A static filesystem to bundle and read files using Node.js

Usage no npm install needed!

<script type="module">
  import elasticStaticFs from 'https://cdn.skypack.dev/@elastic/static-fs';



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A static filesystem to bundle multiple files into one that are able to be read by Node.js through require or the fs module.


There are a lot of use cases which require shipping node_modules along with the distribution in order to achieve a zero install workflow for our end users. Given the nature of node_modules, this directory ends up containing a magnitude of files resulting in a degraded experience, especially on Windows environments (bad performance unzipping, bad performance through an installer, max file path length, etc).

That was the first motivation and the main use case for the static filesystem: allow to bundle all the files from the node_modules during the build process into a single file and then, at runtime, force node to first look into that statically generated filesystem when searching for a file and only look in the real filesystem in case the file is not found on the static one.

While the main use case is the above there could be others like for example shipping almost every product file in a statically generated filesystem so we can make the product structure simple and transparent for the end user. The only thing to keep in mind is that tool was designed to be used during a build process under certain assumptions.


  • Pack multiple files into a single one called static filesystem that would mount relatively to the parent directory where it is generated

  • Patches require, fs, process and child_process to be able to read from the static filesystem

  • Run multiple static filesystem per application

  • One single build step tool that works out of the box

Getting Started

Remember, that this is a development tool intended to be used during your build process, so install it as development dependency and run it as a final step once your build produce the raw build artifacts.


npm install --save-dev static-fs


Generate a static filesystem volume

// example_build_step.js

const { generateStaticFsVolume } = require('static-fs');
const { resolve } = require('path');

// one example of a dependency to delete files in bulk, you can use any other
const del = require('del');

(async () => {
  const mountRoot = resolve('.'), 
    folderToAdd = resolve('node_modules'),
    entryPoint = resolve('index.js');
  // Generate a static filesystem volume
  const addedFiles = await generateStaticFsVolume(
    //, [] -> exclusions are optional and equal to [] by default
  // Delete all the files bundled into the static filesystem volume
  await del(addedFiles, { force: true });

Run your app

Just run node index.js (which was the entryPoint we assume for that example) in the root of your distributable app folder and everything should work.


async generateStaticFsVolume(mountRootDir, foldersToAdd, appEntryPointsToPatch, exclusions)

An async function that would take care of generating the static filesystem considering that the root path to mount it would be mountRootDir, the content would be created according foldersToAdd, your application entry points would be automatically patched according appEntryPointsToPatch so node can read from the generated static filesystem, and any path (folder or file) listed on exclusions would be discarded.

NOTE: After running that function a folder called .static_fs would be created inside mountRootDir with static_fs_volume.sfsv, static_fs_index.json, static_fs_manifest.json and static_fs_runtime.js.


  • mountRootDir: string: Path for the root path of the contained files into that static filesystem instance

  • foldersToAdd: string[]: List of paths of folders containing the files to bundle inside that static filesystem instance. Could not be the same as mountRootDir.

  • appEntryPointsToPatch: string[]: List of paths for the application entry points to be patched in order to read from the static filesystem.

  • exclusions: string[] = []: List of paths that would explicit not be included by the static filesystem during the generation phase. The paths on this list could be a folder or a single file and they should be absolute resolved against mountRootDir otherwise the function would throw an error. In case the path is a folder, the entire folder and children would be also excluded.


An string[] containing the paths of each file and base folder that was added into this static filesystem instance.

Known Limitations

A little set of things are not supported by the static filesystem. They can be summarised in the following list:

  • .node native modules files are not supported inside the static filesystem. They will be excluded during the generation phase and are expected to be present in the original location on the real filesystem.

  • Like the above mentioned .node files, every other platform-specific files that requires to be compiled, processed or any other changing operation during runtime are not supported inside the static filesystem. As they won't be excluded automatically, they should not be included inside the static filesystem during the generation phase.

  • While this is more a design choice than a limitation we choose to list it here: any write operation is not supported against the static filesystem during runtime. It would mimic the file state at the time it was generated. In case a write operation is requested using write flags through a method that supports it like open or createReadStream an error will be thrown. If the write operation is requested through any other write only method the file will be written at the given path and the Static-Fs will start returning the content of that file instead of the one inside the respective volume which previously have the file bundled.

Let us know if you found other unknown limitations opening an issue.


If you would like to contribute, please read CONTRIBUTING.




Read the FAQ for details.


Our thanks can be read at THANKS.