Add external-file-property to LogFileMvcEndpoint

Add an additional property to LogFileMvcEndpoint to allow log files to
be read from an external location. This is helpful when a launch.script
is used to start the boot-application and the logfile is written by a
redirect of stdout/stderr.

Fixes gh-4255
Closes gh-4836

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/EndpointWebMvcManagementContextConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -40,6 +40,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ConditionContext;
@@ -180,6 +181,12 @@ public class EndpointWebMvcManagementContextConfiguration {
 			if (StringUtils.hasText(config)) {
 				return ConditionOutcome.match("Found logging.path: " + config);
 			}
+			config = new RelaxedPropertyResolver(environment, "endpoints.logfile.")
+					.getProperty("external-file");
+			if (StringUtils.hasText(config)) {
+				return ConditionOutcome
+						.match("Found endpoints.logfile.external-file: " + config);
+			}
 			return ConditionOutcome.noMatch("Found no log file configuration");
 		}
 

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/LogFileMvcEndpoint.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.actuate.endpoint.mvc;
 
+import java.io.File;
 import java.io.IOException;
 
 import javax.servlet.ServletException;
@@ -72,6 +73,12 @@ public class LogFileMvcEndpoint implements MvcEndpoint, EnvironmentAware {
 	 */
 	private Boolean sensitive;
 
+	/**
+	 * External Logfile to be accessed. Can be used if the logfile is written by output
+	 * redirect and not by the logging-system itself.
+	 */
+	private File externalFile;
+
 	private Environment environment;
 
 	@Override
@@ -105,6 +112,14 @@ public class LogFileMvcEndpoint implements MvcEndpoint, EnvironmentAware {
 		this.sensitive = sensitive;
 	}
 
+	public File getExternalFile() {
+		return this.externalFile;
+	}
+
+	public void setExternalFile(File externalFile) {
+		this.externalFile = externalFile;
+	}
+
 	@Override
 	@SuppressWarnings("rawtypes")
 	public Class<? extends Endpoint> getEndpointType() {
@@ -119,23 +134,25 @@ public class LogFileMvcEndpoint implements MvcEndpoint, EnvironmentAware {
 			return;
 		}
 		Resource resource = getLogFileResource();
+		if (resource != null && !resource.exists()) {
+			if (logger.isDebugEnabled()) {
+				logger.debug("Log file '" + resource + "' does not exist");
+			}
+			resource = null;
+		}
 		new Handler(resource).handleRequest(request, response);
 	}
 
 	private Resource getLogFileResource() {
+		if (this.externalFile != null) {
+			return new FileSystemResource(this.externalFile);
+		}
 		LogFile logFile = LogFile.get(this.environment);
 		if (logFile == null) {
 			logger.debug("Missing 'logging.file' or 'logging.path' properties");
 			return null;
 		}
-		FileSystemResource resource = new FileSystemResource(logFile.toString());
-		if (!resource.exists()) {
-			if (logger.isDebugEnabled()) {
-				logger.debug("Log file '" + resource + "' does not exist");
-			}
-			return null;
-		}
-		return resource;
+		return new FileSystemResource(logFile.toString());
 	}
 
 	/**

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/mvc/LogFileMvcEndpointTests.java

@@ -110,4 +110,15 @@ public class LogFileMvcEndpointTests {
 		assertThat(response.getContentAsString()).isEqualTo("--TEST--");
 	}
 
+	@Test
+	public void invokeGetsContentExternalFile() throws Exception {
+		this.mvc.setExternalFile(this.logFile);
+		MockHttpServletResponse response = new MockHttpServletResponse();
+		MockHttpServletRequest request = new MockHttpServletRequest(HttpMethod.GET.name(),
+				"/logfile");
+		this.mvc.invoke(request, response);
+		assertThat(response.getStatus()).isEqualTo(HttpStatus.OK.value());
+		assertThat("--TEST--").isEqualTo(response.getContentAsString());
+	}
+
 }