Factor away some complexity of withBFTNode

Also left a FIXME about the wrong promises made by the function name and
its arguments.

hydra-cluster/src/CardanoNode.hs

@@ -112,25 +112,28 @@ getCardanoNodeVersion =
   readProcess "cardano-node" ["--version"] ""
 
 -- | Start a cardano-node in BFT mode using the config from config/ and
--- credentials from config/credentials/ using given 'nodeId'. NOTE: This means
--- that nodeId should only be 1,2 or 3 and that only the faucet receives
--- 'initialFunds'. Use 'seedFromFaucet' to distribute funds other wallets.
+-- credentials from config/credentials/ using given 'nodeId'. Only the 'Faucet'
+-- actor will receive "initialFunds". Use 'seedFromFaucet' to distribute funds
+-- other wallets.
+--
+-- FIXME: This is actually not a BFT node and it also only supports nodeId == 1.
+-- We should rename this function and also think about removing the `nodeId`
+-- from `CardanoNodeConfig` as it is a lie.
 withBFTNode ::
   Tracer IO NodeLog ->
   CardanoNodeConfig ->
   (RunningNode -> IO ()) ->
   IO ()
 withBFTNode tracer cfg action = do
-  createDirectoryIfMissing False (stateDirectory cfg)
-  createDirectoryIfMissing False (stateDirectory cfg </> dirname (nodeId cfg))
+  createDirectoryIfMissing True (stateDirectory cfg </> dirname)
 
   [dlgCert, signKey, vrfKey, kesKey, opCert] <-
     forM
-      [ dlgCertFilename (nodeId cfg)
-      , signKeyFilename (nodeId cfg)
-      , vrfKeyFilename (nodeId cfg)
-      , kesKeyFilename (nodeId cfg)
-      , opCertFilename (nodeId cfg)
+      [ dlgCertFilename
+      , signKeyFilename
+      , vrfKeyFilename
+      , kesKeyFilename
+      , opCertFilename
       ]
       (copyCredential (stateDirectory cfg))
 
@@ -166,19 +169,19 @@ withBFTNode tracer cfg action = do
     traceWith tracer $ MsgSocketIsReady socket
     action rn
  where
-  dirname i =
-    "stake-pool-" <> show i
-
-  dlgCertFilename i =
-    dirname i </> "byron-delegation.cert"
-  signKeyFilename i =
-    dirname i </> "byron-delegate.key"
-  vrfKeyFilename i =
-    dirname i </> "vrf.skey"
-  kesKeyFilename i =
-    dirname i </> "kes.skey"
-  opCertFilename i =
-    dirname i </> "opcert.cert"
+  dirname =
+    "stake-pool-" <> show (nodeId cfg)
+
+  dlgCertFilename =
+    dirname </> "byron-delegation.cert"
+  signKeyFilename =
+    dirname </> "byron-delegate.key"
+  vrfKeyFilename =
+    dirname </> "vrf.skey"
+  kesKeyFilename =
+    dirname </> "kes.skey"
+  opCertFilename =
+    dirname </> "opcert.cert"
 
   copyCredential parentDir file = do
     bs <- readConfigFile ("credentials" </> file)