[PAN-2798] Enable pruning by default for fast sync

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

@@ -587,10 +587,9 @@ void setBannedNodeIds(final List<String> values) {
 
   @Option(
       names = {"--pruning-enabled"},
-      hidden = true,
       description =
-          "Enable pruning of world state of blocks older than the retention period (default: ${DEFAULT-VALUE})")
-  private final Boolean isPruningEnabled = false;
+          "Enable pruning of world state of blocks older than the retention period (default: true if fast sync is enabled, false otherwise)")
+  private Boolean pruningOverride;
 
   @Option(
       names = {"--pruning-blocks-retained"},
@@ -1012,7 +1011,7 @@ private void issueOptionWarnings() {
         logger,
         commandLine,
         "--pruning-enabled",
-        !isPruningEnabled,
+        !isPruningEnabled(),
         asList("--pruning-block-confirmations", "--pruning-blocks-retained"));
   }
 
@@ -1088,7 +1087,7 @@ public BesuControllerBuilder<?> getControllerBuilder() {
           .clock(Clock.systemUTC())
           .isRevertReasonEnabled(isRevertReasonEnabled)
           .storageProvider(keyStorageProvider(keyValueStorageName))
-          .isPruningEnabled(isPruningEnabled)
+          .isPruningEnabled(isPruningEnabled())
           .pruningConfiguration(buildPruningConfiguration())
           .genesisConfigOverrides(genesisConfigOverrides)
           .targetGasLimit(targetGasLimit == null ? Optional.empty() : Optional.of(targetGasLimit))
@@ -1375,6 +1374,10 @@ private PruningConfiguration buildPruningConfiguration() {
     return new PruningConfiguration(pruningBlockConfirmations, pruningBlocksRetained);
   }
 
+  private boolean isPruningEnabled() {
+    return Optional.ofNullable(pruningOverride).orElse(syncMode == SyncMode.FAST);
+  }
+
   // Blockchain synchronisation from peers.
   private void synchronize(
       final BesuController<?> controller,

besu/src/main/java/org/hyperledger/besu/controller/BesuControllerBuilder.java

@@ -159,8 +159,8 @@ public BesuControllerBuilder<C> isRevertReasonEnabled(final boolean isRevertReas
     return this;
   }
 
-  public BesuControllerBuilder<C> isPruningEnabled(final boolean pruningEnabled) {
-    this.isPruningEnabled = pruningEnabled;
+  public BesuControllerBuilder<C> isPruningEnabled(final boolean isPruningEnabled) {
+    this.isPruningEnabled = isPruningEnabled;
     return this;
   }
 

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

@@ -2327,7 +2327,29 @@ public void miningParametersAreCaptured() throws Exception {
   }
 
   @Test
-  public void pruningIsEnabledWhenSpecified() throws Exception {
+  public void pruningIsEnabledIfSyncModeIsFast() {
+    parseCommand("--sync-mode", "FAST");
+
+    verify(mockControllerBuilder).isPruningEnabled(true);
+    verify(mockControllerBuilder).build();
+
+    assertThat(commandOutput.toString()).isEmpty();
+    assertThat(commandErrorOutput.toString()).isEmpty();
+  }
+
+  @Test
+  public void pruningIsDisabledIfSyncModeIsFull() {
+    parseCommand("--sync-mode", "FULL");
+
+    verify(mockControllerBuilder).isPruningEnabled(false);
+    verify(mockControllerBuilder).build();
+
+    assertThat(commandOutput.toString()).isEmpty();
+    assertThat(commandErrorOutput.toString()).isEmpty();
+  }
+
+  @Test
+  public void pruningEnabledExplicitly() {
     parseCommand("--pruning-enabled");
 
     verify(mockControllerBuilder).isPruningEnabled(true);
@@ -2337,6 +2359,17 @@ public void pruningIsEnabledWhenSpecified() throws Exception {
     assertThat(commandErrorOutput.toString()).isEmpty();
   }
 
+  @Test
+  public void pruningDisabledExplicitly() {
+    parseCommand("--pruning-enabled=false");
+
+    verify(mockControllerBuilder).isPruningEnabled(false);
+    verify(mockControllerBuilder).build();
+
+    assertThat(commandOutput.toString()).isEmpty();
+    assertThat(commandErrorOutput.toString()).isEmpty();
+  }
+
   @Test
   public void pruningOptionsRequiresServiceToBeEnabled() {
 

besu/src/test/resources/everything_config.toml

@@ -83,6 +83,9 @@ miner-coinbase="0x0000000000000000000000000000000000000002"
 miner-extra-data="0x444F4E27542050414E4943202120484F444C2C20484F444C2C20484F444C2021"
 min-gas-price=1
 
+# Pruning
+pruning-enabled=true
+
 # Permissioning
 permissions-nodes-config-file-enabled=false
 permissions-nodes-config-file="./permissions_config.toml"