Configure Undertow's access log prefix and suffix

This commit adds two properties that can be used to customize the prefix
and suffix of the Undertow's access log.

Closes gh-6652

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ServerProperties.java

@@ -1270,6 +1270,12 @@ public class ServerProperties
 			if (this.accesslog.pattern != null) {
 				factory.setAccessLogPattern(this.accesslog.pattern);
 			}
+			if (this.accesslog.prefix != null) {
+				factory.setAccessLogPrefix(this.accesslog.prefix);
+			}
+			if (this.accesslog.suffix != null) {
+				factory.setAccessLogSuffix(this.accesslog.suffix);
+			}
 			if (this.accesslog.enabled != null) {
 				factory.setAccessLogEnabled(this.accesslog.enabled);
 			}
@@ -1340,6 +1346,16 @@ public class ServerProperties
 			 */
 			private String pattern = "common";
 
+			/**
+			 * Log file name prefix.
+			 */
+			protected String prefix = "access_log.";
+
+			/**
+			 * Log file name suffix.
+			 */
+			private String suffix = "log";
+
 			/**
 			 * Undertow access log directory.
 			 */
@@ -1361,6 +1377,22 @@ public class ServerProperties
 				this.pattern = pattern;
 			}
 
+			public String getPrefix() {
+				return this.prefix;
+			}
+
+			public void setPrefix(String prefix) {
+				this.prefix = prefix;
+			}
+
+			public String getSuffix() {
+				return this.suffix;
+			}
+
+			public void setSuffix(String suffix) {
+				this.suffix = suffix;
+			}
+
 			public File getDir() {
 				return this.dir;
 			}

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -219,6 +219,8 @@ content into your application; rather pick only the properties that you need.
 	server.undertow.accesslog.dir= # Undertow access log directory.
 	server.undertow.accesslog.enabled=false # Enable access log.
 	server.undertow.accesslog.pattern=common # Format pattern for access logs.
+	server.undertow.accesslog.prefix=access_log. # Log file name prefix.
+	server.undertow.accesslog.suffix=log # Log file name suffix.
 	server.undertow.buffer-size= # Size of each buffer in bytes.
 	server.undertow.buffers-per-region= # Number of buffer per region.
 	server.undertow.direct-buffers= # Allocate buffers outside the Java heap.

spring-boot/src/main/java/org/springframework/boot/context/embedded/undertow/UndertowEmbeddedServletContainerFactory.java

@@ -122,6 +122,10 @@ public class UndertowEmbeddedServletContainerFactory
 
 	private String accessLogPattern;
 
+	private String accessLogPrefix;
+
+	private String accessLogSuffix;
+
 	private boolean accessLogEnabled = false;
 
 	private boolean useForwardHeaders;
@@ -408,8 +412,9 @@ public class UndertowEmbeddedServletContainerFactory
 	private AccessLogHandler createAccessLogHandler(HttpHandler handler) {
 		try {
 			createAccessLogDirectoryIfNecessary();
+			String prefix = (this.accessLogPrefix != null ? this.accessLogPrefix : "access_log.");
 			AccessLogReceiver accessLogReceiver = new DefaultAccessLogReceiver(
-					createWorker(), this.accessLogDirectory, "access_log.");
+					createWorker(), this.accessLogDirectory, prefix, this.accessLogSuffix);
 			String formatString = (this.accessLogPattern != null) ? this.accessLogPattern
 					: "common";
 			return new AccessLogHandler(handler, accessLogReceiver, formatString,
@@ -561,6 +566,14 @@ public class UndertowEmbeddedServletContainerFactory
 		this.accessLogPattern = accessLogPattern;
 	}
 
+	public void setAccessLogPrefix(String accessLogPrefix) {
+		this.accessLogPrefix = accessLogPrefix;
+	}
+
+	public void setAccessLogSuffix(String accessLogSuffix) {
+		this.accessLogSuffix = accessLogSuffix;
+	}
+
 	public void setAccessLogEnabled(boolean accessLogEnabled) {
 		this.accessLogEnabled = accessLogEnabled;
 	}

spring-boot/src/test/java/org/springframework/boot/context/embedded/undertow/UndertowEmbeddedServletContainerFactoryTests.java

@@ -178,8 +178,21 @@ public class UndertowEmbeddedServletContainerFactoryTests
 	@Test
 	public void accessLogCanBeEnabled()
 			throws IOException, URISyntaxException, InterruptedException {
+		testAccessLog(null, null, "access_log.log");
+	}
+
+	@Test
+	public void accessLogCanBeCustomized()
+			throws IOException, URISyntaxException, InterruptedException {
+		testAccessLog("my_access.", "logz", "my_access.logz");
+	}
+
+	private void testAccessLog(String prefix, String suffix, String expectedFile)
+			throws IOException, URISyntaxException, InterruptedException {
 		UndertowEmbeddedServletContainerFactory factory = getFactory();
 		factory.setAccessLogEnabled(true);
+		factory.setAccessLogPrefix(prefix);
+		factory.setAccessLogSuffix(suffix);
 		File accessLogDirectory = this.temporaryFolder.getRoot();
 		factory.setAccessLogDirectory(accessLogDirectory);
 		assertThat(accessLogDirectory.listFiles()).isEmpty();
@@ -187,7 +200,7 @@ public class UndertowEmbeddedServletContainerFactoryTests
 				new ServletRegistrationBean(new ExampleServlet(), "/hello"));
 		this.container.start();
 		assertThat(getResponse(getLocalUrl("/hello"))).isEqualTo("Hello World");
-		File accessLog = new File(accessLogDirectory, "access_log.log");
+		File accessLog = new File(accessLogDirectory, expectedFile);
 		awaitFile(accessLog);
 		assertThat(accessLogDirectory.listFiles()).contains(accessLog);
 	}