Smart Rollup Kernel Gallery

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The kernel gallery is a direcory of examples to help you get started writing your own WASM kernels for Tezos Smart Rollups.

This repository is intended as companion to the docs on developing your wasm kernel. Additionally, it showcases simple end-to-end rollup applications, demonstrating how you can use rollups in your DApps.

We recommend going through examples in order:

• 00_debug_kernel: shows how to debug messages and read from the shared inbox.
• 01_storage_kernel: shows how to read and write to the kernel's persistent storage.
• 02_reboot_kernel: shows how to mark a kernel reboot and discusses kernel control flow.
• 03_inbox_kernel: shows how to read from the shared inbox.
• 04_filtering_kernel: shows how to filter messages coming from the shared inbox.
• 05_outbox_kernel: shows how to write messages to the outbox to communicate back to the L1.
• 06_counter_kernel: a larger example combining the above elements into a simple counter application.
• 09_tzwitter_app: A full fledged rollup DApp for social media, combining an L1 smart contract, rollup kernel, React+Typescript frontend, and deployment script.

Each kernel directory includes a README.md that demonstrates how to test the kernel with the octez-smart-rollup-wasm-debugger against a set of inputs and commands. The expected outputs are included in the README and checked in CI with MDX.

Setup

To build the kernels, you will need the Rust toolchain with WASM support installed, detailed below.

To run the octez-smart-rollup-wasm-debugger, you will need to install it from OPAM.

Alternatively, Nix users can activate a shell with the required dependencies with nix develop.

Setup Rust

(Mac users, don't miss the section for you further down!)

The suggested Rust version is 1.66.0.

You can install from scratch

# [install rust]
wget https://sh.rustup.rs/rustup-init.sh
chmod +x rustup-init.sh
./rustup-init.sh --profile minimal --default-toolchain 1.66.0 -y
# [source cargo]
. $HOME/.cargo/env

or, you can use rustup instead,

rustup update 1.66.0
rustup override set 1.66.0-<channel_full_name>op
rustup toolchain install 1.66.0

More details of install Rust can be found at: https://www.rust-lang.org/tools/install.

Setup WASM

We need to add wasm32-unknown-unknown to be a possible target of Rust:

rustup target add wasm32-unknown-unknown

Additional setup for Mac

The Apple clang compiler installed by default does not support the wasm32 target (check with clang --print-targets). You need to install a version which does, such as the one available through Homebrew:

brew install llvm

You also need to add this version at the beginning of your PATH. For instance, on an Apple Silicon Mac, this can be done using:

export PATH="/opt/homebrew/opt/llvm/bin/:$PATH"

If you installed clang via Homebrew, you can obtain the correct path using brew --prefix llvm.

In addition, you might also need to manually set the following environment variables, where LLVM_PATH is the same path as above:

export AR="${LLVM_PATH}/bin/llvm-ar"
export CC="${LLVM_PATH}/bin/clang"

Build the WASM kernels

You can build all the kernels with Cargo. In order to build the 09_tzwitter_app kernel you also need to set this environment variable (the value itself is not important).

export TZWITTER_L1_CONTRACT="KT1..."
cargo build --release --target wasm32-unknown-unknown

Alternatively, you can build using cargo-make:

cargo make wasm

Strip the generated WASM

The size of generated wasm file might be large, but WebAssembly Binary Toolkit (wabt) provides a tool, wasm-strip, to strip down the size of our wasm kernel.

Notice that, you need to make sure you have installed wabt with your system package manager; and, wasm-strip will directly edit the wasm file, so you might want to backup your wasm file.

wasm-strip target/wasm32-unknown-unknown/release/<name>_kernel.wasm

Tests

Each kernel comes with tests and tests of the README, defined as cargo-make tasks. You can install cargo-make like so:

cargo install cargo-make

Octez Smart Rollup WASM Debugger

The Octez software system includes an interactive debugger for Smart Rollup kernels, documented here. Each kernel's README includes examples how to use it.

Deployment

Refer to the docs. Additionally, you can look at an example deployment script in ./09_tzwitter_app/deploy.sh.