Tracking issue for Polkadot Bulletin Chain <> Polkadot Bridge Hub bridge

[svyatonik]

All development should happen in master and then backported to the polkadot-v.1.0.0-audited branch (and polkadot-staging eventually).

Tasks that would allow us to test it locally:

• add Bulletin Chain primitives (Add polkadot bulletin chain primitives #2542);
• add required pallets to Polkadot Bridge Hub (on top of [asset-hubs/bridge-hubs] Bridging Polkadot Asset Hub <-> Kusama Asset Hub to enable asset transfer of KSMs/DOTs polkadot-sdk#1352) (https://github.com/paritytech/polkadot-sdk/tree/sv-bulletin-chain-bridge):
  • make sure that we only register transaction fee refunds and are not paying any rewards to relayers;
• add required pallets to Bulletin Chain (https://github.com/svyatonik/polkadot-bulletin-chain/tree/add-bridge-pallets):
  • add XCM support to Bulletin Chain (hopefully someone from XCM team could help with that);
  • decide whether we want to use utility pallet there;
  • make sure that we only accept bridge transactions from whitelisted relayers;
  • do not register any rewards at Bulletin Chain, because tokens have no economic value there;
• add bridge support to substrate-relay;
• prepare something similar to Branislav setup (zombienet + binaries + document) to launch Polkadot + Polkadot Bridge Hub + Bulletin Chain (and another system parachain later) locally.
• send some test message directly from Polkadot BH to Bulletin Chain (unless other Polkadot parachain is ready).

Follow up tasks: make actual PRs to Polkadot.BH once it is deployed.

A list of live unresolved problems:

• we need to know real dispatch weight of the message. Bulletin chain uses immediate dispatch, so we need to decode the message (and calls) and use XCM weigher for estimating dispatch weight for message delivery transaction (Add bridge dispatcher and exporter zdave-parity/polkadot-bulletin-chain#33).
• rename Kawabunga to People Chain (see Rococo & Westend People Chain polkadot-sdk#2281)
• add Rococo Bridge Hub <> Rococo Bulletin bridge (Rococo Bulletin chain will be deployed and will be 1:1 copy of Polkadot Bulletin)

[svyatonik]

Rococo <> RococoBulletin bridge may be tested locally (until centralized deployment) with:

• https://github.com/paritytech/polkadot-sdk/tree/sv-rococo-bulletin-bridge
• Added Rococo BH <> Rococo Bulletin bridge #2724
• https://github.com/svyatonik/polkadot-bulletin-chain/tree/add-bridge-pallets

Instructions: https://github.com/paritytech/polkadot-sdk/blob/sv-rococo-bulletin-bridge/cumulus/parachains/runtimes/bridge-hubs/README-bulletin.md

[bkontur]

hint for me: just search TODOs for https://github.com/paritytech/parity-bridges-common/issues/2547 in the code