Added heartbeat mechanism to detect and free up idle/closed sessions

src/main/java/eu/openanalytics/controllers/AppController.java

@@ -52,6 +52,8 @@ String app(ModelMap map, Principal principal, HttpServletRequest request) {
 		map.put("title", environment.getProperty("shiny.proxy.title"));
 		map.put("logo", environment.getProperty("shiny.proxy.logo-url"));
 		map.put("container", "/" + mapping + environment.getProperty("shiny.proxy.landing-page"));
+		map.put("heartbeatRate", environment.getProperty("shiny.proxy.heartbeat-rate", "10000"));
+
 		return "app";
 	}
 }

src/main/java/eu/openanalytics/controllers/HeartbeatController.java

@@ -0,0 +1,35 @@
+package eu.openanalytics.controllers;
+
+import java.io.IOException;
+import java.security.Principal;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.inject.Inject;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.RequestMapping;
+
+import eu.openanalytics.services.HeartbeatService;
+
+@Controller
+public class HeartbeatController {
+
+	@Inject
+	HeartbeatService heartbeatService;
+
+	@RequestMapping("/heartbeat/**")
+	void heartbeat(Principal principal, HttpServletRequest request, HttpServletResponse response) {
+		String userName = (principal == null) ? request.getSession().getId() : principal.getName();
+		Matcher matcher = Pattern.compile(".*/app/(.*)").matcher(request.getRequestURI());
+		String appName = matcher.matches() ? matcher.group(1) : null;
+		heartbeatService.heartbeatReceived(userName, appName);
+		try {
+			response.setStatus(200);
+			response.getWriter().write("Ok");
+			response.getWriter().flush();
+		} catch (IOException e) {}
+	}
+}

src/main/java/eu/openanalytics/services/DockerService.java

@@ -79,6 +79,7 @@ public static class Proxy {
 		public String containerId;
 		public String userName;
 		public String appName;
+		public long startupTimestamp;
 	}
 
 	@Bean
@@ -119,6 +120,7 @@ public List<Proxy> listProxies() {
 				copy.containerId = proxy.containerId;
 				copy.userName = proxy.userName;
 				copy.appName = proxy.appName;
+				copy.startupTimestamp = proxy.startupTimestamp;
 				proxies.add(copy);
 			}
 		}
@@ -218,6 +220,7 @@ private Proxy startProxy(String userName, String appName) {
 			ContainerInfo info = dockerClient.inspectContainer(container.id());
 			proxy.name = info.name().substring(1);
 			proxy.containerId = container.id();
+			proxy.startupTimestamp = System.currentTimeMillis();
 		} catch (Exception e) {
 			releasePort(proxy.port);
 			throw new ShinyProxyException("Failed to start container: " + e.getMessage(), e);

src/main/java/eu/openanalytics/services/HeartbeatService.java

@@ -0,0 +1,66 @@
+package eu.openanalytics.services;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import javax.annotation.PostConstruct;
+import javax.inject.Inject;
+
+import org.apache.log4j.Logger;
+import org.springframework.core.env.Environment;
+import org.springframework.stereotype.Service;
+
+import eu.openanalytics.services.DockerService.Proxy;
+
+@Service
+public class HeartbeatService {
+
+	@Inject
+	Environment environment;
+
+	@Inject
+	DockerService dockerService;
+
+	private Logger log = Logger.getLogger(HeartbeatService.class);
+
+	private Map<String, Long> heartbeatTimestamps;
+
+	@PostConstruct
+	public void init() {
+		heartbeatTimestamps = new ConcurrentHashMap<>();
+		new Thread(new AppCleaner(), "HeartbeatThread").start();
+	}
+
+	public void heartbeatReceived(String user, String app) {
+		heartbeatTimestamps.put(user, System.currentTimeMillis());
+	}
+
+	private class AppCleaner implements Runnable {
+		@Override
+		public void run() {
+			long cleanupInterval = 2 * Long.parseLong(environment.getProperty("shiny.proxy.heartbeat-rate", "10000"));
+			long heartbeatTimeout = Long.parseLong(environment.getProperty("shiny.proxy.heartbeat-timeout", "60000"));
+
+			while (true) {
+				try {
+					long currentTimestamp = System.currentTimeMillis();
+					for (Proxy proxy: dockerService.listProxies()) {
+						Long lastHeartbeat = heartbeatTimestamps.get(proxy.userName);
+						if (lastHeartbeat == null) lastHeartbeat = proxy.startupTimestamp;
+						long proxySilence = currentTimestamp - lastHeartbeat;
+						if (proxySilence > heartbeatTimeout) {
+							log.info(String.format("Releasing inactive proxy [user: %s] [app: %s] [silence: %dms]", proxy.userName, proxy.appName, proxySilence));
+							dockerService.releaseProxy(proxy.userName);
+							heartbeatTimestamps.remove(proxy.userName);
+						}
+					}
+				} catch (Throwable t) {
+					log.error("Error in HeartbeatThread", t);
+				}
+				try {
+					Thread.sleep(cleanupInterval);
+				} catch (InterruptedException e) {}
+			}
+		}
+	}
+}

src/main/resources/application.yml

@@ -3,6 +3,8 @@ shiny:
     title: Open Analytics Shiny Proxy
     logo-url: http://www.openanalytics.eu/sites/www.openanalytics.eu/themes/oa/logo.png
     landing-page: /
+    heartbeat-rate: 10000
+    heartbeat-timeout: 60000
     port: 8080
     authentication: ldap
     # LDAP configuration

src/main/resources/templates/app.html

@@ -17,8 +17,17 @@
 
 	<!-- content -->
     <iframe id="shinyframe" th:src="${container}" width="100%" style="margin-top: 50px; border: 0px;"></iframe>
-	<script type="text/javascript"> 
+	<script type="text/javascript" th:inline="javascript"> 
 		$('#shinyframe').css('height', ($(window).height()-50)+'px');
+
+		function heartbeat() {
+		    setTimeout(function() {
+		        $.ajax("/heartbeat" + window.location.pathname).success(function(data) {
+		        	heartbeat();
+		        });
+		    }, [[${heartbeatRate}]]);
+		};
+		heartbeat();
 	</script>
 </body>
 </html>