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Overview

version

cargo-contract is a CLI tool which helps you set up and manage WebAssembly smart contracts written with ink!. You can find it here on GitHub and here on crates.io.

The tool has a number of handy capabilities:

cargo-contract 0.8.0Utilities to develop Wasm smart contracts.
USAGE:    cargo contract <SUBCOMMAND>
OPTIONS:    -h, --help       Prints help information    -V, --version    Prints version information
SUBCOMMANDS:    new                  Setup and create a new smart contract project    build                Compiles the contract, generates metadata, bundles both together in a '.contract' file    check                Check that the code builds as Wasm; does not output any build artifact to the top level `target/` directory    test                 Test the smart contract off-chain    deploy               Upload the smart contract code to the chain    instantiate          Instantiate a deployed smart contract    help                 Prints this message or the help of the given subcommand(s)

Installation#

As a pre-requisite for the tool you need to install the binaryen package, which is used to optimize the WebAssembly bytecode of the contract.

Many package managers have it available nowadays โ€’ e.g. it's a package for Debian/Ubuntu, Homebrew and Arch Linux.

After you've installed the package execute:

cargo install cargo-contract --vers ^0.14 --force --locked

Use the --force to ensure you are updated to the most recent cargo-contract version.

You can then use cargo contract --help to start exploring the commands made available to you.

Usage#

In order to initialize a new ink! project you can use:

cargo contract new flipper

This will create a folder flipper in your work directory. The folder contains a scaffold Cargo.toml and a lib.rs, which both contain the necessary building blocks for using ink!.

The lib.rs contains our hello world contract โ€’ the Flipper, which we explain in the next section.

In order to build the contract just execute these commands in the flipper folder:

cargo contract build

As a result you'll get the file target/flipper.contract. It's a JSON which bundles the contract's metadata and its Wasm blob. This file needs to be used when deploying the contract. You additionally get the individual target/flipper.wasm and target/metadata.json in the folder as well.