Installation

Setting up the environment

Before diving right into writing code, you need to install some tooling in order to compile your contract. CosmWasm is luckily rather self-contained and therefore needs little external tooling to compile.
Our only external dependency is Rust, which you need to install for your platform.

💡 Tip

We recommend installing Rust using the official rustup installer. This makes it easy to stay on the most recent Rust version and to install compiler targets.

💡 Tip

For production builds you probably also want to install Docker, too.
This is because we offer the CosmWasm Optimizing Compiler, which uses a Docker image to build the smallest contract possible in a deterministic fashion.

Additional information about the Optimizing Compiler

Please note that this image is intended for reproducible production builds. It is not optimized for development or in general environments where you want to iterate quickly. The builder is optimizing for size, not compilation speed. If you want to slim down your contract for development, you can do so by tweaking your Cargo profile.

[profile.dev]
lto = "thin"
strip = true

If you want to build with native tools, you might miss out on determinism, but you can still build your contract into a small size like so:

RUSTFLAGS="-C link-arg=-s" cargo build --release --lib --target=wasm32-unknown-unknown
wasm-opt -Os --signext-lowering "target/wasm32-unknown-unknown/release/my-contract.wasm" -o "artifacts/my-contract.wasm"

(Note: Replace my-contract with the name of your contract. You also need wasm-opt installed, which is part of the binaryen project.)

After installing Rust, you need to add the WebAssembly target. This is needed so Rust knows how to build your code to WebAssembly.

To install the target using rustup, run the following command:

$ rustup target add wasm32-unknown-unknown

Perfect!

Now that we set up the foundation we just need two more tools:

1. cargo-generate
2. cargo-run-script (this is required to later optimize your contract for production)

To install those, run the following commands:

$ cargo install cargo-generate --features vendored-openssl
$ cargo install cargo-run-script

Setting up the contract

Now that the environment is all done, let's create the project!

Luckily you don't need to start from scratch, we already took care of the most tedious parts of setting up a new project in form of a template!

In order to generate a fresh project, run this command and off we go:

$ cargo generate --git https://github.com/CosmWasm/cw-template.git --name PROJECT_NAME

Now you should have a ready contract project in a new folder called PROJECT_NAME (or whatever you changed it to).