89 lines
3.0 KiB
Markdown
89 lines
3.0 KiB
Markdown
# Lighthouse Validator Client
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The Validator Client (VC) is a stand-alone binary which connects to a Beacon
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Node (BN) and fulfils the roles of a validator.
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## Roles
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The VC is responsible for the following tasks:
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- Requesting validator duties (a.k.a. shuffling) from the BN.
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- Prompting the BN to produce a new block, when a validators block production
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duties require.
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- Completing all the fields on a new block (e.g., RANDAO reveal, signature) and
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publishing the block to a BN.
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- Prompting the BN to produce a new shard attestation as per a validators
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duties.
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- Ensuring that no slashable messages are signed by a validator private key.
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- Keeping track of the system clock and how it relates to slots/epochs.
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The VC is capable of managing multiple validators in the same process tree.
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## Implementation
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_This section describes the present implementation of this VC binary._
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### Services
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Each validator is represented by two services, one which tracks the validator
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duties and another which performs block production duties.
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A separate thread is maintained for each service, for each validator. As such,
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a single validator utilises three (3) threads (one for the base VC and two for
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each service) and two validators utilise five (5) threads.
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#### `DutiesManagerService`
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Polls a BN and requests validator responsibilities, as well as a validator
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index. The outcome of a successful poll is a `EpochDuties` struct:
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```rust
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EpochDuties {
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validator_index: u64,
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block_production_slot: u64,
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}
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```
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This is stored in the `EpochDutiesMap`, a `HashMap` mapping `epoch ->
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EpochDuties`.
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#### `BlockProducerService`
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Polls the system clock and determines if a block needs to be produced. Reads
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from the `EpochDutiesMap` maintained by the `DutiesManagerService`.
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If block production is required, performs all the necessary duties to request,
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complete and return a block from the BN.
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### Configuration
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Validator configurations are stored in a separate data directory from the main Beacon Node
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binary. The validator data directory defaults to:
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`$HOME/.lighthouse-validator`, however an alternative can be specified on the command line
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with `--datadir`.
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The configuration directory structure looks like:
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```
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~/.lighthouse-validator
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├── 3cf4210d58ec
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│ └── private.key
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├── 9b5d8b5be4e7
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│ └── private.key
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└── cf6e07188f48
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└── private.key
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```
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Where the hex value of the directory is a portion of the validator public key.
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Validator keys must be generated using the separate `account_manager` binary, which will
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place the keys into this directory structure in a format compatible with the validator client.
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Be sure to check the readme for `account_manager`.
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The chain specification (slot length, BLS domain, etc.) defaults to foundation
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parameters, however is temporary and an upgrade will allow these parameters to be
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read from a file (or initialized on first-boot).
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## BN Communication
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The VC communicates with the BN via a gRPC/protobuf connection.
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