Apply SystemProperties to LoggerContext

Update `LoggingSystemProperties` so that system environment properties
are also applied to the `LoggerContext`. This is required when multiple
applications are deployed to the same Servlet container. In such setups
there's only a single JVM and the System Environment can be changed
when multiple applications start at the same time.

Fixes gh-24835

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/LoggingSystemProperties.java

 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@ package org.springframework.boot.logging;
 
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
+import java.util.function.BiConsumer;
 
 import org.springframework.boot.system.ApplicationPid;
 import org.springframework.core.env.ConfigurableEnvironment;
@@ -130,15 +131,35 @@ public class LoggingSystemProperties {
 	 */
 	public static final String LOG_DATEFORMAT_PATTERN = "LOG_DATEFORMAT_PATTERN";
 
+	private static final BiConsumer<String, String> systemPropertySetter = (name, value) -> {
+		if (System.getProperty(name) == null && value != null) {
+			System.setProperty(name, value);
+		}
+	};
+
 	private final Environment environment;
 
+	private final BiConsumer<String, String> setter;
+
 	/**
 	 * Create a new {@link LoggingSystemProperties} instance.
 	 * @param environment the source environment
 	 */
 	public LoggingSystemProperties(Environment environment) {
+		this(environment, systemPropertySetter);
+	}
+
+	/**
+	 * Create a new {@link LoggingSystemProperties} instance.
+	 * @param environment the source environment
+	 * @param setter setter used to apply the property
+	 * @since 2.4.2
+	 */
+	public LoggingSystemProperties(Environment environment, BiConsumer<String, String> setter) {
 		Assert.notNull(environment, "Environment must not be null");
+		Assert.notNull(setter, "Setter must not be null");
 		this.environment = environment;
+		this.setter = setter;
 	}
 
 	protected Charset getDefaultCharset() {
@@ -200,9 +221,7 @@ public class LoggingSystemProperties {
 	}
 
 	protected final void setSystemProperty(String name, String value) {
-		if (System.getProperty(name) == null && value != null) {
-			System.setProperty(name, value);
-		}
+		this.setter.accept(name, value);
 	}
 
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackLoggingSystem.java

 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -146,15 +146,11 @@ public class LogbackLoggingSystem extends Slf4JLoggingSystem {
 		if (debug) {
 			StatusListenerConfigHelper.addOnConsoleListenerInstance(context, new OnConsoleStatusListener());
 		}
+		Environment environment = initializationContext.getEnvironment();
+		// Apply system properties directly in case the same JVM runs multiple apps
+		new LoggingSystemProperties(environment, context::putProperty).apply(logFile);
 		LogbackConfigurator configurator = debug ? new DebugLogbackConfigurator(context)
 				: new LogbackConfigurator(context);
-		Environment environment = initializationContext.getEnvironment();
-		context.putProperty(LoggingSystemProperties.LOG_LEVEL_PATTERN,
-				environment.resolvePlaceholders("${logging.pattern.level:${LOG_LEVEL_PATTERN:%5p}}"));
-		context.putProperty(LoggingSystemProperties.LOG_DATEFORMAT_PATTERN, environment.resolvePlaceholders(
-				"${logging.pattern.dateformat:${LOG_DATEFORMAT_PATTERN:yyyy-MM-dd HH:mm:ss.SSS}}"));
-		context.putProperty(LoggingSystemProperties.ROLLING_FILE_NAME_PATTERN, environment
-				.resolvePlaceholders("${logging.pattern.rolling-file-name:${LOG_FILE}.%d{yyyy-MM-dd}.%i.gz}"));
 		new DefaultLogbackConfiguration(initializationContext, logFile).apply(configurator);
 		context.setPackagingDataEnabled(true);
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemTests.java

 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,7 +20,9 @@ import java.io.File;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.EnumSet;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.logging.Handler;
 import java.util.logging.LogManager;
 
@@ -87,10 +89,13 @@ class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 
 	private LoggingInitializationContext initializationContext;
 
+	private Set<Object> systemPropertyNames;
+
 	@BeforeEach
 	void setup() {
 		System.getProperties().remove(LoggingSystemProperties.CONSOLE_LOG_CHARSET);
 		System.getProperties().remove(LoggingSystemProperties.FILE_LOG_CHARSET);
+		this.systemPropertyNames = new HashSet<>(System.getProperties().keySet());
 		this.loggingSystem.cleanUp();
 		this.logger = ((LoggerContext) StaticLoggerBinder.getSingleton().getLoggerFactory()).getLogger(getClass());
 		this.environment = new MockEnvironment();
@@ -101,6 +106,7 @@ class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 
 	@AfterEach
 	void cleanUp() {
+		System.getProperties().keySet().retainAll(this.systemPropertyNames);
 		this.loggingSystem.cleanUp();
 		((LoggerContext) StaticLoggerBinder.getSingleton().getLoggerFactory()).stop();
 	}
@@ -312,6 +318,7 @@ class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 	@Test
 	void testLevelPatternProperty(CapturedOutput output) {
 		this.environment.setProperty("logging.pattern.level", "X%clr(%p)X");
+		new LoggingSystemProperties(this.environment).apply();
 		LoggingInitializationContext loggingInitializationContext = new LoggingInitializationContext(this.environment);
 		initialize(loggingInitializationContext, null, null);
 		this.logger.info("Hello world");
@@ -513,6 +520,19 @@ class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 
 	@Test
 	void testDateformatPatternProperty(CapturedOutput output) {
+		this.environment.setProperty("logging.pattern.dateformat", "yyyy-MM-dd'T'hh:mm:ss.SSSZ");
+		new LoggingSystemProperties(this.environment).apply();
+		LoggingInitializationContext loggingInitializationContext = new LoggingInitializationContext(this.environment);
+		initialize(loggingInitializationContext, null, null);
+		this.logger.info("Hello world");
+		assertThat(getLineWithText(output, "Hello world"))
+				.containsPattern("\\d{4}-\\d{2}\\-\\d{2}T\\d{2}:\\d{2}:\\d{2}");
+	}
+
+	@Test // gh-24835
+	void testDateformatPatternPropertyDirect(CapturedOutput output) {
+		this.environment.setProperty("logging.pattern.dateformat", "yyyy'T'hh:mm:ss.SSSZ");
+		new LoggingSystemProperties(this.environment).apply();
 		this.environment.setProperty("logging.pattern.dateformat", "yyyy-MM-dd'T'hh:mm:ss.SSSZ");
 		LoggingInitializationContext loggingInitializationContext = new LoggingInitializationContext(this.environment);
 		initialize(loggingInitializationContext, null, null);