Web Assembly (WAMR) on Unikraft

This application runs a wasm file. Follow the instructions below to set up, configure, build and run wamr.

To get started immediately, you can use Unikraft's companion command-line companion tool, kraft. Start by running the interactive installer:

curl --proto '=https' --tlsv1.2 -sSf https://get.kraftkit.sh | sudo sh

Once installed, clone this repository and run kraft build:

git clone https://github.com/unikraft/app-wamr wamr
cd wamr/
kraft build

This will guide you through an interactive build process where you can select one of the available targets (architecture/platform combinations). Otherwise, we recommend building for qemu/x86_64 like so:

kraft build --target wamr-qemu-x86_64-initrd

Once built, you can instantiate the unikernel via:

kraft run --target wamr-qemu-x86_64-initrd --initrd ./

If you don't have KVM support (such as when running inside a virtual machine), pass the -W option to kraft run to disable virtualization support:

kraft run -W --target wamr-qemu-x86_64-initrd --initrd ./

When left without the --target argument, you'll be queried for the desired target from the list.

Running it will print a "Hello, World!" message by executing the rootfs/main.wasm file.

Work with the Basic Build & Run Toolchain (Advanced)

You can set up, configure, build and run the application from grounds up, without using the companion tool kraft.

Quick Setup (aka TLDR)

For a quick setup, run the commands below. Note that you still need to install the requirements.

For building and running everything for x86_64, follow the steps below:

git clone https://github.com/unikraft/app-wamr wamr
cd wamr/
./scripts/setup.sh
wget https://raw.githubusercontent.com/unikraft/app-testing/staging/scripts/generate.py -O scripts/generate.py
chmod a+x scripts/generate.py
./scripts/generate.py
./scripts/build/make-qemu-x86_64-9pfs.sh
./scripts/run/qemu-x86_64-9pfs.sh

This will configure, build and run the main.wasm file via Wamr. You can see how to test it in the running section.

The same can be done for AArch64, by running the commands below:

git clone https://github.com/unikraft/app-wamr wamr
cd wamr/
./scripts/setup.sh
wget https://raw.githubusercontent.com/unikraft/app-testing/staging/scripts/generate.py -O scripts/generate.py
chmod a+x scripts/generate.py
./scripts/generate.py
./scripts/build/make-qemu-arm64-9pfs.sh
./scripts/run/qemu-arm64-9pfs.sh

Similar to the x86_64 build, this will start the main.wasm file via Wamr. Information about every step is detailed below.

Requirements

In order to set up, configure, build and run wamr on Unikraft, the following packages are required:

• build-essential / base-devel / @development-tools (the meta-package that includes make, gcc and other development-related packages)
• sudo
• flex
• bison
• git
• wget
• uuid-runtime
• qemu-system-x86
• qemu-kvm
• sgabios

GCC >= 8 is required to build wamr on Unikraft.

On Ubuntu/Debian or other apt-based distributions, run the following command to install the requirements:

$ apt-get install -y --no-install-recommends \
  build-essential \
  sudo \
  libncurses-dev \
  libyaml-dev \
  flex \
  bison \
  git \
  wget \
  uuid-runtime \
  qemu-kvm \
  qemu-system-x86 \
  sgabios

Set Up

The following repositories are required for wamr:

• The application repository (this repository): app-wamr
• The Unikraft core repository: unikraft
• Library repositories:
  • The wamr "library" repository: lib-wamr
  • The standard C library: lib-musl
  • The networking stack library: lib-lwip

Follow the steps below for the setup:

1. First clone the app-wamr repository in the wamr/ directory:

   git clone https://github.com/unikraft/app-wamr wamr

   Enter the wamr/ directory:

   cd wamr/
   
   ls -aF

   This will print the contents of the repository:

   Makefile  Makefile.uk  README.md  defconfigs/  kraft.yaml  rootfs/  scripts/
   

2. While inside the wamr/ directory, clone all required repositories by using the setup.sh script:

   ./scripts/setup.sh

3. Use the tree command to inspect the contents of the workdir/ directory:

   tree -F -L 2 workdir/

   The layout of the workdir/ directory should look something like this:

     workdir/
     |-- libs/
     |   |-- lwip/
     |   |-- musl/
     |   `-- wamr/
     `-- unikraft/
         |-- arch/
         |-- Config.uk
         |-- CONTRIBUTING.md
         |-- COPYING.md
         |-- include/
         |-- lib/
         |-- Makefile
         |-- Makefile.uk
         |-- plat/
         |-- README.md
         |-- support/
         `-- version.mk
   
   9 directories, 7 files
   

Scripted Building and Running

To make it easier to build, run and test different configurations, the repository provides a set of scripts that do everything required. These are scripts used for building different configurations of Duktape and for running these with all the requirements behind the scenes.

First of all, grab the generate.py script and place it in the scripts/ directory by running:

wget https://raw.githubusercontent.com/unikraft/app-testing/staging/scripts/generate.py -O scripts/generate.py
chmod a+x scripts/generate.py

Now, run the generate.py script. You must run it in the root directory of this repository:

./scripts/generate.py

The scripts (as shell scripts) are now generated in scripts/build/ and scripts/run/:

scripts/
|-- build/
|   |-- kraft-kvm-x86_64.sh*
|   |-- make-fc-arm64-initrd.sh*
|   |-- make-fc-arm64.sh*
|   |-- make-fc-x86_64-initrd.sh*
|   |-- make-fc-x86_64.sh*
|   |-- make-qemu-arm64-9pfs.sh*
|   |-- make-qemu-arm64-initrd.sh*
|   |-- make-qemu-arm64.sh*
|   |-- make-qemu-x86_64-9pfs.sh*
|   |-- make-qemu-x86_64-initrd.sh*
|   `-- make-qemu-x86_64.sh*
|-- generate.py*
|-- run/
|   |-- fc-arm64-initrd.json
|   |-- fc-arm64-initrd.sh*
|   |-- fc-arm64.json
|   |-- fc-arm64.sh*
|   |-- fc-x86_64-initrd.json
|   |-- fc-x86_64-initrd.sh*
|   |-- fc-x86_64.json
|   |-- fc-x86_64.sh*
|   |-- kraft-kvm-x86_64.sh*
|   |-- qemu-arm64-9pfs.sh*
|   |-- qemu-arm64-initrd.sh*
|   |-- qemu-arm64.sh*
|   |-- qemu-x86_64-9pfs.sh*
|   |-- qemu-x86_64-initrd.sh*
|   `-- qemu-x86_64.sh*
|-- run.yaml
`-- setup.sh*

They are shell scripts, so you can use an editor or a text viewer to check their contents:

cat scripts/run/fc-x86_64-initrd.sh

Now, invoke each script to build and run the application. A sample build and run set of commands is:

./scripts/build/make-qemu-x86_64-9pfs.sh
./scripts/run/qemu-x86_64-9pfs.sh

Note that Firecracker only works with initrd (not 9pfs). And Firecracker networking is not yet upstream.

Detailed Steps

Configure

Configuring, building and running a Unikraft application depends on our choice of platform and architecture. Currently, supported platforms are QEMU (KVM), Xen and linuxu. QEMU (KVM) is known to be working, so we focus on that.

Supported architectures are x86_64 and AArch64.

Use the corresponding the configuration files (defconfigs/*), according to your choice of platform and architecture.

QEMU x86_64

Use the defconfigs/qemu-x86_64-9pfs configuration file together with make defconfig to create the configuration file:

UK_DEFCONFIG=$(pwd)/defconfigs/qemu-x86_64-9pfs make defconfig

This results in the creation of the .config file:

ls .config
.config

The .config file will be used in the build step.

QEMU AArch64

Use the defconfigs/qemu-arm64-9pfs configuration file together with make defconfig to create the configuration file:

UK_DEFCONFIG=$(pwd)/defconfigs/qemu-arm64-9pfs make defconfig

Similar to the x86_64 configuration, this results in the creation of the .config file that will be used in the build step.

Build

Building uses as input the .config file from above, and results in a unikernel image as output. The unikernel output image, together with intermediary build files, are stored in the workdir/build/ directory.

Clean Up

Before starting a build on a different platform or architecture, you must clean up the build output. This may also be required in case of a new configuration.

Cleaning up is done with 3 possible commands:

• make clean: cleans all actual build output files (binary files, including the unikernel image)
• make properclean: removes the entire workdir/build/ directory
• make distclean: removes the entire workdir/build/ directory and the .config file

Typically, you would use make properclean to remove all build artifacts, but keep the configuration file.

QEMU x86_64

Building for QEMU x86_64 assumes you did the QEMU x86_64 configuration step above. Build the Unikraft Wamr image for QEMU x86_64 by using the command below:

make -j $(nproc)

You will see a list of all the files generated by the build system:

[...]
  LD      wamr_qemu-x86_64.dbg
  UKBI    wamr_qemu-x86_64.dbg.bootinfo
  SCSTRIP wamr_qemu-x86_64
  GZ      wamr_qemu-x86_64.gz
make[1]: Leaving directory 'wamr/workdir/unikraft'

At the end of the build command, the wamr_qemu-x86_64 unikernel image is generated. This image is to be used in the run step.

QEMU AArch64

If you had configured and build a unikernel image for another platform or architecture (such as x86_64) before, then:

1. Do a cleanup step with make properclean.

2. Configure for QEMU AAarch64, as shown above.

3. Follow the instructions below to build for QEMU AArch64.

Building for QEMU AArch64 assumes you did the QEMU AArch64 configuration step above. Build the Unikraft Wamr image for QEMU AArch64 by using the same command as for x86_64:

make -j $(nproc)

Similar to building for x86_64, you will see a list of the files generated by the build system.

[...]
  LD      wamr_qemu-arm64.dbg
  UKBI    wamr_qemu-arm64.dbg.bootinfo
  SCSTRIP wamr_qemu-arm64
  GZ      wamr_qemu-arm64.gz
make[1]: Leaving directory 'wamr/workdir/unikraft

Similarly to x86_64, at the end of the build command, the wamr_qemu-arm64 unikernel image is generated. This image is to be used in the run step.

Run

QEMU x86_64

To run the QEMU x86_64 build, use run-qemu-x86_64-9pfs.sh:

./scripts/generate.py
./scripts/run/qemu-x86_64-9pfs.sh

This will run the rootfs/main.wasm file with Wamr:

Powered by
o.   .o       _ _               __ _
Oo   Oo  ___ (_) | __ __  __ _ ' _) :_
oO   oO ' _ `| | |/ /  _)' _` | |_|  _)
oOo oOO| | | | |   (| | | (_) |  _) :_
 OoOoO ._, ._:_:_,\_._,  .__,_:_, \___)
             Prometheus 0.14.0~14b1ee3d
Hello world!
buf ptr: 0x400002b0
buf: 1234

QEMU AArch64

To run the AArch64 build, use run-qemu-aarch64-9pfs.sh:

./scripts/generate.py
./scripts/run/qemu-arm64-9pfs.sh

Same as above, this will run the rootfs/main.wasm file with Wamr.

Building and Running with initrd

The examples above use 9pfs as the filesystem interface. Clean up the previous configuration, use the initrd configuration and build the unikernel by using the commands:

./scripts/generate.py
./scripts/build/make-qemu-x86_64-initrd.sh

To run the QEMU x86_64 initrd build, use the qemu-x86_64-initrd.sh script:

./scripts/run/qemu-x86_64-initrd.sh

The commands for AArch64 are similar:

./scripts/build/make-qemu-arm64-initrd.sh
./scripts/run/qemu-arm64-initrd.sh

Building and Running with Firecracker

Firecracker is a lightweight VMM (virtual machine manager) that can be used as more efficient alternative to QEMU.

Configure and build commands are similar to a QEMU-based build with an initrd-based filesystem:

./scripts/build/make-fc-x86_64-initrd.sh

To use Firecraker, you need to download a Firecracker release. You can use the commands below to make the firecracker-x86_64 executable from release v1.4.0 available globally in the command line:

cd /tmp 
wget https://github.com/firecracker-microvm/firecracker/releases/download/v1.4.0/firecracker-v1.4.0-x86_64.tgz
tar xzf firecracker-v1.4.0-x86_64.tgz 
sudo cp release-v1.4.0-x86_64/firecracker-v1.4.0-x86_64 /usr/local/bin/firecracker-x86_64

To run a unikernel image, you need to configure a JSON file. This is the scripts/run/fc-x86_64-initrd.json file. This configuration file is uses as part of the run command:

./scripts/run/fc-x86_64-initrd.sh

Same as running with QEMU, the application will start:

Powered by
o.   .o       _ _               __ _
Oo   Oo  ___ (_) | __ __  __ _ ' _) :_
oO   oO ' _ `| | |/ /  _)' _` | |_|  _)
oOo oOO| | | | |   (| | | (_) |  _) :_
 OoOoO ._, ._:_:_,\_._,  .__,_:_, \___)
             Prometheus 0.14.0~14b1ee3d
Hello world!
buf ptr: 0x400002b0
buf: 1234