Upgrade to Tomcat 8.0.28 and test support for SSL config from classpath

Prior to 8.0.28 Tomcat required the key store and trust store (if any)
to be available directly on the filesystem, i.e. classpath: resources
would not work. Tomcat 8.0.28 removed this limitation.

This commit updates to Tomcat 8.0.28, updates the tests to verify
the new Tomcat capability and removes the obsolete documentation of
the restriction.

Closes gh-4048

spring-boot-dependencies/pom.xml

@@ -134,7 +134,7 @@
 		<thymeleaf-extras-conditionalcomments.version>2.1.1.RELEASE</thymeleaf-extras-conditionalcomments.version>
 		<thymeleaf-layout-dialect.version>1.2.9</thymeleaf-layout-dialect.version>
 		<thymeleaf-extras-data-attribute.version>1.3</thymeleaf-extras-data-attribute.version>
-		<tomcat.version>8.0.26</tomcat.version>
+		<tomcat.version>8.0.28</tomcat.version>
 		<undertow.version>1.1.8.Final</undertow.version>
 		<velocity.version>1.7</velocity.version>
 		<velocity-tools.version>2.0</velocity-tools.version>

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

@@ -423,10 +423,6 @@ typically in `application.properties` or `application.yml`. For example:
 See {sc-spring-boot}/context/embedded/Ssl.{sc-ext}[`Ssl`] for details of all of the
 supported properties.
 
-NOTE: Tomcat requires the key store (and trust store if you're using one) to be directly
-accessible on the filesystem, i.e. it cannot be read from within a jar file. This
-limitation doesn't apply to Jetty and Undertow.
-
 Using configuration like the example above means the application will no longer support
 plain HTTP connector at port 8080. Spring Boot doesn't support the configuration of both
 an HTTP connector and an HTTPS connector via `application.properties`. If you want to

spring-boot-samples/spring-boot-sample-tomcat-ssl/src/main/resources/application.properties

 server.port = 8443
-server.ssl.key-store = sample.jks
+server.ssl.key-store = classpath:sample.jks
 server.ssl.key-store-password = secret
-server.ssl.key-password = password
+server.ssl.key-password = password
\ No newline at end of file

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

@@ -285,8 +285,7 @@ public class TomcatEmbeddedServletContainerFactory
 
 	private void configureSslKeyStore(AbstractHttp11JsseProtocol<?> protocol, Ssl ssl) {
 		try {
-			File file = ResourceUtils.getFile(ssl.getKeyStore());
-			protocol.setKeystoreFile(file.getAbsolutePath());
+			protocol.setKeystoreFile(ResourceUtils.getURL(ssl.getKeyStore()).toString());
 		}
 		catch (FileNotFoundException ex) {
 			throw new EmbeddedServletContainerException(
@@ -303,8 +302,8 @@ public class TomcatEmbeddedServletContainerFactory
 	private void configureSslTrustStore(AbstractHttp11JsseProtocol<?> protocol, Ssl ssl) {
 		if (ssl.getTrustStore() != null) {
 			try {
-				File file = ResourceUtils.getFile(ssl.getTrustStore());
-				protocol.setTruststoreFile(file.getAbsolutePath());
+				protocol.setTruststoreFile(
+						ResourceUtils.getURL(ssl.getTrustStore()).toString());
 			}
 			catch (FileNotFoundException ex) {
 				throw new EmbeddedServletContainerException(

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

@@ -311,14 +311,19 @@ public abstract class AbstractEmbeddedServletContainerFactoryTests {
 	}
 
 	@Test
-	public void basicSsl() throws Exception {
+	public void basicSslFromClassPath() throws Exception {
+		testBasicSslWithKeyStore("classpath:test.jks");
+	}
+
+	@Test
+	public void basicSslFromFileSystem() throws Exception {
 		testBasicSslWithKeyStore("src/test/resources/test.jks");
 	}
 
 	@Test
 	public void sslDisabled() throws Exception {
 		AbstractEmbeddedServletContainerFactory factory = getFactory();
-		Ssl ssl = getSsl(null, "password", "src/test/resources/test.jks");
+		Ssl ssl = getSsl(null, "password", "classpath:test.jks");
 		ssl.setEnabled(false);
 		factory.setSsl(ssl);
 		this.container = factory.getEmbeddedServletContainer(
@@ -374,8 +379,8 @@ public abstract class AbstractEmbeddedServletContainerFactoryTests {
 	public void pkcs12KeyStoreAndTrustStore() throws Exception {
 		AbstractEmbeddedServletContainerFactory factory = getFactory();
 		addTestTxtFile(factory);
-		factory.setSsl(getSsl(ClientAuth.NEED, null, "src/test/resources/test.p12",
-				"src/test/resources/test.p12"));
+		factory.setSsl(getSsl(ClientAuth.NEED, null, "classpath:test.p12",
+				"classpath:test.p12"));
 		this.container = factory.getEmbeddedServletContainer();
 		this.container.start();
 		KeyStore keyStore = KeyStore.getInstance("pkcs12");
@@ -398,8 +403,8 @@ public abstract class AbstractEmbeddedServletContainerFactoryTests {
 			throws Exception {
 		AbstractEmbeddedServletContainerFactory factory = getFactory();
 		addTestTxtFile(factory);
-		factory.setSsl(getSsl(ClientAuth.NEED, "password", "src/test/resources/test.jks",
-				"src/test/resources/test.jks"));
+		factory.setSsl(getSsl(ClientAuth.NEED, "password", "classpath:test.jks",
+				"classpath:test.jks"));
 		this.container = factory.getEmbeddedServletContainer();
 		this.container.start();
 		KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
@@ -422,8 +427,7 @@ public abstract class AbstractEmbeddedServletContainerFactoryTests {
 			throws Exception {
 		AbstractEmbeddedServletContainerFactory factory = getFactory();
 		addTestTxtFile(factory);
-		factory.setSsl(
-				getSsl(ClientAuth.NEED, "password", "src/test/resources/test.jks"));
+		factory.setSsl(getSsl(ClientAuth.NEED, "password", "classpath:test.jks"));
 		this.container = factory.getEmbeddedServletContainer();
 		this.container.start();
 		SSLConnectionSocketFactory socketFactory = new SSLConnectionSocketFactory(
@@ -441,8 +445,7 @@ public abstract class AbstractEmbeddedServletContainerFactoryTests {
 			throws Exception {
 		AbstractEmbeddedServletContainerFactory factory = getFactory();
 		addTestTxtFile(factory);
-		factory.setSsl(
-				getSsl(ClientAuth.WANT, "password", "src/test/resources/test.jks"));
+		factory.setSsl(getSsl(ClientAuth.WANT, "password", "classpath:test.jks"));
 		this.container = factory.getEmbeddedServletContainer();
 		this.container.start();
 		KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
@@ -465,8 +468,7 @@ public abstract class AbstractEmbeddedServletContainerFactoryTests {
 			throws Exception {
 		AbstractEmbeddedServletContainerFactory factory = getFactory();
 		addTestTxtFile(factory);
-		factory.setSsl(
-				getSsl(ClientAuth.WANT, "password", "src/test/resources/test.jks"));
+		factory.setSsl(getSsl(ClientAuth.WANT, "password", "classpath:test.jks"));
 		this.container = factory.getEmbeddedServletContainer();
 		this.container.start();
 		SSLConnectionSocketFactory socketFactory = new SSLConnectionSocketFactory(