How to add validators and bootnodes in PoA, when sudo isn't there?

Question

I'd like to make sure that after sudo access is gone forever, there still remains the following functionality in our PoA blockchain:

1. new aura and grandpa validators can join.
2. new bootnodes can appear.

I guess, to implement such functionality, we don't need PoW or PoS, and all can be done with PoA combined with some kind of democratic voting among existing participants.

I'm willing to give an opportunity to anyone to become a validator and/or create a bootnode with my zero involvement, so that existing validators by themselves could accept newcomers willing to join.

So the question is: what pallets should I add to the blockchain, how am I supposed to change runtime or node to add such functionality?

The Private Network tutorial provide the answers only if I fully own the network, which I would like to avoid.

Answer 1

The bootnodes are configured in the chain spec. When you launch additional nodes, you can add bootnodes for that node.

Have you taken a look at the node-authorization pallet? It has a concept of normal nodes, well-known nodes, and sub-nodes which could fit your use-case.

If you haven't already take a look at the permissioned network tutorial:

• https://docs.substrate.io/tutorials/v3/permissioned-network/

In your use-case, you could set it up so that anyone can claim a peerId and hence a node.

You can add additional well-known nodes via an extrinsic which can come from sudo or governance.

If you want to integrate governance into your chain, I would start by looking into pallet_collective and pallet_democracy.

For example, you can see the governance pallets Kusama is using here:

• https://github.com/paritytech/polkadot/blob/master/runtime/kusama/src/lib.rs#L1391

... in your case you would not need PhragmenElection pallet.

Answer 2

For your scenario you might find useful the following pallets:

• Validator-manager This one is used in Rococo network (PoA).
• Substrate-validator-set Which can be used for add/remove validators in PoA networks.