Changes for Capella and EIP-4844

[metachris]

Capella and EIP-4844 will require changes to mev-boost, builder-specs, relay and builders.

• Both introduce new fields to BeaconBlockBody, ExecutionPayload and ExecutionPayloadHeader: eip4844 / capella
• This will break previous SSZ encoding/decoding (and strict JSON too), and needs a mev-boost update alongside EL+CL updates.
• MEV-Boost will need to know about multiple container versions and handle the forks correctly

Changes needed

Capella

• update types in mev-boost to know about both bellatrix and capella containers
• on getPayload, mev-boost detects whether payload is Capella or Bellatrix format and handles it correctly

EIP-4844

• changes TBD
• "For the relayer side, there's more work, they probably want to verify blobs, the commitments, and the version hashes are valid. Those will be coming from the builders" (@terencechain)

[metachris]

Related effort - using types from Attestant to reduce maintenance overhead:

• Proposal: replace types from go-boost-utils with types from Attestant #404
• Replace go-boost-utils types with Attestant types #411

[metachris]

Capella

Notes

• enables withdrawals
• https://github.com/ethereum/consensus-specs/tree/dev/specs/capella
• https://github.com/ethereum/consensus-specs/blob/dev/specs/capella/beacon-chain.md

Payload changes

• https://github.com/ethereum/consensus-specs/blob/dev/specs/capella/beacon-chain.md#extended-containers

Container	Change
ExecutionPayload	new field: withdrawals: List[Withdrawal, MAX_WITHDRAWALS_PER_PAYLOAD] # [New in Capella]
ExecutionPayloadHeader	new field: withdrawals_root: Root # [New in Capella]
BeaconBlockBody	new field: bls_to_execution_changes: List[SignedBLSToExecutionChange, MAX_BLS_TO_EXECUTION_CHANGES] # [New in Capella]
SignedBLSToExecutionChange	(new container)
BLSToExecutionChange	(new container)
Withdrawal	(new container)

[jimmygchen]

Hi @metachris
@0xGabi and I have started working on the builder spec changes for EIP-4844, will link the PR here we've pushed the changes!

I have created a PR on Beacon API updates which contains some types required for builder spec: ethereum/beacon-APIs#271

[jimmygchen]

We've created a draft PR on builder spec here here: ethereum/builder-specs#58

[metachris]

Closed in favor of #451