InvalidBestNode error (#9364)
On Glamsterdam devnets we started seeing Lighthouse nodes unable to start with errors like:
> May 26 04:34:01.582 CRIT Failed to start beacon node reason: "Unable to load fork choice from disk: ForkChoiceError(ProtoArrayStringError(\"find_head failed: InvalidBestNode(InvalidBestNodeInfo { current_slot: Slot(23550), start_root: 0x2c70b1641c29ec46360c99f9a8512f077862cbbc603e16f4a423007d210b0c5f, justified_checkpoint: Checkpoint { epoch: Epoch(712), root: 0x2c70b1641c29ec46360c99f9a8512f077862cbbc603e16f4a423007d210b0c5f }, finalized_checkpoint: Checkpoint { epoch: Epoch(710), root: 0xede5e0b09b51bdb5445ade3398e685bd193b845e0b0ffb827f0c3fec8277ea51 }, head_root: 0x2c70b1641c29ec46360c99f9a8512f077862cbbc603e16f4a423007d210b0c5f, head_justified_checkpoint: Checkpoint { epoch: Epoch(710), root: 0xede5e0b09b51bdb5445ade3398e685bd193b845e0b0ffb827f0c3fec8277ea51 }, head_finalized_checkpoint: Checkpoint { epoch: Epoch(709), root: 0xbb243eff616ff362c52b83113e7c536d0a68cb9ca3d6a1cb1055e732219d9736 } })\"))"
This error was the result of an overly-strict sanity check, based on assumptions that are not true under extreme network conditions.
Completely remove the `InvalidBestNode` failure path: it is not compliant with the spec, and is actively harmful when triggered (it prevents Lighthouse from starting at all). The error was reachable in any situation where all leaf nodes of fork choice were ineligible to be the head. The payload invalidation tests show some examples of cases where this would happen, and the [newly-added regression test](9a5df1d982) shows a contrived case where it can happen on a Gloas network without _any_ slashings or invalid blocks. There are probably many more cases where it can happen.
We do not lose anything by removing it. The spec's implementation of `get_head` _always_ returns something (unless it crashes), and in these cases it is correct to return the starting node of the traversal: the justified checkpoint block. This is what we now do, and what the new test verifies.
I've also added some facilities to the harness for injecting attestations with fixed `payload_present` fields. @hopinheimer found himself needing something similar when messing with reorg tests, so I think these are probably useful. It might be possible to do without them by juggling the payload reveal timing in just the right way, but I think this approach is just way simpler.
Co-Authored-By: Michael Sproul <michael@sigmaprime.io>
Lighthouse: Ethereum consensus client
An open-source Ethereum consensus client, written in Rust and maintained by Sigma Prime.
Overview
Lighthouse is:
- Ready for use on Ethereum consensus mainnet.
- Fully open-source, licensed under Apache 2.0.
- Security-focused. Fuzzing techniques have been continuously applied and several external security reviews have been performed.
- Built in Rust, a modern language providing unique safety guarantees and excellent performance (comparable to C++).
- Funded by various organisations, including Sigma Prime, the Ethereum Foundation, Consensys, the Decentralization Foundation and private individuals.
- Actively involved in the specification and security analysis of the Ethereum proof-of-stake consensus specification.
Staking Deposit Contract
The Lighthouse team acknowledges
0x00000000219ab540356cBB839Cbe05303d7705Fa
as the canonical staking deposit contract address.
Documentation
The Lighthouse Book contains information for users and developers.
The Lighthouse team maintains a blog at https://blog.sigmaprime.io/tag/lighthouse which contains periodic progress updates, roadmap insights and interesting findings.
Branches
Lighthouse maintains two permanent branches:
stable: Always points to the latest stable release.- This is ideal for most users.
unstable: Used for development, contains the latest PRs.- Developers should base their PRs on this branch.
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Lighthouse welcomes contributors.
If you are looking to contribute, please head to the Contributing section of the Lighthouse book.
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The best place for discussion is the Lighthouse Discord server.
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Lighthouse is an open-source project and a public good. Funding public goods is hard and we're grateful for the donations we receive from the community via:
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- Ethereum address:
0x25c4a76E7d118705e7Ea2e9b7d8C59930d8aCD3b(donation.sigmaprime.eth).
