Builder Specs v0.2.0 (#3134)

## Issue Addressed

https://github.com/sigp/lighthouse/issues/3091

Extends https://github.com/sigp/lighthouse/pull/3062, adding pre-bellatrix block support on blinded endpoints and allowing the normal proposal flow (local payload construction) on blinded endpoints. This resulted in better fallback logic because the VC will not have to switch endpoints on failure in the BN <> Builder API, the BN can just fallback immediately and without repeating block processing that it shouldn't need to. We can also keep VC fallback from the VC<>BN API's blinded endpoint to full endpoint.

## Proposed Changes

- Pre-bellatrix blocks on blinded endpoints
- Add a new `PayloadCache` to the execution layer
- Better fallback-from-builder logic

## Todos

- [x] Remove VC transition logic
- [x] Add logic to only enable builder flow after Merge transition finalization
- [x] Tests
- [x] Fix metrics
- [x] Rustdocs


Co-authored-by: Mac L <mjladson@pm.me>
Co-authored-by: realbigsean <sean@sigmaprime.io>

common/eth2/src/lib.rs

@@ -1280,7 +1280,7 @@ impl BeaconNodeHttpClient {
         .await
     }
 
-    /// `GET v2/validator/blocks/{slot}`
+    /// `GET v1/validator/blinded_blocks/{slot}`
     pub async fn get_validator_blinded_blocks_with_verify_randao<
         T: EthSpec,
         Payload: ExecPayload<T>,
@@ -1291,7 +1291,7 @@ impl BeaconNodeHttpClient {
         graffiti: Option<&Graffiti>,
         verify_randao: Option<bool>,
     ) -> Result<ForkVersionedResponse<BeaconBlock<T, Payload>>, Error> {
-        let mut path = self.eth_path(V2)?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?

common/eth2/src/lighthouse_vc/http_client.rs

@@ -462,7 +462,9 @@ impl ValidatorClientHttpClient {
     pub async fn patch_lighthouse_validators(
         &self,
         voting_pubkey: &PublicKeyBytes,
-        enabled: bool,
+        enabled: Option<bool>,
+        gas_limit: Option<u64>,
+        builder_proposals: Option<bool>,
     ) -> Result<(), Error> {
         let mut path = self.server.full.clone();
 
@@ -472,7 +474,15 @@ impl ValidatorClientHttpClient {
             .push("validators")
             .push(&voting_pubkey.to_string());
 
-        self.patch(path, &ValidatorPatchRequest { enabled }).await
+        self.patch(
+            path,
+            &ValidatorPatchRequest {
+                enabled,
+                gas_limit,
+                builder_proposals,
+            },
+        )
+        .await
     }
 
     fn make_keystores_url(&self) -> Result<Url, Error> {

common/eth2/src/lighthouse_vc/types.rs

@@ -26,6 +26,12 @@ pub struct ValidatorRequest {
     #[serde(default)]
     #[serde(skip_serializing_if = "Option::is_none")]
     pub suggested_fee_recipient: Option<Address>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub gas_limit: Option<u64>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub builder_proposals: Option<bool>,
     #[serde(with = "eth2_serde_utils::quoted_u64")]
     pub deposit_gwei: u64,
 }
@@ -49,6 +55,12 @@ pub struct CreatedValidator {
     #[serde(default)]
     #[serde(skip_serializing_if = "Option::is_none")]
     pub suggested_fee_recipient: Option<Address>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub gas_limit: Option<u64>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub builder_proposals: Option<bool>,
     pub eth1_deposit_tx_data: String,
     #[serde(with = "eth2_serde_utils::quoted_u64")]
     pub deposit_gwei: u64,
@@ -62,7 +74,15 @@ pub struct PostValidatorsResponseData {
 
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct ValidatorPatchRequest {
-    pub enabled: bool,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub enabled: Option<bool>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub gas_limit: Option<u64>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub builder_proposals: Option<bool>,
 }
 
 #[derive(Clone, PartialEq, Serialize, Deserialize)]
@@ -70,8 +90,18 @@ pub struct KeystoreValidatorsPostRequest {
     pub password: ZeroizeString,
     pub enable: bool,
     pub keystore: Keystore,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub graffiti: Option<GraffitiString>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub suggested_fee_recipient: Option<Address>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub gas_limit: Option<u64>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub builder_proposals: Option<bool>,
 }
 
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
@@ -84,6 +114,12 @@ pub struct Web3SignerValidatorRequest {
     #[serde(default)]
     #[serde(skip_serializing_if = "Option::is_none")]
     pub suggested_fee_recipient: Option<Address>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub gas_limit: Option<u64>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub builder_proposals: Option<bool>,
     pub voting_public_key: PublicKey,
     pub url: String,
     #[serde(default)]