Add support for using RemoteSpringApplication behind a proxy

This commit adds two new properties, spring.devtools.remote.proxy.host
and spring.devtools.remote.proxy.port that can be used to configure
RemoteSpringApplication to connect to the remote application through
an HTTP proxy.

Closes gh-3968

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/RemoteDevToolsProperties.java

@@ -50,6 +50,8 @@ public class RemoteDevToolsProperties {
 
 	private Debug debug = new Debug();
 
+	private Proxy proxy = new Proxy();
+
 	public String getContextPath() {
 		return this.contextPath;
 	}
@@ -82,6 +84,10 @@ public class RemoteDevToolsProperties {
 		return this.debug;
 	}
 
+	public Proxy getProxy() {
+		return this.proxy;
+	}
+
 	public static class Restart {
 
 		/**
@@ -131,4 +137,34 @@ public class RemoteDevToolsProperties {
 
 	}
 
+	public static class Proxy {
+
+		/**
+		 * The host of the proxy to use to connect to the remote application.
+		 */
+		private String host;
+
+		/**
+		 * The port of the proxy to use to connect to the remote application.
+		 */
+		private Integer port;
+
+		public String getHost() {
+			return this.host;
+		}
+
+		public void setHost(String host) {
+			this.host = host;
+		}
+
+		public Integer getPort() {
+			return this.port;
+		}
+
+		public void setPort(Integer port) {
+			this.port = port;
+		}
+
+	}
+
 }

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/remote/client/RemoteClientConfiguration.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.devtools.remote.client;
 
+import java.net.InetSocketAddress;
+import java.net.Proxy.Type;
 import java.net.URL;
 import java.util.Arrays;
 import java.util.List;
@@ -37,6 +39,7 @@ import org.springframework.boot.devtools.autoconfigure.DevToolsProperties;
 import org.springframework.boot.devtools.autoconfigure.DevToolsProperties.Restart;
 import org.springframework.boot.devtools.autoconfigure.OptionalLiveReloadServer;
 import org.springframework.boot.devtools.autoconfigure.RemoteDevToolsProperties;
+import org.springframework.boot.devtools.autoconfigure.RemoteDevToolsProperties.Proxy;
 import org.springframework.boot.devtools.autoconfigure.TriggerFileFilter;
 import org.springframework.boot.devtools.classpath.ClassPathChangedEvent;
 import org.springframework.boot.devtools.classpath.ClassPathFileSystemWatcher;
@@ -91,8 +94,13 @@ public class RemoteClientConfiguration {
 	public ClientHttpRequestFactory clientHttpRequestFactory() {
 		List<ClientHttpRequestInterceptor> interceptors = Arrays
 				.asList(getSecurityInterceptor());
-		return new InterceptingClientHttpRequestFactory(
-				new SimpleClientHttpRequestFactory(), interceptors);
+		SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
+		Proxy proxy = this.properties.getRemote().getProxy();
+		if (proxy.getHost() != null && proxy.getPort() != null) {
+			requestFactory.setProxy(new java.net.Proxy(Type.HTTP, new InetSocketAddress(
+					proxy.getHost(), proxy.getPort())));
+		}
+		return new InterceptingClientHttpRequestFactory(requestFactory, interceptors);
 	}
 
 	private ClientHttpRequestInterceptor getSecurityInterceptor() {

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

@@ -674,6 +674,8 @@ content into your application; rather pick only the properties that you need.
     spring.devtools.remote.context-path=/.~~spring-boot!~ # context path used to handle the remote connection
     spring.devtools.remote.debug.enabled=true # enable remote debug support
     spring.devtools.remote.debug.local-port=8000 # local remote debug server port
+    spring.devtools.remote.proxy.host= # the host of the proxy to use to connect to the remote application
+    spring.devtools.remote.proxy.port= # the port of the proxy to use to connect to the remote application
     spring.devtools.remote.restart.enabled=true # enable remote restart
     spring.devtools.remote.secret= # a shared secret required to establish a connection
     spring.devtools.remote.secret-header-name=X-AUTH-TOKEN # HTTP header used to transfer the shared secret

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

@@ -1064,6 +1064,9 @@ property is read and passed to the server for authentication.
 TIP: It's always advisable to use `https://` as the connection protocol so that traffic is
 encrypted and passwords cannot be intercepted.
 
+TIP: If you need to use a proxy to access the remote application, configure the
+`spring.devtools.remote.proxy.host` and `spring.devtools.remote.proxy.port` properties.
+
 
 
 [[using-boot-devtools-remote-update]]