file-sink-s3

File Sink

A slim abstraction over s3 to make it look like a file system.

Why

I want to use something else I wrote, FileSink, to abstract away just a little bit of the file system interface. I want callers to be able to read and write "files" without needing to know where, specifically, on disk they're writing to, or even what they're really writing to. It could be a file system, http, AWS S3, indexeddb, mongodb, or whatever. The caller shouldn't need to know how to connect to the underlying resource, how to encrypt/decrypt, or anything more than the relative path.

This provides node js access to s3 as a file system.

Install

npm install file-sink-s3

Selected Methods Summary

• read(path) - Reads file info, returns promise resolving to buffer
• readStream(path) - Reads file info as utf-8 text stream
• write(path, data) - Where data is a string, Buffer, TypedArray or DataView. Lots of options for writing partial data/files as well. Returns promise.
• rm(path) - removes file or directory (recursive by default), returns promise
• mkdir(path) - makes directory, returns promise
• getFullFileInfo(path) - returns a promise with info about a file or directory. See format below.
• createHash(path) - A promise with the has value of the file data (sha512 by default)
• findPaths(options) - A bit like find, allows searching for files and directories by name
• find - Like findPaths, but instead of a promise it returns an EventEmitter which emits data and done events. Each data event has a file info object.

Use

import FileSinkS3 from "file-sink-s3"

let sink = new FileSinkS3({
	bucket: 'file-sink-s3-test-1'
	, prefix: 'starting/point/'
	, connection: {
		region: 'us-east-1'
		, credentials: {
			accessKeyId: 'public_key'
			, secretAccessKey: 'secret_key'
		}
	}
})


// read my-file.txt
tempSink.read('my-file.txt', function(err, data) {
	console.log(data.toString())
})

let data = await tempSink.read('my-file.txt')

// read my-file.txt
let data = tempSink.readSync('my-file.txt')
// throws error if path does not exist or some other problem happens

// write to my-file.txt
tempSink.write('my-file.txt', 'Hello, World!', function(err) {
	// log error if exists
})

try {
	await tempSink.write('my-file.txt')
}
catch(err) {
	// log error
}


// read the info for a file like mod time
let info = await tempSink.getFullFileInfo('my-file.txt')
console.log(info.stat.mtime)

// find the names of the children of a directory

let dirInfo = await tempSink.getFullFileInfo('.')
for(let child of dirInfo.children) {
	console.log((child.directory ? '(d) ': "") + child.name)
}

getFullFileInfo Data Format

Roughly, where children contains objects like this, but without the children attribute.

{
  name: 'testdir',
  parent: 'top-dir/test-data',
  stat: Stats {
    size: 4096,
    mtimeMs: 1701114609826.992,
    mtime: 2023-11-27T19:50:09.827Z
  },
  directory: true,
  relPath: 'testdir',
  accessUrl: 'https://file-sink-s3-test-1.s3.amazonaws.com/top-dir/test-data/testdir'
  children: []
}