Standard gas limit api (#3450)

## Issue Addressed

Resolves https://github.com/sigp/lighthouse/issues/3403

## Proposed Changes

Implements https://ethereum.github.io/keymanager-APIs/#/Gas%20Limit

## Additional Info

N/A

Co-authored-by: realbigsean <sean@sigmaprime.io>

validator_client/src/http_api/mod.rs

@@ -12,7 +12,7 @@ use account_utils::{
 pub use api_secret::ApiSecret;
 use create_validator::{create_validators_mnemonic, create_validators_web3signer};
 use eth2::lighthouse_vc::{
-    std_types::{AuthResponse, GetFeeRecipientResponse},
+    std_types::{AuthResponse, GetFeeRecipientResponse, GetGasLimitResponse},
     types::{self as api_types, GenericResponse, PublicKey, PublicKeyBytes},
 };
 use lighthouse_version::version_with_platform;
@@ -626,8 +626,8 @@ pub fn serve<T: 'static + SlotClock + Clone, E: EthSpec>(
     let post_fee_recipient = eth_v1
         .and(warp::path("validator"))
         .and(warp::path::param::<PublicKey>())
-        .and(warp::body::json())
         .and(warp::path("feerecipient"))
+        .and(warp::body::json())
         .and(warp::path::end())
         .and(validator_store_filter.clone())
         .and(signer.clone())
@@ -700,6 +700,115 @@ pub fn serve<T: 'static + SlotClock + Clone, E: EthSpec>(
         )
         .map(|reply| warp::reply::with_status(reply, warp::http::StatusCode::NO_CONTENT));
 
+    // GET /eth/v1/validator/{pubkey}/gas_limit
+    let get_gas_limit = eth_v1
+        .and(warp::path("validator"))
+        .and(warp::path::param::<PublicKey>())
+        .and(warp::path("gas_limit"))
+        .and(warp::path::end())
+        .and(validator_store_filter.clone())
+        .and(signer.clone())
+        .and_then(
+            |validator_pubkey: PublicKey, validator_store: Arc<ValidatorStore<T, E>>, signer| {
+                blocking_signed_json_task(signer, move || {
+                    if validator_store
+                        .initialized_validators()
+                        .read()
+                        .is_enabled(&validator_pubkey)
+                        .is_none()
+                    {
+                        return Err(warp_utils::reject::custom_not_found(format!(
+                            "no validator found with pubkey {:?}",
+                            validator_pubkey
+                        )));
+                    }
+                    Ok(GenericResponse::from(GetGasLimitResponse {
+                        pubkey: PublicKeyBytes::from(validator_pubkey.clone()),
+                        gas_limit: validator_store
+                            .get_gas_limit(&PublicKeyBytes::from(&validator_pubkey)),
+                    }))
+                })
+            },
+        );
+
+    // POST /eth/v1/validator/{pubkey}/gas_limit
+    let post_gas_limit = eth_v1
+        .and(warp::path("validator"))
+        .and(warp::path::param::<PublicKey>())
+        .and(warp::path("gas_limit"))
+        .and(warp::body::json())
+        .and(warp::path::end())
+        .and(validator_store_filter.clone())
+        .and(signer.clone())
+        .and_then(
+            |validator_pubkey: PublicKey,
+             request: api_types::UpdateGasLimitRequest,
+             validator_store: Arc<ValidatorStore<T, E>>,
+             signer| {
+                blocking_signed_json_task(signer, move || {
+                    if validator_store
+                        .initialized_validators()
+                        .read()
+                        .is_enabled(&validator_pubkey)
+                        .is_none()
+                    {
+                        return Err(warp_utils::reject::custom_not_found(format!(
+                            "no validator found with pubkey {:?}",
+                            validator_pubkey
+                        )));
+                    }
+                    validator_store
+                        .initialized_validators()
+                        .write()
+                        .set_validator_gas_limit(&validator_pubkey, request.gas_limit)
+                        .map_err(|e| {
+                            warp_utils::reject::custom_server_error(format!(
+                                "Error persisting gas limit: {:?}",
+                                e
+                            ))
+                        })
+                })
+            },
+        )
+        .map(|reply| warp::reply::with_status(reply, warp::http::StatusCode::ACCEPTED));
+
+    // DELETE /eth/v1/validator/{pubkey}/gas_limit
+    let delete_gas_limit = eth_v1
+        .and(warp::path("validator"))
+        .and(warp::path::param::<PublicKey>())
+        .and(warp::path("gas_limit"))
+        .and(warp::path::end())
+        .and(validator_store_filter.clone())
+        .and(signer.clone())
+        .and_then(
+            |validator_pubkey: PublicKey, validator_store: Arc<ValidatorStore<T, E>>, signer| {
+                blocking_signed_json_task(signer, move || {
+                    if validator_store
+                        .initialized_validators()
+                        .read()
+                        .is_enabled(&validator_pubkey)
+                        .is_none()
+                    {
+                        return Err(warp_utils::reject::custom_not_found(format!(
+                            "no validator found with pubkey {:?}",
+                            validator_pubkey
+                        )));
+                    }
+                    validator_store
+                        .initialized_validators()
+                        .write()
+                        .delete_validator_gas_limit(&validator_pubkey)
+                        .map_err(|e| {
+                            warp_utils::reject::custom_server_error(format!(
+                                "Error persisting gas limit removal: {:?}",
+                                e
+                            ))
+                        })
+                })
+            },
+        )
+        .map(|reply| warp::reply::with_status(reply, warp::http::StatusCode::NO_CONTENT));
+
     // GET /eth/v1/keystores
     let get_std_keystores = std_keystores
         .and(signer.clone())
@@ -786,6 +895,7 @@ pub fn serve<T: 'static + SlotClock + Clone, E: EthSpec>(
                         .or(get_lighthouse_validators)
                         .or(get_lighthouse_validators_pubkey)
                         .or(get_fee_recipient)
+                        .or(get_gas_limit)
                         .or(get_std_keystores)
                         .or(get_std_remotekeys),
                 )
@@ -795,12 +905,14 @@ pub fn serve<T: 'static + SlotClock + Clone, E: EthSpec>(
                         .or(post_validators_mnemonic)
                         .or(post_validators_web3signer)
                         .or(post_fee_recipient)
+                        .or(post_gas_limit)
                         .or(post_std_keystores)
                         .or(post_std_remotekeys),
                 ))
                 .or(warp::patch().and(patch_validators))
                 .or(warp::delete().and(
                     delete_fee_recipient
+                        .or(delete_gas_limit)
                         .or(delete_std_keystores)
                         .or(delete_std_remotekeys),
                 )),