Dev Update Week 9 (robzajac)

Last week I continued development of the light client server endpoints in teku:

• Merged in PR for implementation of GetLightClientBootstrap
  • Made a few iterations on the feature after code review from the teku team
  • Tested and confirmed we receive the block header and sync committee associated with the block root given by the caller
  • Documented some followups to come out of this PR, like verifying the merkle proof implementation and an acceptance test against the endpoint /eth/v2/debug/beacon/states/{state_id}
• Implemented and opened a PR for the API stub and SSZ types of GetLightClientUpdatesByRange
  • PR adds the REST API endpoint and the backing SSZ types for LightClientUpdate
  • Identified that this endpoint has a custom encoding for the application/octet-stream response type. Clarified with the teku team how this can be implemented with the client's serialization library. Planning a followup PR to implement the custom encoding
• Organized the remaining project work in the teku tracking issue
  • The main work is in the implementation of GetLightClientUpdatesByRange, as the remaining endpoints can most likely reuse its business logic
  • Another significant piece will be implementing a LightClientUpdate cache storing historic light client data, since accessing several historic BeaconState would mean a major performance impact
  • Outside of the major components, there will be some minor UX/cleanup features, like adding a client flag for light client support and exposing the light client data via libp2p gossip (in addition to the REST API)

This week I would like to work on:

• Merging in the open PR for GetLightClientUpdatesByRange
• Adding an acceptance test for GetLightClientBootstrap, to verify whether this one is ready for the next teku release.
• Adding the --light-client-support-enabled flag. May be helpful before the first endpoint comes online, so that clients have the option of not serving the data (e.g. if hardware-constrained)
• (Time permitting) Beginning business logic of GetLightClientUpdatesByRange