Fix argument to be optional.

beacon_chain/conf.nim

@@ -163,7 +163,7 @@ type
 
     validatorsSource* {.
       desc: "Remote Web3Signer URL that will be used as a source of validators"
-      name: "validators-source"}: string
+      name: "validators-source"}: Option[string]
 
     secretsDirFlag* {.
       desc: "A directory containing validator keystore passwords"
@@ -881,7 +881,7 @@ type
 
     validatorsSource* {.
       desc: "Remote Web3Signer URL that will be used as a source of validators"
-      name: "validators-source"}: string
+      name: "validators-source"}: Option[string]
 
     secretsDirFlag* {.
       desc: "A directory containing validator keystore passwords"

beacon_chain/validators/keystore_management.nim

@@ -630,24 +630,27 @@ proc existsKeystore(keystoreDir: string,
 proc queryValidatorsSource*(config: AnyConf): Future[seq[KeystoreData]] {.
      async.} =
   var keystores: seq[KeystoreData]
-  if len(config.validatorsSource) == 0:
+  if config.validatorsSource.isNone() or
+     len(config.validatorsSource.get()) == 0:
     return keystores
 
+  let vsource = config.validatorsSource.get()
+  logScope:
+    validators_source = vsource
+
   let
     httpFlags: HttpClientFlags = {}
     prestoFlags = {RestClientFlag.CommaSeparatedArray}
     socketFlags = {SocketFlags.TcpNoDelay}
     client =
       block:
-        let res = RestClientRef.new(config.validatorsSource, prestoFlags,
+        let res = RestClientRef.new(vsource, prestoFlags,
                                     httpFlags, socketFlags = socketFlags)
         if res.isErr():
           # TODO keep trying in case of temporary network failure
-          warn "Unable to resolve validator's source distributed signer " &
-               "address", remote_url = config.validatorsSource
+          warn "Unable to resolve validator's source distributed signer address"
           return keystores
-        else:
-          res.get()
+        res.get()
     keys =
       try:
         let response = await getKeysPlain(client)
@@ -681,7 +684,7 @@ proc queryValidatorsSource*(config: AnyConf): Future[seq[KeystoreData]] {.
       handle: FileLockHandle(opened: false),
       pubkey: pubkey,
       remotes: @[RemoteSignerInfo(
-        url: HttpHostUri(parseUri(config.validatorsSource)),
+        url: HttpHostUri(parseUri(vsource)),
         pubkey: pubkey)],
       flags: {RemoteKeystoreFlag.DynamicKeystore},
       remoteType: RemoteSignerType.Web3Signer))