readme.md

Substrate Validator Set

Fork from https://github.com/gautamdhameja/substrate-validator-set commit hash: f83f1000c298c376ab180787eb73d0a0fdb740e0

Code changes are in diff.patch

A Substrate pallet to add/remove validators using extrinsics, in Substrate-based PoA networks.

Note: Current build is compatible with Substrate v3.0.0 release.

Demo

To see this pallet in action in a Substrate runtime, watch this video - https://www.youtube.com/watch?v=lIYxE-tOAdw

Setup with Substrate Node Template

• Add the module's dependency in the Cargo.toml of your runtime directory. Make sure to enter the correct path or git url of the pallet as per your setup.

validatorset = { 
  version = "3.0.0", 
  package = "substrate-validator-set", 
  git = "https://github.com/threefoldtech/tfchain_pallets", 
  default-features = false
  branch = "development"
}
pallet-session = { default-features = false, version = '3.0.0' }
...
std = [
    ...
    'validatorset/std',
    'sp-session/std',
]

• Make sure that you also have the Substrate session pallet as part of your runtime. This is because the validator-set pallet is based on the session pallet.

• Import OpaqueKeys in your runtime/src/lib.rs.

use sp_runtime::traits::{
	AccountIdLookup, BlakeTwo256, Block as BlockT, Verify, IdentifyAccount, NumberFor, OpaqueKeys
};

• Declare the pallet in your runtime/src/lib.rs.

impl validatorset::Config for Runtime {
	type Event = Event;
}

• Also, declare the session pallet in your runtime/src/lib.rs. The type configuration of session pallet would depend on the ValidatorSet pallet as shown below.

impl pallet_session::Config for Runtime {
	type SessionHandler = <opaque::SessionKeys as OpaqueKeys>::KeyTypeIdProviders;
	type ShouldEndSession = ValidatorSet;
	type SessionManager = ValidatorSet;
	type Event = Event;
	type Keys = opaque::SessionKeys;
	type NextSessionRotation = ValidatorSet;
	type ValidatorId = <Self as frame_system::Config>::AccountId;
	type ValidatorIdOf = validatorset::ValidatorOf<Self>;
	type DisabledValidatorsThreshold = ();
	type WeightInfo = ();
}

• Add both session and validatorset pallets in construct_runtime macro. Make sure to add them before Aura and Grandpa pallets and after Balances.

construct_runtime!(
	pub enum Runtime
	{
		...
    	Balances: pallet_balances::{Module, Call, Storage, Config<T>, Event<T>},
		Session: pallet_session::{Module, Call, Storage, Event, Config<T>},
		ValidatorSet: validatorset::{Module, Call, Storage, Event<T>, Config<T>},
		Aura: aura::{Module, Config<T>, Inherent(Timestamp)},
		Grandpa: grandpa::{Module, Call, Storage, Config, Event},
        ...
        ...
	}
);

• Add genesis config in the chain_spec.rs file for session and validatorset pallets, and update it for Aura and Grandpa pallets. Because the validators are provided by the session pallet, we do not initialize them explicitly for Aura and Grandpa pallets. Order is important, notice that pallet_session is declared after pallet_balances since it depends on it (session accounts should have some balance).

fn testnet_genesis(initial_authorities: Vec<(AccountId, AuraId, GrandpaId)>,
	root_key: AccountId,
	endowed_accounts: Vec<AccountId>,
	_enable_println: bool) -> GenesisConfig {
	GenesisConfig {
		...,
    pallet_balances: Some(BalancesConfig {
			balances: endowed_accounts.iter().cloned().map(|k|(k, 1 << 60)).collect(),
		}),
		validatorset: Some(ValidatorSetConfig {
			validators: initial_authorities.iter().map(|x| x.0.clone()).collect::<Vec<_>>(),
		}),
		pallet_session: Some(SessionConfig {
			keys: initial_authorities.iter().map(|x| {
				(x.0.clone(), x.0.clone(), session_keys(x.1.clone(), x.2.clone()))
			}).collect::<Vec<_>>(),
		}),
		aura: Some(AuraConfig {
			authorities: vec![],
		}),
		grandpa: Some(GrandpaConfig {
			authorities: vec![],
		}),
	}
}

• Make sure you have the same number and order of session keys for your runtime. First in runtime/src/lib.rs:

pub struct SessionKeys {
	pub aura: Aura,
	pub grandpa: Grandpa,
}

• And then in src/chain_spec.rs:

fn session_keys(
	aura: AuraId,
	grandpa: GrandpaId,
) -> SessionKeys {
	SessionKeys { aura, grandpa }
}

pub fn authority_keys_from_seed(seed: &str) -> (
	AccountId,
	AuraId,
	GrandpaId
) {
	(
		get_account_id_from_seed::<sr25519::Public>(seed),
		get_from_seed::<AuraId>(seed),
		get_from_seed::<GrandpaId>(seed)
	)
}

• cargo build --release and then cargo run --release -- --dev

Sample

The usage of this pallet are demonstrated in the Substrate permissioning sample.

Additional Types for Polkadot JS Apps/API

{
  "Keys": "SessionKeys2"
}

Disclaimer

This code not audited and reviewed for production use cases. You can expect bugs and security vulnerabilities. Do not use it as-is in real applications.