## Issue Addressed
#3006
## Proposed Changes
This PR changes the default behaviour of lighthouse to ignore discovered IPs that are not globally routable. It adds a CLI flag, --enable-local-discovery to permit the non-global IPs in discovery.
NOTE: We should take care in merging this as I will break current set-ups that rely on local IP discovery. I made this the non-default behaviour because we dont really want to be wasting resources attempting to connect to non-routable addresses and we dont want to propagate these to others (on the chance we can connect to one of these local nodes), improving discoveries efficiency.
## Description
This PR adds a single, trivial commit (f5d2b27d78349d5a675a2615eba42cc9ae708094) atop #2986 to resolve a tests compile error. The original author (@ethDreamer) is AFK so I'm getting this one merged ☺️
Please see #2986 for more information about the other, significant changes in this PR.
Co-authored-by: Mark Mackey <mark@sigmaprime.io>
Co-authored-by: ethDreamer <37123614+ethDreamer@users.noreply.github.com>
## Proposed Changes
Lots of lint updates related to `flat_map`, `unwrap_or_else` and string patterns. I did a little more creative refactoring in the op pool, but otherwise followed Clippy's suggestions.
## Additional Info
We need this PR to unblock CI.
## Issue Addressed
I noticed in some logs some excess and unecessary discovery queries. What was happening was we were pruning our peers down to our outbound target and having some disconnect. When we are below this threshold we try to find more peers (even if we are at our peer limit). The request becomes futile because we have no more peer slots.
This PR corrects this issue and advances the pruning mechanism to favour subnet peers.
An overview the new logic added is:
- We prune peers down to a target outbound peer count which is higher than the minimum outbound peer count.
- We only search for more peers if there is room to do so, and we are below the minimum outbound peer count not the target. So this gives us some buffer for peers to disconnect. The buffer is currently 10%
The modified pruning logic is documented in the code but for reference it should do the following:
- Prune peers with bad scores first
- If we need to prune more peers, then prune peers that are subscribed to a long-lived subnet
- If we still need to prune peers, the prune peers that we have a higher density of on any given subnet which should drive for uniform peers across all subnets.
This will need a bit of testing as it modifies some significant peer management behaviours in lighthouse.
## Issue Addressed
Lighthouse gossiping late messages
## Proposed Changes
Point LH to our fork using tokio interval, which 1) works as expected 2) is more performant than the previous version that actually worked as expected
Upgrade libp2p
## Additional Info
https://github.com/libp2p/rust-libp2p/issues/2497
## Issue Addressed
NA
## Proposed Changes
Checks to see if attestations or sync messages are still valid before "accepting" them for propagation.
## Additional Info
NA
## Issue Addressed
NA
## Proposed Changes
Adds `STRICT_LATE_MESSAGE_PENALTIES: bool` which allows for toggling penalties for late sync/attn messages.
`STRICT_LATE_MESSAGE_PENALTIES` is set to `false`, since we're seeing a lot of late messages on the network which are causing peer drops. We can toggle the bool during testing to try and figure out what/who is the cause of these late messages.
In effect, this PR *relaxes* peer downscoring for late attns and sync committee messages.
## Additional Info
- ~~Blocked on #2974~~
## Issue Addressed
This PR fixes the unnecessary `WARN Single block lookup failed` messages described here:
https://github.com/sigp/lighthouse/pull/2866#issuecomment-1008442640
## Proposed Changes
Add a new cache to the `BeaconChain` that tracks the block roots of blocks from before finalization. These could be blocks from the canonical chain (which might need to be read from disk), or old pre-finalization blocks that have been forked out.
The cache also stores a set of block roots for in-progress single block lookups, which duplicates some of the information from sync's `single_block_lookups` hashmap:
a836e180f9/beacon_node/network/src/sync/manager.rs (L192-L196)
On a live node you can confirm that the cache is working by grepping logs for the message: `Rejected attestation to finalized block`.
Checking how to priorize the polling of the network I moved most of the service code to functions. This change I think it's worth on it's own for code quality since inside the `tokio::select` many tools don't work (cargo fmt, sometimes clippy, and sometimes even the compiler's errors get wack). This is functionally equivalent to the previous code, just better organized
## Proposed Changes
Initially the idea was to remove hashing of blocks in backfill sync. After considering it more, we conclude that we need to do it in both (forward and backfill) anyway. But since we forgot why we were doing it in the first place, this PR documents this logic.
Future us should find it useful
Co-authored-by: Divma <26765164+divagant-martian@users.noreply.github.com>
## Proposed Changes
Allocate less memory in sync by hashing the `SignedBeaconBlock`s in a batch directly, rather than going via SSZ bytes.
Credit to @paulhauner for finding this source of temporary allocations.
## Issue Addressed
- Resolves https://github.com/sigp/lighthouse/issues/2902
## Proposed Changes
As documented in https://github.com/sigp/lighthouse/issues/2902, there are some cases where we will score peers very harshly for sending attestations to an unknown head.
This PR removes the penalty when an attestation for an unknown head is received, queued for block look-up, then popped from the queue without the head block being known. This prevents peers from being penalized for an unknown block when that peer was never actually asked for the block.
Peer penalties should still be applied to the peers who *do* get the request for the block and fail to respond with a valid block. As such, peers who send us attestations to non-existent heads should eventually be booted.
## Additional Info
- [ ] Need to confirm that a timeout for a bbroot request will incur a penalty.
## Issue Addressed
NA
## Proposed Changes
We have observed occasions were under-resourced nodes will receive messages that were valid *at the time*, but later become invalidated due to long waits for a `BeaconProcessor` worker.
In this PR, we will check to see if the message was valid *at the time of receipt*. If it was initially valid but invalid now, we just ignore the message without penalizing the peer.
## Additional Info
NA
## Issue Addressed
NA
## Proposed Changes
I've observed some Prater nodes (and potentially some mainnet nodes) banning peers due to validator pubkey cache lock timeouts. For the `BeaconChainError`-type of errors, they're caused by internal faults and we can't necessarily tell if the peer is bad or not. I think this is causing us to ban peers unnecessarily when running on under-resourced machines.
## Additional Info
NA
## Issue Addressed
NA
## Proposed Changes
Introduces a cache to attestation to produce atop blocks which will become the head, but are not fully imported (e.g., not inserted into the database).
Whilst attesting to a block before it's imported is rather easy, if we're going to produce that attestation then we also need to be able to:
1. Verify that attestation.
1. Respond to RPC requests for the `beacon_block_root`.
Attestation verification (1) is *partially* covered. Since we prime the shuffling cache before we insert the block into the early attester cache, we should be fine for all typical use-cases. However, it is possible that the cache is washed out before we've managed to insert the state into the database and then attestation verification will fail with a "missing beacon state"-type error.
Providing the block via RPC (2) is also partially covered, since we'll check the database *and* the early attester cache when responding a blocks-by-root request. However, we'll still omit the block from blocks-by-range requests (until the block lands in the DB). I *think* this is fine, since there's no guarantee that we return all blocks for those responses.
Another important consideration is whether or not the *parent* of the early attester block is available in the databse. If it were not, we might fail to respond to blocks-by-root request that are iterating backwards to collect a chain of blocks. I argue that *we will always have the parent of the early attester block in the database.* This is because we are holding the fork-choice write-lock when inserting the block into the early attester cache and we do not drop that until the block is in the database.
## Issue Addressed
#2834
## Proposed Changes
Change log message severity from error to debug in attestation verification when attestation state is finalized.
## Issue Addressed
New rust lints
## Proposed Changes
- Boxing some enum variants
- removing some unused fields (is the validator lockfile unused? seemed so to me)
## Additional Info
- some error fields were marked as dead code but are logged out in areas
- left some dead fields in our ef test code because I assume they are useful for debugging?
Co-authored-by: realbigsean <seananderson33@gmail.com>
* update initializing from eth1 for merge genesis
* read execution payload header from file lcli
* add `create-payload-header` command to `lcli`
* fix base fee parsing
* Apply suggestions from code review
* default `execution_payload_header` bool to false when deserializing `meta.yml` in EF tests
Co-authored-by: Paul Hauner <paul@paulhauner.com>
* Add payload verification status to fork choice
* Pass payload verification status to import_block
* Add valid back-propagation
* Add head safety status latch to API
* Remove ExecutionLayerStatus
* Add execution info to client notifier
* Update notifier logs
* Change use of "hash" to refer to beacon block
* Shutdown on invalid finalized block
* Tidy, add comments
* Fix failing FC tests
* Allow blocks with unsafe head
* Fix forkchoiceUpdate call on startup
* Thread eth1_block_hash into interop genesis state
* Add merge-fork-epoch flag
* Build LH with minimal spec by default
* Add verbose logs to execution_layer
* Add --http-allow-sync-stalled flag
* Update lcli new-testnet to create genesis state
* Fix http test
* Fix compile errors in tests
Added Execution Payload from Rayonism Fork
Updated new Containers to match Merge Spec
Updated BeaconBlockBody for Merge Spec
Completed updating BeaconState and BeaconBlockBody
Modified ExecutionPayload<T> to use Transaction<T>
Mostly Finished Changes for beacon-chain.md
Added some things for fork-choice.md
Update to match new fork-choice.md/fork.md changes
ran cargo fmt
Added Missing Pieces in eth2_libp2p for Merge
fix ef test
Various Changes to Conform Closer to Merge Spec
## Issue Addressed
Closes#1996
## Proposed Changes
Run a second `Logger` via `sloggers` which logs to a file in the background with:
- separate `debug-level` for background and terminal logging
- the ability to limit log size
- rotation through a customizable number of log files
- an option to compress old log files (`.gz` format)
Add the following new CLI flags:
- `--logfile-debug-level`: The debug level of the log files
- `--logfile-max-size`: The maximum size of each log file
- `--logfile-max-number`: The number of old log files to store
- `--logfile-compress`: Whether to compress old log files
By default background logging uses the `debug` log level and saves logfiles to:
- Beacon Node: `$HOME/.lighthouse/$network/beacon/logs/beacon.log`
- Validator Client: `$HOME/.lighthouse/$network/validators/logs/validator.log`
Or, when using the `--datadir` flag:
`$datadir/beacon/logs/beacon.log` and `$datadir/validators/logs/validator.log`
Once rotated, old logs are stored like so: `beacon.log.1`, `beacon.log.2` etc.
> Note: `beacon.log.1` is always newer than `beacon.log.2`.
## Additional Info
Currently the default value of `--logfile-max-size` is 200 (MB) and `--logfile-max-number` is 5.
This means that the maximum storage space that the logs will take up by default is 1.2GB.
(200MB x 5 from old log files + <200MB the current logfile being written to)
Happy to adjust these default values to whatever people think is appropriate.
It's also worth noting that when logging to a file, we lose our custom `slog` formatting. This means the logfile logs look like this:
```
Oct 27 16:02:50.305 INFO Lighthouse started, version: Lighthouse/v2.0.1-8edd9d4+, module: lighthouse:413
Oct 27 16:02:50.305 INFO Configured for network, name: prater, module: lighthouse:414
```
We were batch removing chains when purging, and then updating the status of the collection for each of those. This makes the range status be out of sync with the real status. This represented no harm to the global sync status, but I've changed it to comply with a correct debug assertion that I got triggered while doing some testing.
Also added tests and improved code quality as per @paulhauner 's suggestions.
## Issue Addressed
Part of a bigger effort to make the network globals read only. This moves all writes to the `PeerDB` to the `eth2_libp2p` crate. Limiting writes to the peer manager is a slightly more complicated issue for a next PR, to keep things reviewable.
## Proposed Changes
- Make the peers field in the globals a private field.
- Allow mutable access to the peers field to `eth2_libp2p` for now.
- Add a new network message to update the sync state.
Co-authored-by: Age Manning <Age@AgeManning.com>
## Issue Addressed
Running a beacon node I triggered a sync debug panic. And so finally the time to create tests for sync arrived. Fortunately, te bug was not in the sync algorithm itself but a wrong assertion
## Proposed Changes
- Split Range's impl from the BeaconChain via a trait. This is needed for testing. The TestingRig/Harness is way bigger than needed and does not provide the modification functionalities that are needed to test sync. I find this simpler, tho some could disagree.
- Add a regression test for sync that fails before the changes.
- Fix the wrong assertion.
RPC Responses are for some reason not removing their timeout when they are completing.
As an example:
```
Nov 09 01:18:20.256 DEBG Received BlocksByRange Request step: 1, start_slot: 728465, count: 64, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:20.263 DEBG Received BlocksByRange Request step: 1, start_slot: 728593, count: 64, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:20.483 DEBG BlocksByRange Response sent returned: 63, requested: 64, current_slot: 2466389, start_slot: 728465, msg: Failed to return all requested blocks, peer: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:20.500 DEBG BlocksByRange Response sent returned: 64, requested: 64, current_slot: 2466389, start_slot: 728593, peer: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:21.068 DEBG Received BlocksByRange Request step: 1, start_slot: 728529, count: 64, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:21.272 DEBG BlocksByRange Response sent returned: 63, requested: 64, current_slot: 2466389, start_slot: 728529, msg: Failed to return all requested blocks, peer: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:23.434 DEBG Received BlocksByRange Request step: 1, start_slot: 728657, count: 64, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:23.665 DEBG BlocksByRange Response sent returned: 64, requested: 64, current_slot: 2466390, start_slot: 728657, peer: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:25.851 DEBG Received BlocksByRange Request step: 1, start_slot: 728337, count: 64, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:25.851 DEBG Received BlocksByRange Request step: 1, start_slot: 728401, count: 64, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:26.094 DEBG BlocksByRange Response sent returned: 62, requested: 64, current_slot: 2466390, start_slot: 728401, msg: Failed to return all requested blocks, peer: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:26.100 DEBG BlocksByRange Response sent returned: 63, requested: 64, current_slot: 2466390, start_slot: 728337, msg: Failed to return all requested blocks, peer: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw
Nov 09 01:18:31.070 DEBG RPC Error direction: Incoming, score: 0, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw, client: Prysm: version: a80b1c252a9b4773493b41999769bf3134ac373f, os_version: unknown, err: Stream Timeout, protocol: beacon_blocks_by_range, service: libp2p
Nov 09 01:18:31.070 WARN Timed out to a peer's request. Likely insufficient resources, reduce peer count, service: libp2p
Nov 09 01:18:31.085 DEBG RPC Error direction: Incoming, score: 0, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw, client: Prysm: version: a80b1c252a9b4773493b41999769bf3134ac373f, os_version: unknown, err: Stream Timeout, protocol: beacon_blocks_by_range, service: libp2p
Nov 09 01:18:31.085 WARN Timed out to a peer's request. Likely insufficient resources, reduce peer count, service: libp2p
Nov 09 01:18:31.459 DEBG RPC Error direction: Incoming, score: 0, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw, client: Prysm: version: a80b1c252a9b4773493b41999769bf3134ac373f, os_version: unknown, err: Stream Timeout, protocol: beacon_blocks_by_range, service: libp2p
Nov 09 01:18:31.459 WARN Timed out to a peer's request. Likely insufficient resources, reduce peer count, service: libp2p
Nov 09 01:18:34.129 DEBG RPC Error direction: Incoming, score: 0, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw, client: Prysm: version: a80b1c252a9b4773493b41999769bf3134ac373f, os_version: unknown, err: Stream Timeout, protocol: beacon_blocks_by_range, service: libp2p
Nov 09 01:18:34.130 WARN Timed out to a peer's request. Likely insufficient resources, reduce peer count, service: libp2p
Nov 09 01:18:35.686 DEBG Peer Manager disconnecting peer reason: Too many peers, peer_id: 16Uiu2HAmEmBURejquBUMgKAqxViNoPnSptTWLA2CfgSPnnKENBNw, service: libp2p
```
This PR is to investigate and correct the issue.
~~My current thoughts are that for some reason we are not closing the streams correctly, or fast enough, or the executor is not registering the closes and waking up.~~ - Pretty sure this is not the case, see message below for a more accurate reason.
~~I've currently added a timeout to stream closures in an attempt to force streams to close and the future to always complete.~~ I removed this
## Issue Addressed
The computation of metrics in the network service can be expensive. This disables the computation unless the cli flag `metrics` is set.
## Additional Info
Metrics in other parts of the network are still updated, since most are simple metrics and checking if metrics are enabled each time each metric is updated doesn't seem like a gain.
## Issue Addressed
Getting too many peers kicked due to slightly late sync committee messages as tested on.. under-performant hardware.
## Proposed Changes
Only penalize if the message is more than one slot late. Still ignore the message-
Co-authored-by: Divma <26765164+divagant-martian@users.noreply.github.com>
## Issue Addressed
The [p2p-interface section of the `altair` spec](https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/p2p-interface.md#transitioning-the-gossip) says you should subscribe to the topics for a fork "In advance of the fork" and unsubscribe from old topics `2 Epochs` after the new fork is activated. We've chosen to subscribe to new fork topics `2 slots` before the fork is initiated.
This function is supposed to return the required fork digests at any given time but as it was currently written, it doesn't return the fork digest for a previous fork if you've switched to the current fork less than 2 epoch's ago. Also this function required modification for every new fork we add.
## Proposed Changes
Make this function fork-agnostic and correctly handle the previous fork topic digests when you've only just switched to the new fork.
## Issue Addressed
Resolves#2611
## Proposed Changes
Adds a duplicate block root cache to the `BeaconProcessor`. Adds the block root to the cache before calling `process_gossip_block` and `process_rpc_block`. Since `process_rpc_block` is called only for single block lookups, we don't have to worry about batched block imports.
The block is imported from the source(gossip/rpc) that arrives first. The block that arrives second is not imported to avoid the db access issue.
There are 2 cases:
1. Block that arrives second is from rpc: In this case, we return an optimistic `BlockError::BlockIsAlreadyKnown` to sync.
2. Block that arrives second is from gossip: In this case, we only do gossip verification and forwarding but don't import the block into the the beacon chain.
## Additional info
Splits up `process_gossip_block` function to `process_gossip_unverified_block` and `process_gossip_verified_block`.
## Issue Addressed
In the backfill sync the state was maintained twice, once locally and also in the globals. This makes it so that it's maintained only once.
The only behavioral change is that when backfill sync in paused, the global backfill state is updated. I asked @AgeManning about this and he deemed it a bug, so this solves it.
## Description
The `eth2_libp2p` crate was originally named and designed to incorporate a simple libp2p integration into lighthouse. Since its origins the crates purpose has expanded dramatically. It now houses a lot more sophistication that is specific to lighthouse and no longer just a libp2p integration.
As of this writing it currently houses the following high-level lighthouse-specific logic:
- Lighthouse's implementation of the eth2 RPC protocol and specific encodings/decodings
- Integration and handling of ENRs with respect to libp2p and eth2
- Lighthouse's discovery logic, its integration with discv5 and logic about searching and handling peers.
- Lighthouse's peer manager - This is a large module handling various aspects of Lighthouse's network, such as peer scoring, handling pings and metadata, connection maintenance and recording, etc.
- Lighthouse's peer database - This is a collection of information stored for each individual peer which is specific to lighthouse. We store connection state, sync state, last seen ips and scores etc. The data stored for each peer is designed for various elements of the lighthouse code base such as syncing and the http api.
- Gossipsub scoring - This stores a collection of gossipsub 1.1 scoring mechanisms that are continuously analyssed and updated based on the ethereum 2 networks and how Lighthouse performs on these networks.
- Lighthouse specific types for managing gossipsub topics, sync status and ENR fields
- Lighthouse's network HTTP API metrics - A collection of metrics for lighthouse network monitoring
- Lighthouse's custom configuration of all networking protocols, RPC, gossipsub, discovery, identify and libp2p.
Therefore it makes sense to rename the crate to be more akin to its current purposes, simply that it manages the majority of Lighthouse's network stack. This PR renames this crate to `lighthouse_network`
Co-authored-by: Paul Hauner <paul@paulhauner.com>
## Issue Addressed
NA
## Proposed Changes
This PR is near-identical to https://github.com/sigp/lighthouse/pull/2652, however it is to be merged into `unstable` instead of `merge-f2f`. Please see that PR for reasoning.
I'm making this duplicate PR to merge to `unstable` in an effort to shrink the diff between `unstable` and `merge-f2f` by doing smaller, lead-up PRs.
## Additional Info
NA
## Proposed Changes
This is a refactor of the PeerDB and PeerManager. A number of bugs have been surfacing around the connection state of peers and their interaction with the score state.
This refactor tightens the mutability properties of peers such that only specific modules are able to modify the state of peer information preventing inadvertant state changes that can lead to our local peer manager db being out of sync with libp2p.
Further, the logic around connection and scoring was quite convoluted and the distinction between the PeerManager and Peerdb was not well defined. Although these issues are not fully resolved, this PR is step to cleaning up this logic. The peerdb solely manages most mutability operations of peers leaving high-order logic to the peer manager.
A single `update_connection_state()` function has been added to the peer-db making it solely responsible for modifying the peer's connection state. The way the peer's scores can be modified have been reduced to three simple functions (`update_scores()`, `update_gossipsub_scores()` and `report_peer()`). This prevents any add-hoc modifications of scores and only natural processes of score modification is allowed which simplifies the reasoning of score and state changes.
## Issue Addressed
N/A
## Proposed Changes
When peers switching to a disconnecting state, decrement the disconnected peers counter. This also downgrades some crit logs to errors.
I've also added a re-sync point when peers get unbanned the disconnected peer count will match back to the number of disconnected peers if it has gone out of sync previously.
## Issue Addressed
Closes#2528
## Proposed Changes
- Add `BlockTimesCache` to provide block timing information to `BeaconChain`. This allows additional metrics to be calculated for blocks that are set as head too late.
- Thread the `seen_timestamp` of blocks received from RPC responses (except blocks from syncing) through to the sync manager, similar to what is done for blocks from gossip.
## Additional Info
This provides the following additional metrics:
- `BEACON_BLOCK_OBSERVED_SLOT_START_DELAY_TIME`
- The delay between the start of the slot and when the block was first observed.
- `BEACON_BLOCK_IMPORTED_OBSERVED_DELAY_TIME`
- The delay between when the block was first observed and when the block was imported.
- `BEACON_BLOCK_HEAD_IMPORTED_DELAY_TIME`
- The delay between when the block was imported and when the block was set as head.
The metric `BEACON_BLOCK_IMPORTED_SLOT_START_DELAY_TIME` was removed.
A log is produced when a block is set as head too late, e.g.:
```
Aug 27 03:46:39.006 DEBG Delayed head block set_as_head_delay: Some(21.731066ms), imported_delay: Some(119.929934ms), observed_delay: Some(3.864596988s), block_delay: 4.006257988s, slot: 1931331, proposer_index: 24294, block_root: 0x937602c89d3143afa89088a44bdf4b4d0d760dad082abacb229495c048648a9e, service: beacon
```
## Issue Addressed
NA
## Proposed Changes
Implements the "union" type from the SSZ spec for `ssz`, `ssz_derive`, `tree_hash` and `tree_hash_derive` so it may be derived for `enums`:
https://github.com/ethereum/consensus-specs/blob/v1.1.0-beta.3/ssz/simple-serialize.md#union
The union type is required for the merge, since the `Transaction` type is defined as a single-variant union `Union[OpaqueTransaction]`.
### Crate Updates
This PR will (hopefully) cause CI to publish new versions for the following crates:
- `eth2_ssz_derive`: `0.2.1` -> `0.3.0`
- `eth2_ssz`: `0.3.0` -> `0.4.0`
- `eth2_ssz_types`: `0.2.0` -> `0.2.1`
- `tree_hash`: `0.3.0` -> `0.4.0`
- `tree_hash_derive`: `0.3.0` -> `0.4.0`
These these crates depend on each other, I've had to add a workspace-level `[patch]` for these crates. A follow-up PR will need to remove this patch, ones the new versions are published.
### Union Behaviors
We already had SSZ `Encode` and `TreeHash` derive for enums, however it just did a "transparent" pass-through of the inner value. Since the "union" decoding from the spec is in conflict with the transparent method, I've required that all `enum` have exactly one of the following enum-level attributes:
#### SSZ
- `#[ssz(enum_behaviour = "union")]`
- matches the spec used for the merge
- `#[ssz(enum_behaviour = "transparent")]`
- maintains existing functionality
- not supported for `Decode` (never was)
#### TreeHash
- `#[tree_hash(enum_behaviour = "union")]`
- matches the spec used for the merge
- `#[tree_hash(enum_behaviour = "transparent")]`
- maintains existing functionality
This means that we can maintain the existing transparent behaviour, but all existing users will get a compile-time error until they explicitly opt-in to being transparent.
### Legacy Option Encoding
Before this PR, we already had a union-esque encoding for `Option<T>`. However, this was with the *old* SSZ spec where the union selector was 4 bytes. During merge specification, the spec was changed to use 1 byte for the selector.
Whilst the 4-byte `Option` encoding was never used in the spec, we used it in our database. Writing a migrate script for all occurrences of `Option` in the database would be painful, especially since it's used in the `CommitteeCache`. To avoid the migrate script, I added a serde-esque `#[ssz(with = "module")]` field-level attribute to `ssz_derive` so that we can opt into the 4-byte encoding on a field-by-field basis.
The `ssz::legacy::four_byte_impl!` macro allows a one-liner to define the module required for the `#[ssz(with = "module")]` for some `Option<T> where T: Encode + Decode`.
Notably, **I have removed `Encode` and `Decode` impls for `Option`**. I've done this to force a break on downstream users. Like I mentioned, `Option` isn't used in the spec so I don't think it'll be *that* annoying. I think it's nicer than quietly having two different union implementations or quietly breaking the existing `Option` impl.
### Crate Publish Ordering
I've modified the order in which CI publishes crates to ensure that we don't publish a crate without ensuring we already published a crate that it depends upon.
## TODO
- [ ] Queue a follow-up `[patch]`-removing PR.
