Tidy up and tests for the new class

Signed-off-by: Matthew Whitehead <matthew1001@gmail.com>

besu/src/main/java/org/hyperledger/besu/cli/BesuCommand.java

@@ -1466,12 +1466,13 @@ public void run() {
       vertx = createVertx(createVertxOptions(metricsSystem.get()));
 
       validateOptions();
+
+      performDowngradeCheck();
+
       configure();
       configureNativeLibs();
       besuController = initController();
 
-      performDowngradeCheck();
-
       besuPluginContext.beforeExternalServices();
 
       final var runner = buildRunner();
@@ -1491,6 +1492,14 @@ public void run() {
     }
   }
 
+  /**
+   * This function is designed to protect a Besu instance from being unintentionally started at a lower
+   * version than the previous instance. Doing so could cause unexpected data corruption (depending on
+   * the storage provider that is in use), so this check prompts the user if a downgrade is detected
+   * and requires them to opt-in by setting --allow-downgrade. The --allow-downgrade flag only needs
+   * to be passed in once, and then the version information is updated to the lower version number, meaning
+   * future restarts will pass the check.
+   */
   private void performDowngradeCheck() throws IOException {
     final VersionMetadata versionMetaData = VersionMetadata.lookUpFrom(dataDir());
     if (versionMetaData.getBesuVersion().equals(VersionMetadata.BESU_VERSION_UNKNOWN)) {
@@ -1528,7 +1537,7 @@ private void performDowngradeCheck() throws IOException {
                   + " is lower than version "
                   + metadataVersion
                   + " that last started."
-                  + ". Specify --allow-downgrade to allow Besu to start at the lower version (warning - this may have unrecoverable effects on the database).";
+                  + "Specify --allow-downgrade to allow Besu to start at the lower version (warning - this may have unrecoverable effects on the database).";
           logger.error(message);
           throw new StorageException(message);
         }
@@ -3432,6 +3441,16 @@ String getLogLevel() {
     return loggingLevelOption.getLogLevel();
   }
 
+  /**
+   * Returns the flag indicating that downgrades are allowed.
+   *
+   * @return true if downgrades are allowed, otherwise false
+   */
+  @VisibleForTesting
+  public Boolean getAllowDowngrade() {
+    return allowDowngrade;
+  }
+
   private class BesuCommandConfigurationService implements BesuConfiguration {
 
     @Override

besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java

@@ -1989,19 +1989,6 @@ public void parsesInvalidBonsaiTrieLimitBackLayersOption() {
             "Invalid value for option '--bonsai-maximum-back-layers-to-load': 'ten' is not a long");
   }
 
-  @Test
-  public void parsesValidAllowDowngradeOption() {
-    parseCommand("--allow-dowgrade", "true");
-    verify(mockControllerBuilder)
-        .dataStorageConfiguration(dataStorageConfigurationArgumentCaptor.capture());
-
-    final DataStorageConfiguration dataStorageConfiguration =
-        dataStorageConfigurationArgumentCaptor.getValue();
-    assertThat(dataStorageConfiguration.getAllowDowngrade()).isEqualTo(Boolean.valueOf("true"));
-    assertThat(commandOutput.toString(UTF_8)).isEmpty();
-    assertThat(commandErrorOutput.toString(UTF_8)).isEmpty();
-  }
-
   @Test
   public void dnsEnabledOptionIsParsedCorrectly() {
     final TestBesuCommand besuCommand = parseCommand("--Xdns-enabled", "true");
@@ -2010,6 +1997,13 @@ public void dnsEnabledOptionIsParsedCorrectly() {
     assertThat(besuCommand.getEnodeDnsConfiguration().updateEnabled()).isFalse();
   }
 
+  @Test
+  public void allowDowngradeTrueOptionIsParsedCorrectly() {
+    final TestBesuCommand besuCommand = parseCommand("--allow-downgrade", "true");
+
+    assertThat(besuCommand.getAllowDowngrade()).isTrue();
+  }
+
   @Test
   public void dnsUpdateEnabledOptionIsParsedCorrectly() {
     final TestBesuCommand besuCommand =

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/core/VersionMetadata.java

@@ -1,5 +1,5 @@
 /*
- * Copyright ConsenSys AG.
+ * Copyright Hyperledger Besu contributors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
@@ -29,7 +29,7 @@
 public class VersionMetadata {
   private static final Logger LOG = LoggerFactory.getLogger(VersionMetadata.class);
 
-  /** Represents an unknown Besu version in the database metadata file */
+  /** Represents an unknown Besu version in the version metadata file */
   public static final String BESU_VERSION_UNKNOWN = "UNKNOWN";
 
   private static final String METADATA_FILENAME = "VERSION_METADATA.json";
@@ -56,7 +56,7 @@ public String getBesuVersion() {
 
   public static VersionMetadata lookUpFrom(final Path dataDir) throws IOException {
     LOG.info("Lookup version metadata file in data directory: {}", dataDir.toString());
-    return resolveDatabaseMetadata(getDefaultMetadataFile(dataDir));
+    return resolveVersionMetadata(getDefaultMetadataFile(dataDir));
   }
 
   public void writeToDirectory(final Path dataDir) throws IOException {
@@ -67,18 +67,18 @@ private static File getDefaultMetadataFile(final Path dataDir) {
     return dataDir.resolve(METADATA_FILENAME).toFile();
   }
 
-  private static VersionMetadata resolveDatabaseMetadata(final File metadataFile)
+  private static VersionMetadata resolveVersionMetadata(final File metadataFile)
       throws IOException {
-    VersionMetadata databaseMetadata;
+    VersionMetadata versionMetadata;
     try {
-      databaseMetadata = MAPPER.readValue(metadataFile, VersionMetadata.class);
-      LOG.info("Existing version data detected. Besu version {}", databaseMetadata.besuVersion);
+      versionMetadata = MAPPER.readValue(metadataFile, VersionMetadata.class);
+      LOG.info("Existing version data detected. Besu version {}", versionMetadata.besuVersion);
     } catch (FileNotFoundException fnfe) {
-      databaseMetadata = new VersionMetadata(BESU_VERSION_UNKNOWN);
+      versionMetadata = new VersionMetadata(BESU_VERSION_UNKNOWN);
     } catch (JsonProcessingException jpe) {
       throw new IllegalStateException(
           java.lang.String.format("Invalid metadata file %s", metadataFile.getAbsolutePath()), jpe);
     }
-    return databaseMetadata;
+    return versionMetadata;
   }
 }

ethereum/core/src/test/java/org/hyperledger/besu/ethereum/core/VersionMetadataTest.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright Hyperledger Besu contributors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.hyperledger.besu.ethereum.core;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class VersionMetadataTest {
+  @TempDir public Path temporaryFolder;
+
+  @Test
+  void getVersion() {
+    final VersionMetadata versionMetadata = new VersionMetadata("23.10.2");
+    assertThat(versionMetadata).isNotNull();
+    assertThat(versionMetadata.getBesuVersion()).isEqualTo("23.10.2");
+  }
+
+  @Test
+  void metaFileShouldContain() throws Exception {
+    final Path tempDataDir =
+        createAndWrite("data", "VERSION_METADATA.json", "{\"besuVersion\":\"23.10.3\"}");
+
+    final VersionMetadata versionMetadata = VersionMetadata.lookUpFrom(tempDataDir);
+    assertThat(versionMetadata).isNotNull();
+    assertThat(versionMetadata.getBesuVersion()).isEqualTo("23.10.3");
+  }
+
+  private Path createAndWrite(final String dir, final String file, final String content)
+      throws IOException {
+    return createAndWrite(temporaryFolder, dir, file, content);
+  }
+
+  private Path createAndWrite(
+      final Path temporaryFolder, final String dir, final String file, final String content)
+      throws IOException {
+    final Path tmpDir = temporaryFolder.resolve(dir);
+    Files.createDirectories(tmpDir);
+    createAndWrite(tmpDir.resolve(file), content);
+    return tmpDir;
+  }
+
+  private void createAndWrite(final Path path, final String content) throws IOException {
+    path.toFile().createNewFile();
+    Files.writeString(path, content);
+  }
+}

plugin-api/src/main/java/org/hyperledger/besu/plugin/services/BesuService.java

@@ -21,14 +21,4 @@
  * All services that can be resolved via {@link BesuContext#getService(Class)} must implement {@link
  * BesuService}
  */
-public interface BesuService {
-
-  /**
-   * Get the version of Besu that is running.
-   *
-   * @return the version of Besu
-   */
-  default String getBesuVersion() {
-    return BesuService.class.getPackage().getImplementationVersion();
-  }
-}
+public interface BesuService {}