Crate sc_chain_spec

Expand description

Substrate chain configurations.

This crate contains structs and utilities to declare a runtime-specific configuration file (a.k.a chain spec).

Basic chain spec type containing all required parameters is GenericChainSpec. It can be extended with additional options that contain configuration specific to your chain. Usually the extension is going to be an amalgamate of types exposed by Substrate core modules. To allow the core modules to retrieve their configuration from your extension you should use ChainSpecExtension macro exposed by this crate.

use std::collections::HashMap;
use sc_chain_spec::{GenericChainSpec, ChainSpecExtension};

#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecExtension)]
pub struct MyExtension {
	pub known_blocks: HashMap<u64, String>,
}

pub type MyChainSpec<G> = GenericChainSpec<G, MyExtension>;

Some parameters may require different values depending on the current blockchain height (a.k.a. forks). You can use ChainSpecGroup macro and provided Forks structure to put such parameters to your chain spec. This will allow to override a single parameter starting at specific block number.

use sc_chain_spec::{Forks, ChainSpecGroup, ChainSpecExtension, GenericChainSpec};

#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecGroup)]
pub struct ClientParams {
	max_block_size: usize,
	max_extrinsic_size: usize,
}

#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecGroup)]
pub struct PoolParams {
	max_transaction_size: usize,
}

#[derive(Clone, Debug, serde::Serialize, serde::Deserialize, ChainSpecGroup, ChainSpecExtension)]
pub struct Extension {
	pub client: ClientParams,
	pub pool: PoolParams,
}

pub type BlockNumber = u64;

/// A chain spec supporting forkable `ClientParams`.
pub type MyChainSpec1<G> = GenericChainSpec<G, Forks<BlockNumber, ClientParams>>;

/// A chain spec supporting forkable `Extension`.
pub type MyChainSpec2<G> = GenericChainSpec<G, Forks<BlockNumber, Extension>>;

It’s also possible to have a set of parameters that is allowed to change with block numbers (i.e. is forkable), and another set that is not subject to changes. This is also possible by declaring an extension that contains Forks within it.

use serde::{Serialize, Deserialize};
use sc_chain_spec::{Forks, GenericChainSpec, ChainSpecGroup, ChainSpecExtension};

#[derive(Clone, Debug, Serialize, Deserialize, ChainSpecGroup)]
pub struct ClientParams {
	max_block_size: usize,
	max_extrinsic_size: usize,
}

#[derive(Clone, Debug, Serialize, Deserialize, ChainSpecGroup)]
pub struct PoolParams {
	max_transaction_size: usize,
}

#[derive(Clone, Debug, Serialize, Deserialize, ChainSpecExtension)]
pub struct Extension {
	pub client: ClientParams,
	#[forks]
	pub pool: Forks<u64, PoolParams>,
}

pub type MyChainSpec<G> = GenericChainSpec<G, Extension>;