Require properly configured Engine API connection after the merge

beacon_chain/conf.nim

@@ -172,6 +172,11 @@ type
       desc: "Force the use of polling when determining the head block of Eth1"
       name: "web3-force-polling" .}: bool
 
+    requireEngineAPI* {.
+      defaultValue: true
+      desc: "Require Nimbus to be configured with an Engine API end-point after the Bellatrix fork epoch"
+      name: "require-engine-api-in-bellatrix" .}: bool
+
     nonInteractive* {.
       desc: "Do not display interative prompts. Quit on missing configuration"
       name: "non-interactive" .}: bool

beacon_chain/eth1/eth1_monitor.nim

@@ -141,6 +141,8 @@ type
     stopFut: Future[void]
     getBeaconTime: GetBeaconTimeFn
 
+    requireEngineAPI: bool
+
     when hasGenesisDetection:
       genesisValidators: seq[ImmutableValidatorData]
       genesisValidatorKeyToIndex: Table[ValidatorPubKey, ValidatorIndex]
@@ -548,53 +550,67 @@ proc forkchoiceUpdated*(p: Eth1Monitor,
 # TODO can't be defined within exchangeTransitionConfiguration
 proc `==`(x, y: Quantity): bool {.borrow, noSideEffect.}
 
-proc exchangeTransitionConfiguration*(p: Eth1Monitor): Future[void] {.async.} =
+type
+  EtcStatus {.pure.} = enum
+    exchangeError
+    mismatch
+    localConfigurationUpdated
+    match
+
+proc exchangeTransitionConfiguration*(p: Eth1Monitor): Future[EtcStatus] {.async.} =
   # Eth1 monitor can recycle connections without (external) warning; at least,
   # don't crash.
   if p.isNil:
     debug "exchangeTransitionConfiguration: nil Eth1Monitor"
 
   if p.isNil or p.dataProvider.isNil:
-    return
+    return EtcStatus.exchangeError
 
-  let ccTransitionConfiguration = TransitionConfigurationV1(
+  let consensusCfg = TransitionConfigurationV1(
     terminalTotalDifficulty: p.depositsChain.cfg.TERMINAL_TOTAL_DIFFICULTY,
     terminalBlockHash:
       if p.terminalBlockHash.isSome:
         p.terminalBlockHash.get
       else:
-        # https://github.com/nim-lang/Nim/issues/19802
-        (static(default(BlockHash))),
+        (static default BlockHash),
     terminalBlockNumber:
       if p.terminalBlockNumber.isSome:
         p.terminalBlockNumber.get
       else:
-        # https://github.com/nim-lang/Nim/issues/19802
-        (static(default(Quantity))))
-  let ecTransitionConfiguration =
+        (static default Quantity))
+  let executionCfg =
     try:
       awaitWithRetries(
         p.dataProvider.web3.provider.engine_exchangeTransitionConfigurationV1(
-          ccTransitionConfiguration),
+          consensusCfg),
         timeout = 1.seconds)
     except CatchableError as err:
-      debug "Failed to exchange transition configuration", err = err.msg
-      return
-
-  if ccTransitionConfiguration != ecTransitionConfiguration:
-    warn "exchangeTransitionConfiguration: Configuration mismatch detected",
-      consensusTerminalTotalDifficulty =
-        $ccTransitionConfiguration.terminalTotalDifficulty,
-      consensusTerminalBlockHash =
-        ccTransitionConfiguration.terminalBlockHash,
-      consensusTerminalBlockNumber =
-        ccTransitionConfiguration.terminalBlockNumber.uint64,
-      executionTerminalTotalDifficulty =
-        $ecTransitionConfiguration.terminalTotalDifficulty,
-      executionTerminalBlockHash =
-        ecTransitionConfiguration.terminalBlockHash,
-      executionTerminalBlockNumber =
-        ecTransitionConfiguration.terminalBlockNumber.uint64
+      error "Failed to exchange transition configuration", err = err.msg
+      return EtcStatus.exchangeError
+
+  if consensusCfg.terminalTotalDifficulty != executionCfg.terminalTotalDifficulty:
+    warn "Engine API configured with different terminal total difficulty",
+         engineAPI_value = executionCfg.terminalTotalDifficulty,
+         localValue = consensusCfg.terminalTotalDifficulty
+    return EtcStatus.mismatch
+
+  if p.terminalBlockNumber.isSome and p.terminalBlockHash.isSome:
+    var res = EtcStatus.match
+    if consensusCfg.terminalBlockNumber != executionCfg.terminalBlockNumber:
+      warn "Engine API reporting different terminal block number",
+            engineAPI_value = executionCfg.terminalBlockNumber.uint64,
+            localValue = consensusCfg.terminalBlockNumber.uint64
+      res = EtcStatus.mismatch
+    if consensusCfg.terminalBlockHash != executionCfg.terminalBlockHash:
+      warn "Engine API reporting different terminal block hash",
+            engineAPI_value = executionCfg.terminalBlockHash,
+            localValue = consensusCfg.terminalBlockHash
+      res = EtcStatus.mismatch
+    return res
+  else:
+    p.terminalBlockNumber = some executionCfg.terminalBlockNumber
+    p.terminalBlockHash = some executionCfg.terminalBlockHash
+    return EtcStatus.localConfigurationUpdated
 
 template readJsonField(j: JsonNode, fieldName: string, ValueType: type): untyped =
   var res: ValueType
@@ -1037,7 +1053,8 @@ proc init*(T: type Eth1Monitor,
            depositContractSnapshot: Option[DepositContractSnapshot],
            eth1Network: Option[Eth1Network],
            forcePolling: bool,
-           jwtSecret: Option[seq[byte]]): T =
+           jwtSecret: Option[seq[byte]],
+           requireEngineAPI: bool): T =
   doAssert web3Urls.len > 0
   var web3Urls = web3Urls
   for url in mitems(web3Urls):
@@ -1055,7 +1072,8 @@ proc init*(T: type Eth1Monitor,
     eth1Progress: newAsyncEvent(),
     forcePolling: forcePolling,
     jwtSecret: jwtSecret,
-    blocksPerLogsRequest: targetBlocksPerLogsRequest)
+    blocksPerLogsRequest: targetBlocksPerLogsRequest,
+    requireEngineAPI: requireEngineAPI)
 
 proc safeCancel(fut: var Future[void]) =
   if not fut.isNil and not fut.finished:
@@ -1340,6 +1358,20 @@ proc startEth1Syncing(m: Eth1Monitor, delayBeforeStart: Duration) {.async.} =
 
   await m.ensureDataProvider()
 
+  if m.currentEpoch >= m.cfg.BELLATRIX_FORK_EPOCH:
+    let status = await m.exchangeTransitionConfiguration()
+    if status == EtcStatus.localConfigurationUpdated:
+      info "Obtained terminal block from Engine API",
+           terminalBlockNumber = m.terminalBlockNumber.get.uint64,
+           terminalBlockHash = m.terminalBlockHash.get
+    elif status != EtcStatus.match and isFirstRun and m.requireEngineAPI:
+      fatal "The Bellatrix hard fork requires the beacon node to be connected to a properly configured Engine API end-point. " &
+            "See https://nimbus.guide/merge.html for more details. " &
+            "If you want to temporarily continue operating Nimbus without configuring an Engine API end-point, " &
+            "please specify the command-line option --require-engine-api-in-bellatrix=no when launching it. " &
+            "Please note that you MUST complete the migration before the network TTD is reached (estimated to happen near 13th of September)"
+      quit 1
+
   # We might need to reset the chain if the new provider disagrees
   # with the previous one regarding the history of the chain or if
   # we have detected a conensus violation - our view disagreeing with

beacon_chain/nimbus_beacon_node.nim

@@ -538,7 +538,8 @@ proc init*(T: type BeaconNode,
           getDepositContractSnapshot(),
           eth1Network,
           config.web3ForcePolling,
-          optJwtSecret)
+          optJwtSecret,
+          config.requireEngineAPI)
 
         eth1Monitor.loadPersistedDeposits()
 
@@ -639,7 +640,8 @@ proc init*(T: type BeaconNode,
       getDepositContractSnapshot(),
       eth1Network,
       config.web3ForcePolling,
-      optJwtSecret)
+      optJwtSecret,
+      config.requireEngineAPI)
 
   if config.rpcEnabled:
     warn "Nimbus's JSON-RPC server has been removed. This includes the --rpc, --rpc-port, and --rpc-address configuration options. https://nimbus.guide/rest-api.html shows how to enable and configure the REST Beacon API server which replaces it."

beacon_chain/nimbus_light_client.nim

@@ -61,7 +61,8 @@ programMain:
           cfg, db = nil, getBeaconTime, config.web3Urls,
           none(DepositContractSnapshot), metadata.eth1Network,
           forcePolling = false,
-          rng[].loadJwtSecret(config, allowCreate = false))
+          rng[].loadJwtSecret(config, allowCreate = false),
+          true)
         waitFor res.ensureDataProvider()
         res
       else:

docs/the_nimbus_book/src/merge.md

@@ -22,6 +22,8 @@ As a node operator, you will need to run both an execution client and a consensu
 
 If you were running an execution client before, make sure to update its configuration to include an option for [JWT secrets](./eth1.md#3-pass-the-jwt-secret-to-nimbus) and engine API.
 
+Please note that once the Bellatrix fork epoch is reached on 6th of September 2022, Nimbus will refuse to start unless connected to a properly configured execution client. If you need more time to complete the transition, you can temporarily run the beacon node with the command-line option `--require-engine-api-in-bellatrix=no`, but please note that such a setup will stop working once the network TTD is reached (currently estimated to happen on 13th of September, see https://wenmerge.com/ for more up-to-date information).
+
 ### Prepare a suggested fee recipient
 
 After the merge, validators that propose blocks are eligible to recieve transaction fees - read more about fee recipients [here](https://launchpad.ethereum.org/en/merge-readiness#fee-recipient).

scripts/test_merge_node.nim

@@ -59,7 +59,7 @@ proc run() {.async.} =
     eth1Monitor = Eth1Monitor.init(
       defaultRuntimeConfig, db = nil, nil, @[paramStr(1)],
       none(DepositContractSnapshot), none(Eth1Network), false,
-      some readJwtSecret(paramStr(2)).get)
+      some readJwtSecret(paramStr(2)).get, true)
 
   await eth1Monitor.ensureDataProvider()
   try:

scripts/test_merge_vectors.nim

@@ -60,7 +60,8 @@ proc run() {.async.} =
     jwtSecret = some readJwtSecret("jwt.hex").get
     eth1Monitor = Eth1Monitor.init(
       defaultRuntimeConfig, db = nil, nil, @[web3Url],
-      none(DepositContractSnapshot), none(Eth1Network), false, jwtSecret)
+      none(DepositContractSnapshot), none(Eth1Network),
+      false, jwtSecret, true)
     web3Provider = (await Web3DataProvider.new(
       default(Eth1Address), web3Url, jwtSecret)).get