jswasi-rootfs

Copyright (c) 2023-2026 Antmicro

This repository contains a collection of makefiles and patches that allow to build complete jswasi distributions for browser usage.

Prerequisites

To install prerequisites on Debian, use:

apt-get install git wget zip autoconf automake clang libclang-dev make build-essential node-typescript nodejs gettext-base unzip esbuild libtool curl cmake ninja-build pkg-config libssl-dev golang

Make sure you have rustup installed. You will also need at least version 1.21 of go, for installation instructions, see https://go.dev/doc/install.

Building

To build the rootfs along with the index, run:

make

or

make build

Selective Builds

If you only want to build specific packages, use the PACKAGES variable. For example, to include only coreutils, wasibox, and wash:

make PACKAGES="coreutils wasibox wash" build

Note: If a package has dependencies not listed in PACKAGES, those dependencies will still be built to ensure a valid rootfs.

Cleaning

The project provides granular control over cleaning build artifacts.

Package Cleanup

You can clean artifacts for specific packages using the same PACKAGES variable:

# Clean only specific packages
make PACKAGES="coreutils wash" clean

# Clean all packages (default behavior)
make clean

Workspace Cleanup

To wipe the entire workspace including the rootfs and dist files:

make clean_all

Specific Clean Targets

The following targets allow you to clean specific stages of the build process:

Target	Description
clean_build	Removes the work/build directory (all package build trees).
clean_rootfs	Removes the work/rootfs directory.
clean_resources	Removes the work/dist/resources directory.
clean_dist	Removes the entire work/dist directory.

Running

To run the jswasi instance, you need to serve the work/dist directory over HTTP.

Using the Make wrapper

The most convenient way is to use the provided wrapper:

make run_server

By default, this runs on port 8000. You can override it with make run_server HTTP_PORT=9000.

Manual method

Alternatively, you can use any static HTTP server. For example, using Python:

cd work/dist
python3 -m http.server 8000

Tips:

• To clean old jswasi data use purge command in jswasi terminal and refresh the page (Ctrl+Shift+F5 = hard-reload).
• To update jswasi service worker, go to: DevTools > Application > Service workers > Unregister and refresh the page.

Using alternate sources

jswasi-rootfs supports replacing package source URLs with alternate ones using ALTERNATE_URL_DEFAULT environment variable. If set, the URL pattern in this variable will be used in all packages. In case it doesn't return a successful response, the default URL is used as a fallback. In the ALTERNATE_URL_DEFAULT variable, the %VERSION, %REPO and %OWNER substrings are replaced with the respective metadata from each package.