> ## Documentation Index
> Fetch the complete documentation index at: https://docs.optimism.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Registry

[`kona-registry`][sc] is a `no_std` crate that exports rust type definitions for chains
in the [`superchain-registry`][osr]. These are lazily evaluated statics that provide
`ChainConfig`s, `RollupConfig`s, and `Chain` objects for all chains with static definitions
in the [`superchain-registry`][osr].

Since it reads static files to read configurations for various chains into instantiated
objects, the [`kona-registry`][sc] crate requires [`serde`][serde] as a dependency.

There are three core statics exposed by the [`kona-registry`][sc].

* `CHAINS`: A list of chain objects containing the superchain metadata for this chain.
* `OPCHAINS`: A map from chain id to `ChainConfig`.
* `ROLLUP_CONFIGS`: A map from chain id to `RollupConfig`.

[`kona-registry`][sc] exports the *complete* list of chains within the superchain, as well as each
chain's `RollupConfig`s and `ChainConfig`s.

### Usage

Add the following to your `Cargo.toml`.

```toml theme={null}
[dependencies]
kona-registry = "0.1.0"
```

To make `kona-registry` `no_std`, toggle `default-features` off like so.

```toml theme={null}
[dependencies]
kona-registry = { version = "0.1.0", default-features = false }
```

Below demonstrates getting the `RollupConfig` for OP Mainnet (Chain ID `10`).

```rust theme={null}
use kona_registry::ROLLUP_CONFIGS;

let op_chain_id = 10;
let op_rollup_config = ROLLUP_CONFIGS.get(&op_chain_id);
println!("OP Mainnet Rollup Config: {:?}", op_rollup_config);
```

A mapping from chain id to `ChainConfig` is also available.

```rust theme={null}
use kona_registry::OPCHAINS;

let op_chain_id = 10;
let op_chain_config = OPCHAINS.get(&op_chain_id);
println!("OP Mainnet Chain Config: {:?}", op_chain_config);
```

[serde]: https://crates.io/crates/serde

[alloy]: https://github.com/alloy-rs/alloy

[op-alloy]: https://github.com/ethereum-optimism/optimism/tree/develop/rust/op-alloy

[op-superchain]: https://docs.optimism.io/stack/explainer

[osr]: https://github.com/ethereum-optimism/superchain-registry

[s]: #TODO

[sc]: https://crates.io/crates/kona-registry

[g]: https://crates.io/crates/kona-genesis

[chains]: https://docs.rs/kona-registry/latest/kona_registry/struct.CHAINS.html

[opchains]: https://docs.rs/kona-registry/latest/kona_registry/struct.OPCHAINS.html

[rollups]: https://docs.rs/kona-registry/latest/kona_registry/struct.ROLLUP_CONFIGS.html