CosmWasm

Web Assembly Smart Contracts for the Cosmos SDK

This repo provides a useful functionality to build smart contracts that are compatible with Cosmos SDK runtime, currently being developed.

Creating a Smart Contract

You can see some examples of contracts under the contracts directory. We aim to provide more tooling to help this process, but for now it is a manual step. You can do this in the contracts directory if you are working in this project, or wherever you want in your own project.

You can follow more instructions on how to configure a library for wasm

API entry points

Web Assembly contracts are basically black boxes. The have no default entry points, and no access to the outside world by default. To make them useful, we need to add a few elements.

We explain how to create entry points in general for rust-wasm tooling, as well as document the required API for CosmWasm contracts

Implementing the Smart Contract

TODO Explain what is needed

TODO Link to sample implementation

Testing the Smart Contract (rust)

For quick unit tests and useful error messages, it is often helpful to compile the code using native build system and then test all code except for the extern "C" functions (which should just be small wrappers around the real logic).

If you have non-trivial logic in the contract, please write tests using rust's standard tooling. If you run cargo test, it will compile into native code using the debug profile, and you get the normal test environment you know and love. Notably, you can add plenty of requirements to [dev-dependencies] in Cargo.toml and they will be available for your testing joy. As long as they are only used in #[cfg(test)] blocks, they will never make it into the (release) Wasm builds and have no overhead on the production artifact.

TODO Add some tests to sample and link them here

Testing the Smart Contract (wasm)

You may also want to ensure the compiled contract interacts with the environment properly. To do so, you will want to create a canonical release build of the <contract>.wasm file and then write tests in go with a some tooling in the cosmwasm/cosmos-sdk repo (TODO)

Benchmarking

You may want to compare how long the contract takes to run inside the Wasm VM compared to in native rust code, especially for computationally intensive code, like hashing or signature verification.

TODO add instructions and maybe some Dockerfile tooling