Log4j2: Add property-driven rolling strategy support and metadata

      - Introduce rolling policy properties: strategy, time-based.interval, time-based.modulate, cron.schedule
      - Extend Log4j2RollingPolicySystemProperty with STRATEGY, TIME_INTERVAL, TIME_MODULATE, CRON_SCHEDULE
      - Propagate new properties in Log4j2LoggingSystemProperties (with deprecated fallback guarded for null)
      - Document new properties in configuration metadata
      - Update Log4j2LoggingSystemPropertiesTests to assert new system properties mappingAdd Log4j2 rolling policy configuration support

Signed-off-by: hojooo <[email protected]>

Author: hojooo

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/Log4j2LoggingSystemProperties.java

@@ -71,6 +71,10 @@ protected void apply(@Nullable LogFile logFile, PropertyResolver resolver) {
 	}
 
 	private void applyRollingPolicyProperties(PropertyResolver resolver) {
+		applyRollingPolicy(Log4j2RollingPolicySystemProperty.STRATEGY, resolver);
+		applyRollingPolicy(Log4j2RollingPolicySystemProperty.TIME_INTERVAL, resolver, Integer.class);
+		applyRollingPolicy(Log4j2RollingPolicySystemProperty.TIME_MODULATE, resolver, Boolean.class);
+		applyRollingPolicy(Log4j2RollingPolicySystemProperty.CRON_SCHEDULE, resolver);
 		applyRollingPolicy(Log4j2RollingPolicySystemProperty.FILE_NAME_PATTERN, resolver);
 		applyRollingPolicy(Log4j2RollingPolicySystemProperty.CLEAN_HISTORY_ON_START, resolver);
 		applyRollingPolicy(Log4j2RollingPolicySystemProperty.MAX_FILE_SIZE, resolver, DataSize.class);
@@ -85,7 +89,9 @@ private void applyRollingPolicy(Log4j2RollingPolicySystemProperty property, Prop
 	private <T> void applyRollingPolicy(Log4j2RollingPolicySystemProperty property, PropertyResolver resolver,
 			Class<T> type) {
 		T value = getProperty(resolver, property.getApplicationPropertyName(), type);
-		value = (value != null) ? value : getProperty(resolver, property.getDeprecatedApplicationPropertyName(), type);
+		if (value == null && property.getDeprecatedApplicationPropertyName() != null) {
+			value = getProperty(resolver, property.getDeprecatedApplicationPropertyName(), type);
+		}
 		if (value != null) {
 			String stringValue = String.valueOf((value instanceof DataSize dataSize) ? dataSize.toBytes() : value);
 			setSystemProperty(property.getEnvironmentVariableName(), stringValue);

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/Log4j2RollingPolicySystemProperty.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.logging.log4j2;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Log4j2 rolling policy system properties that can later be used by log configuration
  * files.
@@ -48,15 +50,35 @@ public enum Log4j2RollingPolicySystemProperty {
 	/**
 	 * Logging system property for the file log max history.
 	 */
-	MAX_HISTORY("max-history", "logging.file.max-history");
+	MAX_HISTORY("max-history", "logging.file.max-history"),
+
+	/**
+	 * Logging system property for the rolling policy strategy.
+	 */
+	STRATEGY("strategy", null),
+
+	/**
+	 * Logging system property for the rolling policy time interval.
+	 */
+	TIME_INTERVAL("time-based.interval", null),
+
+	/**
+	 * Logging system property for the rolling policy time modulate flag.
+	 */
+	TIME_MODULATE("time-based.modulate", null),
+
+	/**
+	 * Logging system property for the cron based schedule.
+	 */
+	CRON_SCHEDULE("cron.schedule", null);
 
 	private final String environmentVariableName;
 
 	private final String applicationPropertyName;
 
-	private final String deprecatedApplicationPropertyName;
+	private final @Nullable String deprecatedApplicationPropertyName;
 
-	Log4j2RollingPolicySystemProperty(String applicationPropertyName, String deprecatedApplicationPropertyName) {
+	Log4j2RollingPolicySystemProperty(String applicationPropertyName, @Nullable String deprecatedApplicationPropertyName) {
 		this.environmentVariableName = "LOG4J2_ROLLINGPOLICY_" + name();
 		this.applicationPropertyName = "logging.log4j2.rollingpolicy." + applicationPropertyName;
 		this.deprecatedApplicationPropertyName = deprecatedApplicationPropertyName;
@@ -74,7 +96,7 @@ String getApplicationPropertyName() {
 		return this.applicationPropertyName;
 	}
 
-	String getDeprecatedApplicationPropertyName() {
+	@Nullable String getDeprecatedApplicationPropertyName() {
 		return this.deprecatedApplicationPropertyName;
 	}
 

core/spring-boot/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -141,6 +141,33 @@
       "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener",
       "defaultValue": false
     },
+    {
+      "name": "logging.log4j2.rollingpolicy.strategy",
+      "type": "java.lang.String",
+      "description": "Rolling policy strategy. Supported values are 'size', 'time', 'size-and-time', and 'cron'.",
+      "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener",
+      "defaultValue": "size"
+    },
+    {
+      "name": "logging.log4j2.rollingpolicy.time-based.interval",
+      "type": "java.lang.Integer",
+      "description": "Time based triggering interval when the strategy is 'time' or 'size-and-time'.",
+      "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener",
+      "defaultValue": 1
+    },
+    {
+      "name": "logging.log4j2.rollingpolicy.time-based.modulate",
+      "type": "java.lang.Boolean",
+      "description": "Whether to align the next rollover time to occur at the top of the interval when the strategy is time based.",
+      "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener",
+      "defaultValue": false
+    },
+    {
+      "name": "logging.log4j2.rollingpolicy.cron.schedule",
+      "type": "java.lang.String",
+      "description": "Cron expression used when the strategy is 'cron'.",
+      "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener"
+    },
     {
       "name": "logging.log4j2.rollingpolicy.file-name-pattern",
       "type": "java.lang.String",

core/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4j2LoggingSystemPropertiesTests.java

@@ -52,9 +52,11 @@ void appliesLog4j2RollingPolicyProperties() {
 		Environment environment = new StandardEnvironment();
 		addPropertiesToEnvironment(environment, "logging.log4j2.rollingpolicy.max-file-size", "50MB",
 				"logging.log4j2.rollingpolicy.clean-history-on-start", "true",
-				"logging.log4j2.rollingpolicy.max-history", "30",
-				"logging.log4j2.rollingpolicy.total-size-cap", "10GB",
-				"logging.log4j2.rollingpolicy.file-name-pattern", "test.%d{yyyy-MM-dd}.%i.log");
+				"logging.log4j2.rollingpolicy.max-history", "30", "logging.log4j2.rollingpolicy.total-size-cap", "10GB",
+				"logging.log4j2.rollingpolicy.file-name-pattern", "test.%d{yyyy-MM-dd}.%i.log",
+				"logging.log4j2.rollingpolicy.strategy", "time", "logging.log4j2.rollingpolicy.time-based.interval",
+				"2", "logging.log4j2.rollingpolicy.time-based.modulate", "true",
+				"logging.log4j2.rollingpolicy.cron.schedule", "0 0 0 * * ?");
 		new Log4j2LoggingSystemProperties(environment, this.systemPropertySetter).apply(null);
 		assertThat(this.systemProperties).containsEntry("LOG4J2_ROLLINGPOLICY_MAX_FILE_SIZE",
 				String.valueOf(DataSize.ofMegabytes(50).toBytes()));
@@ -64,6 +66,10 @@ void appliesLog4j2RollingPolicyProperties() {
 				String.valueOf(DataSize.ofGigabytes(10).toBytes()));
 		assertThat(this.systemProperties).containsEntry("LOG4J2_ROLLINGPOLICY_FILE_NAME_PATTERN",
 				"test.%d{yyyy-MM-dd}.%i.log");
+		assertThat(this.systemProperties).containsEntry("LOG4J2_ROLLINGPOLICY_STRATEGY", "time");
+		assertThat(this.systemProperties).containsEntry("LOG4J2_ROLLINGPOLICY_TIME_INTERVAL", "2");
+		assertThat(this.systemProperties).containsEntry("LOG4J2_ROLLINGPOLICY_TIME_MODULATE", "true");
+		assertThat(this.systemProperties).containsEntry("LOG4J2_ROLLINGPOLICY_CRON_SCHEDULE", "0 0 0 * * ?");
 	}
 
 	@Test
@@ -111,8 +117,7 @@ private void addPropertiesToEnvironment(Environment environment, String... pairs
 		for (int i = 0; i < pairs.length; i += 2) {
 			map.put(pairs[i], pairs[i + 1]);
 		}
-		((StandardEnvironment) environment).getPropertySources()
-			.addFirst(new MapPropertySource("test", map));
+		((StandardEnvironment) environment).getPropertySources().addFirst(new MapPropertySource("test", map));
 	}
 
-}
+}