Skip to content

An abstraction for local/remote disks for node inspired by The League of Extraordinary Packages's FlySystem.


Notifications You must be signed in to change notification settings


Repository files navigation

Node Disks

An abstraction for local/remote disks for node inspired by The League of Extraordinary Packages's FlySystem.


  • Node >= 10

Getting Started

Install the package in your project:

yarn add @carimus/node-disks

Or if you're using npm:

npm install --save @carimus/node-disks


There's two way to utilize the abstract disk implementations that this library supports.

Option A: Use Disks Directly

You can create new instances of any of the exported *Disk classes directly and use their available Disk methods to perform operations.

For example (in typescript):

import { Disk, LocalDisk, S3Disk, pipeStreams } from '@carimus/node-disks';

const foo: Disk = new LocalDisk({ root: '/tmp' });
const bar: Disk = new S3Disk({ bucket: 'test' });

// Wrap everything in a self-executing async function.
(async () => {
    // Write a file to the foo disk
    await foo.write('foo.txt', 'This is a foo file');

    // Log out the contents of foo.txt

    // Stream the file from the foo disk to the bar disk as bar.txt
    const fooReadStream = await foo.createReadStream('foo.txt');
    const barWriteStream = await bar.createWriteStream('bar.txt');
    await pipeStreams(fooReadStream, barWriteStream);

    // Get a listing of the bar disk contents and store it on the foo disk.
    const s3Listing = await bar.list();
    await foo.write('s3listing.json', JSON.stringify(s3Listing, null, 2));

    // Delete the files we created
    await foo.delete('foo.txt');
    await foo.delete('s3listing.json');
    await bar.delete('bar.txt');

Option B: Use a Disk Manager

node-disks also ships with a DiskManager that you can provide a single, declarative configuration up front and then load disks by name from that config.

For example, considering the two disks in Option A below, we could have instead done:

import { DiskManager, Disk, DiskDriver } from '@carimus/node-disks';

const diskManager = new DiskManager({
    // `default` MUST be an alias to another disk. All other keys can be aliases (strings) or objects.
    default: 'foo',
    foo: {
        driver: DiskDriver.Local,
        config: {
            root: '/tmp',
    bar: {
        driver: DiskDriver.S3,
        config: {
            bucket: 'test',
    baz: 'bar', // Alias the baz disk name to the bar S3 disk.

const foo: Disk = diskManager.getDisk('foo');
const bar: Disk = diskManager.getDisk('bar');

// Use `foo` and `bar` not worrying about their implementation like in Option A.

Supported Drivers and Options


All drivers inherit from and implement the abstract Disk class and as such inherit some default base functionality and options.

Common Disk Options

Name Type Description
url string Optional; If the disk supports URLs, this is the base URL to prepend to paths
temporaryUrlExpires number Optional; If the disk supports temp URLs, how many seconds after generation do they expire? Default 1 day.
temporaryUrlFallback boolean Optional; If the disk supports URLs but not temp URLs, should it by default fallback to permanent URLs?


Driver name: 'memory' (DiskDriver.Memory)

Disk class: MemoryDisk

DiskConfig interface: DiskConfig (no extra config outside of common DiskConfig)

An in-memory disk whose contents will be forgotten when the node process ends. Each instance of the MemoryDisk has its own isolated filesystem.

Memory Disk Options

Takes no options.


Driver name: 'local' (DiskDriver.Local)

Disk class: LocalDisk

DiskConfig interface: LocalDiskConfig

A disk that uses the local filesystem.

Local Disk Options

Name Type Description
root string Required; The absolute path to thee directory where files should be stored on the local filesystem.


Driver name: 's3' (DiskDriver.S3)

Disk class: S3Disk

DiskConfig interface: S3DiskConfig

A disk that uses a remote AWS S3 bucket.

S3 Disk Options

Name Type Description
bucket string Required; The S3 bucket to use.
root string Optional; The prefix to use for storing objects in the bucket. Defaults to the root
pagingLimit number Optional; Num of max results to fetch when paging through an S3 listObjectsV2 call. Defaults to 1000, the max.
expires number Optional; Number of seconds from time of upload to set Expires and Cache-Control for putObject calls.
putParams object Optional; Additional params to merge into all putObject calls
clientConfig object Optional; Options to pass to the AWS.S3 client constructor. Can be used to pass credentials if not using env variables.
autoContentType bool Optional; Use the mime library to guess ContentType for write operations. Defaults to true


Disk Abstract Class


  • async read(path: string): Promise<Buffer> to read a file into memory
  • async createReadStream(path: string): Promise<Readable> to obtain a readable stream to a file
  • async write(path: string, contents: Buffer): Promise<void> to write to a file
  • async createReadStream(path: string): Promise<Writable> to obtain a writable stream to a file
  • async delete(path: string): Promise<void> to delete a file (not a directory)
  • async list(path: string): Promise<DiskListingObject[]> to obtain a list of objects in a directory on the disk.
  • getName(): string | null to get the name of the disk if it was created with one. The DiskManager will automatically and appropriately set this to the actual resolved name of the disk from the config.
  • getUrl(path: string): string | null to get a URL to an object if the disk supports it and is configured appropriately. If the disk doesn't support URLs, null is returned.
  • getTemporaryUrl(path: string, expires: number, fallback: boolean): string | null to get a temporary URL to an object if the disk supports it and is configured appropriately. This method by default won't fallback to generating permanent URLs but can if fallback is explicitly passed as true or if the disk is configured with temporaryUrlFallback set to true. If the disk doesn't support temporary URLs and can't fallback to permanent URLs, null is returned.
  • isTemporaryUrlValid(temporaryUrl: string, against: number | Date = boolean | null to determine if a temporary URL generated with getTemporaryUrl is valid (i.e. unexpired). Will return null if the URL can't be determined either way or if the disk does not support temporary URLs.
  • async withTempFile(path: string, execute: ((path: string) => Promise<void> | void) | null, extraOptions?: import('tmp').FileOptions): Promise<string> to stream the contents of a file from the disk to a temporary file on the local filesystem for performing operations that are easier (or more performant, etc.) to do with local data on the disk as opposed to in memory (e.g.
    • The caller can pass an async execute callback which will get a string path to the temp file that contains the disk file's contents. Once execute returns/resolves, the file will be automatically deleted. If an execute callback is not provided, the function will resolve with the path to the temp file. IMPORTANT: it's the caller's responsibility using this approach to unlink the file when they're done with it.
    • This functionality is achieved using tmp. You can pass any additional FileOptions through to tmp (i.e. prefix) using the third parameter extraOptions.

MemoryDisk Class (extends Disk)


  • constructor(config: MemoryDiskConfig, name?: string) to create the disk.

LocalDisk Class (extends Disk)


  • constructor(config: LocalDiskConfig, name?: string) to create the disk.

S3Disk Class (extends Disk)


  • constructor(config: S3DiskConfig, name?: string, s3Client?: AWS.S3) to create the disk, optionally taking a pre-initialized S3 client instead of creating a new one.


  • constructor(config: DiskManagerConfig) create the disk manager with a map of disk names to their specification object containing at least a driver property and then additionally a config property containing whatever required config options that specific driver needs. Or a string, which is treated as an alias for another disk in the DiskManagerConfig
  • async getDisk(name: string, options: GetDiskOptions): Disk to get a disk by name. Some disks require runtime options that aren't optimal to pass through config. Those are provided in the second argument here.

DiskListingObject Interface


  • name: the name of the file or directory
  • type: the type (file or directory), see DiskObjectType

DiskObjectType Enum


Indicates the type of an object on the disk.

  • DiskObjectType.File: a file
  • DiskObjectType.Directory: a directory


This library also exports some helper methods:

  • async pipeStreams(readable: Readable, writable: Writable): Promise<string> pipes a readable stream into a writable stream and waits until it completes. It will reject if the pipe stream emits an error and will otherwise resolve with the name of the event that the stream closed with (i.e. 'close' or 'finish').
  • async streamToBuffer(stream: Readable): Promise<Buffer> pipes a readable stream into a single buffer. Rejects if the stream emits an error.


  • Make the MemoryDisk test generic to run on any Disk and figure out how to run it safely with LocalDisk and S3Disk:
    • S3Disk: credentials and bucket from environment with cleanup afterEach and don't fail if env variables aren't there.
    • LocalDisk: just randomly generate a path to a tmp directory that doesn't exist in beforeEach and use that as the disk root and rimraf it in afterEach
  • Improve tests to cover niche cases like:
    • Readable stream passed to MemoryDisk/LocalDisk
    • Properly handled symlinks in directory listings for MemoryDisk/LocalDisk
    • Proper errors from bad permissions for MemoryDisk/LocalDisk
    • Multiple writes to the same file do truncate
    • Listings always include directories first
  • Wrap all unknown errors in an UnknownDiskError (maybe using VError?)
  • Ensure that when memfs is used, we always use the posix path module even on a win32 host FS (or otherwise verify that on win32, memfs uses win32 paths).
  • Proxy read and write streams so that errors emitted on streams can be wrapped
  • Upgrade CodedError to also contain a reference to the original system/driver error
  • LocalDisk config setting to filter directory listings by only accessible files/directories.
  • Support additional basic filesystem operations:
    • Copy
    • Move
    • Delete many (globs??)
    • Delete directories (rimraf)
    • Support force delete option for not failing when file isn't found and does rimraf for directories.


This project is based on the carimus-node-ts-package-template. Check out the README and docs there for more up to date information on the development process and tools available.


An abstraction for local/remote disks for node inspired by The League of Extraordinary Packages's FlySystem.