reporting.
Returns an EventEmitter with these properties:
progressAmountprogressTotal
And these events:
'error' (err)'end'- emitted when the file is downloaded successfully'progress'- emitted whenprogressAmountandprogressTotalproperties change.
client.downloadBuffer(s3Params)
http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#getObject-property
s3Params: params to pass to AWS SDKgetObject.
The difference between using AWS SDK getObject and this one:
- This works with a buffer only.
- If the reported MD5 upon download completion does not match, it retries.
- Retry based on the client's retry settings.
- Progress reporting.
Returns an EventEmitter with these properties:
progressAmountprogressTotal
And these events:
'error' (err)'end' (buffer)- emitted when the file is downloaded successfully.bufferis aBuffercontaining the object data.'progress'- emitted whenprogressAmountandprogressTotalproperties change.
client.downloadStream(s3Params)
http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#getObject-property
s3Params: params to pass to AWS SDKgetObject.
The difference between using AWS SDK getObject and this one:
- This works with a stream only.
If you want retries, progress, or MD5 checking, you must code it yourself.
Returns a ReadableStream with these additional events:
'httpHeaders' (statusCode, headers)- contains the HTTP response headers and status code.
client.listObjects(params)
See http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#listObjects-property
params:
s3Params- params to pass to AWS SDKlistObjects.- (optional)
recursive-trueorfalsewhether or not you want to recurse into directories. Defaultfalse.
Note that if you set Delimiter in s3Params then you will get a list of
objects and folders in the directory you specify. You probably do not want to
set recursive to true at the same time as specifying a Delimiter because
this will cause a request per directory. If you want all objects that share a
prefix, leave the Delimiter option null or undefined.
Be sure that s3Params.Prefix ends with a trailing slash (/) unless you
are requesting the top-level listing, in which case s3Params.Prefix should
be empty string.
The difference between using AWS SDK listObjects and this one:
- Retries based on the client's retry settings.
- Supports recursive directory listing.
- Makes multiple requests if the number of objects to list is greater than 1000.
Returns an EventEmitter with these properties:
progressAmountobjectsFounddirsFound
And these events:
'error' (err)'end'- emitted when done listing and no more 'data' events will be emitted.'data' (data)- emitted when a batch of objects are found. This is the same as thedataobject in AWS SDK.'progress'- emitted whenprogressAmount,objectsFound, anddirsFoundproperties change.
And these methods:
abort()- call this to stop the find operation.
client.deleteObjects(s3Params)
See http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#deleteObjects-property
s3Params are the same.
The difference between using AWS SDK deleteObjects and this one:
- Retry based on the client's retry settings.
- Make multiple requests if the number of objects you want to delete is greater than 1000.
Returns an EventEmitter with these properties:
progressAmountprogressTotal
And these events:
'error' (err)'end'- emitted when all objects are deleted.'progress'- emitted when theprogressAmountorprogressTotalproperties change.'data' (data)- emitted when a request completes. There may be more.
client.uploadDir(params)
Syncs an entire directory to S3.
params:
localDir- source path on local file system to sync to S3s3ParamsPrefix(required)Bucket(required)
- (optional)
deleteRemoved- delete s3 objects with no corresponding local file. default false - (optional)
getS3Params- function which will be called for every file that needs to be uploaded. You can use this to skip some files. See below. - (optional)
defaultContentType: Unless you explicitly set theContentTypeparameter ins3Params, it will be automatically set for you based on the file extension oflocalFile. If the extension is unrecognized,defaultContentTypewill be used instead. Defaults toapplication/octet-stream. - (optional)
followSymlinks- Set this tofalseto ignore symlinks. Defaults totrue.
function getS3Params(localFile, stat, callback) {
// call callback like this:
var err = new Error(...); // only if there is an error
var s3Params = { // if there is no error
ContentType: getMimeType(localFile), // just an example
};
// pass `null` for `s3Params` if you want to skip uploading this file.
callback(err, s3Params);
}Returns an EventEmitter with these properties:
progressAmountprogressTotalprogressMd5AmountprogressMd5TotaldeleteAmountdeleteTotalfilesFoundobjectsFounddoneFindingFilesdoneFindingObjectsdoneMd5
And these events:
'error' (err)'end'- emitted when all files are uploaded'progress'- emitted when any of the above progress properties change.'fileUploadStart' (localFilePath, s3Key)- emitted when a file begins uploading.'fileUploadEnd' (localFilePath, s3Key)- emitted when a file successfully finishes uploading.
uploadDir works like this:
- Start listing all S3 objects for the target
Prefix. S3 guarantees returned objects to be in sorted order. - Meanwhile, recursively find all files in
localDir. - Once all local files are found, we sort them (the same way that S3 sorts).
- Next we iterate over the sorted local file list one at a time, computing MD5 sums.
- Now S3 object listing and MD5 sum computing are happening in parallel. As
each operation progresses we compare both sorted lists side-by-side,
iterating over them one at a time, uploading files whose MD5 sums don't
match the remote object (or the remote object is missing), and, if
deleteRemovedis set, deleting remote objects whose corresponding local files are missing.
client.downloadDir(params)
Syncs an entire directory from S3.
params:
localDir- destination directory on local file system to sync tos3ParamsPrefix(required)Bucket(required)
- (optional)
deleteRemoved- delete local files with no corresponding s3 object. defaultfalse - (optional)
getS3Params- function which will be called for every object that needs to be downloaded. You can use this to skip downloading some objects. See below. - (optional)
followSymlinks- Set this tofalseto ignore symlinks. Defaults totrue.
function getS3Params(localFile, s3Object, callback) {
// localFile is the destination path where the object will be written to
// s3Object is same as one element in the `Contents` array from here:
// http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#listObjects-property
// call callback like this:
var err = new Error(...); // only if there is an error
var s3Params = { // if there is no error
VersionId: "abcd", // just an example
};
// pass `null` for `s3Params` if you want to skip downloading this object.
callback(err, s3Params);
}Returns an EventEmitter with these properties:
progressAmountprogressTotalprogressMd5AmountprogressMd5TotaldeleteAmountdeleteTotalfilesFoundobjectsFounddoneFindingFilesdoneFindingObjectsdoneMd5
And these events:
'error' (err)'end'- emitted when all files are downloaded'progress'- emitted when any of the progress properties above change'fileDownloadStart' (localFilePath, s3Key)- emitted when a file begins downloading.'fileDownloadEnd' (localFilePath, s3Key)- emitted when a file successfully finishes downloading.
downloadDir works like this:
- Start listing all S3 objects for the target
Prefix. S3 guarantees returned objects to be in sorted order. - Meanwhile, recursively find all files in
localDir. - Once all local files are found, we sort them (the same way that S3 sorts).
- Next we iterate over the sorted local file list one at a time, computing MD5 sums.
- Now S3 object listing and MD5 sum computing are happening in parallel. As
each operation progresses we compare both sorted lists side-by-side,
iterating over them one at a time, downloading objects whose MD5 sums don't
match the local file (or the local file is missing), and, if
deleteRemovedis set, deleting local files whose corresponding objects are missing.
client.deleteDir(s3Params)
Deletes an entire directory on S3.
s3Params:
BucketPrefix- (optional)
MFA
Returns an EventEmitter with these properties:
progressAmountprogressTotal
And these events:
'error' (err)'end'- emitted when all objects are deleted.'progress'- emitted when theprogressAmountorprogressTotalproperties change.
deleteDir works like this:
- Start listing all objects in a bucket recursively. S3 returns 1000 objects per response.
- For each response that comes back with a list of objects in the bucket, immediately send a delete request for all of them.
client.copyObject(s3Params)
See http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#copyObject-property
s3Params are the same. Don't forget that CopySource must contain the
source bucket name as well as the source key name.
The difference between using AWS SDK copyObject and this one:
- Retry based on the client's retry settings.
Returns an EventEmitter with these events:
'error' (err)'end' (data)
client.moveObject(s3Params)
See http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#copyObject-property
s3Params are the same. Don't forget that CopySource must contain the
source bucket name as well as the source key name.
Under the hood, this uses copyObject and then deleteObjects only if the
copy succeeded.
Returns an EventEmitter with these events:
'error' (err)'copySuccess' (data)'end' (data)
Testing
S3_KEY=<valid_s3_key> S3_SECRET=<valid_s3_secret> S3_BUCKET=<valid_s3_bucket> npm test
Tests upload and download large amounts of data to and from S3. The test timeout is set to 40 seconds because Internet connectivity waries wildly.