Voluntary council

This article provides a description of "voluntary council", as a form of governance model for decentralized blockchains. It ensures both that users have choices whether to follow a hard fork or not, and that the whole method is fully automated, without worries about non-scalable human process.

Voluntary council is the planned governance model for Solri and Kulupu. This governance model also works best in a Substrate-based blockchain. Also note that the focus of this article is to provide a general framework for implementing voluntary council, rather than specific descriptions of particular council modules.

Sudo inherents

Those are extrinsics that can be included in a block. They are always rejected by default. The client can configure whitelists to allow specific sudo inherents to be included.

An example of the sudo inherent is Kulupu’s anyupgrade module. The module configures extrinsic any and any_as as inherents, and then by default rejects them. A specific ProvideInherentData is then used to customize and whitelist particular upgrades that the user wants to config as valid.

Instead of simple whitelisting, a more sophisticated sudo inherent implementation would be tight with a particular council, which we will explain in the next section. This method avoids the need for users to manually select feature upgrades every time, while in the mean time, still makes end users the ultimate decider.

By using WebAssembly/RISC-V as the runtime, end users can take their own pace to upgrade clients as frequently or seldomly as they see fit, while still be able to sync with the network at any time.

Weighted rejection

When rejecting a block due to sudo inherent, the client can choose to not fully reject the block, but accept the block, and set its weight to maximum negative value. This allows all branches of feature upgrades to technically stay in the same blockchain. If the end user changes mind and later decide to follow a different feature upgrade branch, the client can simply do a reorg, as long as the state of the range of the reorg still exists.

Council modules

Councils are arrangers of feature upgrades. They are normal contracts, for example, resides in pallet-contracts or pallet-evm. Councils can be simply human process (such as multi-sig contracts), voting process (such as coin voting or miner voting), or any other programmable process. The council must emit the following interface:

trait Council {
  fn upgrades() -> Option<(NumberFor<Block>, Vec<Extrinsic>)>;
}

Council::upgrades method should not emit any state changes. It returns the sudo inherents that it expects to exist in a proceeding block, as specified by the number.

Upon end user starts a new client, it will prompt to select a council. The client will then track that particular council contract for feature upgrades, and reject blocks that has unknown sudo inherents, or does not have expected sudo inherents.

Switching council

Each council switching operation will require the client to recalculate weights of all stored blocks, so it’s not a cheap operation. Client should also allow end user to select multiple councils to follow for separated block ranges.