[MINOR] node private key location should be fixed under docker

pantheon/src/main/java/tech/pegasys/pantheon/cli/PantheonCommand.java

@@ -146,14 +146,6 @@ public static class RpcApisConversionException extends Exception {
   // CLI options defined by user at runtime.
   // Options parsing is done with CLI library Picocli https://picocli.info/
 
-  @Option(
-    names = {"--node-private-key-file"},
-    paramLabel = MANDATORY_PATH_FORMAT_HELP,
-    description =
-        "the path to the node's private key file (default: a file named \"key\" in the Pantheon data folder)"
-  )
-  private final File nodePrivateKeyFile = null;
-
   // Completely disables p2p within Pantheon.
   @Option(
     names = {"--p2p-enabled"},
@@ -633,7 +625,7 @@ PantheonController<?> buildController() {
           .miningParameters(
               new MiningParameters(coinbase, minTransactionGasPrice, extraData, isMiningEnabled))
           .devMode(NetworkName.DEV.equals(getNetwork()))
-          .nodePrivateKeyFile(getNodePrivateKeyFile())
+          .nodePrivateKeyFile(nodePrivateKeyFile())
           .metricsSystem(metricsSystem)
           .privacyParameters(orionConfiguration())
           .build();
@@ -644,12 +636,6 @@ PantheonController<?> buildController() {
     }
   }
 
-  private File getNodePrivateKeyFile() {
-    return nodePrivateKeyFile != null
-        ? nodePrivateKeyFile
-        : KeyPairUtil.getDefaultKeyFile(dataDir());
-  }
-
   private JsonRpcConfiguration jsonRpcConfiguration() {
 
     CommandLineUtils.checkOptionDependencies(
@@ -942,6 +928,17 @@ private Path dataDir() {
     }
   }
 
+  private File nodePrivateKeyFile() {
+    File nodePrivateKeyFile = null;
+    if (isFullInstantiation()) {
+      nodePrivateKeyFile = standaloneCommands.nodePrivateKeyFile;
+    }
+
+    return nodePrivateKeyFile != null
+        ? nodePrivateKeyFile
+        : KeyPairUtil.getDefaultKeyFile(dataDir());
+  }
+
   private boolean isFullInstantiation() {
     return !isDocker;
   }

pantheon/src/main/java/tech/pegasys/pantheon/cli/StandaloneCommand.java

@@ -47,4 +47,12 @@ class StandaloneCommand implements DefaultCommandValues {
         "The path to genesis file. Setting this option makes --network option ignored and requires --network-id to be set."
   )
   final File genesisFile = null;
+
+  @CommandLine.Option(
+    names = {"--node-private-key-file"},
+    paramLabel = MANDATORY_PATH_FORMAT_HELP,
+    description =
+        "the path to the node's private key file (default: a file named \"key\" in the Pantheon data folder)"
+  )
+  final File nodePrivateKeyFile = null;
 }

pantheon/src/test/java/tech/pegasys/pantheon/cli/PantheonCommandTest.java

@@ -416,6 +416,33 @@ public void nodekeyOptionMustBeUsed() throws Exception {
     assertThat(commandErrorOutput.toString()).isEmpty();
   }
 
+  @Test
+  public void nodekeyOptionDisabledUnderDocker() {
+    System.setProperty("pantheon.docker", "true");
+
+    assumeFalse(isFullInstantiation());
+
+    final File file = new File("./specific/key");
+
+    parseCommand("--node-private-key-file", file.getPath());
+
+    assertThat(commandErrorOutput.toString())
+        .startsWith("Unknown options: --node-private-key-file, .");
+    assertThat(commandOutput.toString()).isEmpty();
+  }
+
+  @Test
+  public void nodekeyDefaultedUnderDocker() {
+    System.setProperty("pantheon.docker", "true");
+
+    assumeFalse(isFullInstantiation());
+
+    parseCommand();
+
+    verify(mockControllerBuilder).nodePrivateKeyFile(fileArgumentCaptor.capture());
+    assertThat(fileArgumentCaptor.getValue()).isEqualTo(new File("/var/lib/pantheon/key"));
+  }
+
   @Test
   public void dataDirOptionMustBeUsed() throws Exception {
     assumeTrue(isFullInstantiation());