Configure Tomcat to create upload targets

Previously, if the directory to which Tomcat would write a file upload did not exist
the upload attempt would fail and a 500 response would be returned to the client.
This could happen when, for example, Tomcat is using a temporary directory for file
uploads and tmpwatch has deleted the directory.

This commit configures Tomcat so that, during multipart request parsing, it will
automatically create the directory to which the parts will be written if it does not
already exist.

Closes gh-9616

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -2306,13 +2306,6 @@ Spring Boot includes support for embedded Tomcat, Jetty, and Undertow servers. M
 developers will simply use the appropriate '`Starter`' to obtain a fully configured
 instance. By default the embedded server will listen for HTTP requests on port `8080`.
 
-WARNING: If you choose to use Tomcat on CentOS be aware that, by default, a temporary
-directory is used to store compiled JSPs, file uploads etc. This directory may be
-deleted by `tmpwatch` while your application is running leading to failures. To avoid
-this, you may want to customize your `tmpwatch` configuration so that `tomcat.*`
-directories are not deleted, or configure `server.tomcat.basedir` so that embedded Tomcat
-uses a different location.
-
 
 
 [[boot-features-embedded-container-servlets-filters-listeners]]

spring-boot/src/main/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainerFactory.java

@@ -206,6 +206,12 @@ protected void prepareContext(Host host, ServletContextInitializer[] initializer
 		catch (NoSuchMethodError ex) {
 			// Tomcat is < 8.0.30. Continue
 		}
+		try {
+			context.setCreateUploadTargets(true);
+		}
+		catch (NoSuchMethodError ex) {
+			// Tomcat is < 8.5.39. Continue.
+		}
 		SkipPatternJarScanner.apply(context, this.tldSkipPatterns);
 		WebappLoader loader = new WebappLoader(context.getParentClassLoader());
 		loader.setLoaderClass(TomcatEmbeddedWebappClassLoader.class.getName());

spring-boot/src/test/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainerFactoryTests.java

@@ -18,6 +18,7 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.net.URISyntaxException;
 import java.nio.charset.Charset;
 import java.util.Arrays;
 import java.util.Locale;
@@ -30,10 +31,15 @@
 import javax.servlet.Filter;
 import javax.servlet.FilterChain;
 import javax.servlet.FilterConfig;
+import javax.servlet.MultipartConfigElement;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
+import javax.servlet.ServletRegistration.Dynamic;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 
 import org.apache.catalina.Container;
 import org.apache.catalina.Context;
@@ -63,8 +69,18 @@
 import org.springframework.boot.context.embedded.Ssl;
 import org.springframework.boot.testutil.InternalOutputCapture;
 import org.springframework.boot.web.servlet.ServletContextInitializer;
+import org.springframework.core.io.ByteArrayResource;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
 import org.springframework.test.util.ReflectionTestUtils;
+import org.springframework.util.FileSystemUtils;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
 import org.springframework.util.SocketUtils;
+import org.springframework.web.client.RestTemplate;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.Assert.fail;
@@ -539,6 +555,49 @@ public void destroy() {
 		}
 	}
 
+	@Test
+	public void nonExistentUploadDirectoryIsCreatedUponMultipartUpload()
+			throws IOException, URISyntaxException {
+		TomcatEmbeddedServletContainerFactory factory = new TomcatEmbeddedServletContainerFactory(
+				0);
+		AtomicReference<ServletContext> servletContextReference = new AtomicReference<>();
+		factory.addInitializers(new ServletContextInitializer() {
+
+			@Override
+			public void onStartup(ServletContext servletContext) throws ServletException {
+				servletContextReference.set(servletContext);
+				Dynamic servlet = servletContext.addServlet("upload", new HttpServlet() {
+
+					@Override
+					protected void doPost(HttpServletRequest req,
+							HttpServletResponse resp)
+							throws ServletException, IOException {
+						req.getParts();
+					}
+
+				});
+				servlet.addMapping("/upload");
+				servlet.setMultipartConfig(new MultipartConfigElement((String) null));
+			}
+
+		});
+		this.container = factory.getEmbeddedServletContainer();
+		this.container.start();
+		File temp = (File) servletContextReference.get()
+				.getAttribute(ServletContext.TEMPDIR);
+		FileSystemUtils.deleteRecursively(temp);
+		RestTemplate restTemplate = new RestTemplate();
+		HttpHeaders headers = new HttpHeaders();
+		MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
+		body.add("file", new ByteArrayResource(new byte[1024 * 1024]));
+		headers.setContentType(MediaType.MULTIPART_FORM_DATA);
+		HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(body,
+				headers);
+		ResponseEntity<String> response = restTemplate
+				.postForEntity(getLocalUrl("/upload"), requestEntity, String.class);
+		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+	}
+
 	@Override
 	protected JspServlet getJspServlet() throws ServletException {
 		Container context = ((TomcatEmbeddedServletContainer) this.container).getTomcat()