Added basic migration capability to org.apache.brooklyn.entity.webapp.*

This effector is pluggable via brooklyn.initializers,

Example YAML:

```
name: My Migrable WebApp
location: aws-ireland
services:
- type: org.apache.brooklyn.entity.webapp.tomcat.TomcatServer
  name: AppServer HelloWorld
  brooklyn.config:
    wars.root: http://search.maven.org/remotecontent?filepath=io/brooklyn/example/brooklyn-example-hello-world-sql-webapp/0.6.0/brooklyn-example-hello-world-sql-webapp-0.6.0.war
  brooklyn.initializers:
  - type: org.apache.brooklyn.entity.webapp.JavaWebAppMigrateEffector
```

core/src/main/java/org/apache/brooklyn/core/effector/MigrateEffector.java

@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.brooklyn.core.effector;
+
+import com.google.common.annotations.Beta;
+import org.apache.brooklyn.core.annotation.Effector;
+import org.apache.brooklyn.core.annotation.EffectorParam;
+
+@Beta
+public interface MigrateEffector {
+
+    MethodEffector<Void> MIGRATE = new MethodEffector<Void>(MigrateEffector.class, "migrate");
+    String MIGRATE_LOCATION_SPEC = "locationSpec";
+
+    /**
+     * Starts a migration process.
+     * It calls stop() on the original locations and start() on the new one.
+     * <p/>
+     * After this process finishes it refreshes all the sibling entities dependent data (ConfigKeys, Env variables...)
+     */
+    @Beta
+    @Effector(description = "Migrates the current entity to another location. It will free the provisioned resources" +
+            " used by the former location")
+    void migrate(@EffectorParam(name = MIGRATE_LOCATION_SPEC, description = "Location Spec", nullable = false) String locationSpec);
+}

core/src/main/java/org/apache/brooklyn/core/initializer/AddMigrateEffectorEntityInitializer.java

@@ -0,0 +1,118 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.brooklyn.core.initializer;
+
+import com.google.common.annotations.Beta;
+import com.google.common.collect.Lists;
+import org.apache.brooklyn.api.entity.Entity;
+import org.apache.brooklyn.api.entity.EntityInitializer;
+import org.apache.brooklyn.api.entity.EntityLocal;
+import org.apache.brooklyn.api.location.Location;
+import org.apache.brooklyn.core.effector.MigrateEffector;
+import org.apache.brooklyn.core.effector.EffectorBody;
+import org.apache.brooklyn.core.entity.Attributes;
+import org.apache.brooklyn.core.entity.Entities;
+import org.apache.brooklyn.core.entity.EntityInternal;
+import org.apache.brooklyn.core.entity.lifecycle.Lifecycle;
+import org.apache.brooklyn.core.entity.lifecycle.ServiceStateLogic;
+import org.apache.brooklyn.core.entity.trait.Startable;
+import org.apache.brooklyn.util.collections.MutableMap;
+import org.apache.brooklyn.util.core.config.ConfigBag;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@Beta
+public class AddMigrateEffectorEntityInitializer implements EntityInitializer {
+
+    private static final Logger LOG = LoggerFactory.getLogger(AddMigrateEffectorEntityInitializer.class);
+
+    @Override
+    public void apply(final EntityLocal entity) {
+        if (LOG.isDebugEnabled()) {
+            LOG.debug("Adding Migrate effector to {}", entity);
+        }
+
+        ((EntityInternal) entity).getMutableEntityType().addEffector(MigrateEffector.MIGRATE, new EffectorBody<Void>() {
+            @Override
+            public Void call(ConfigBag parameters) {
+                migrate((EntityInternal) entity, (String) parameters.getStringKey(MigrateEffector.MIGRATE_LOCATION_SPEC));
+                return null;
+            }
+        });
+    }
+
+    private static void migrate(EntityInternal entity, String locationSpec) {
+        if (entity.sensors().get(Attributes.SERVICE_STATE_ACTUAL) != Lifecycle.RUNNING) {
+            // Is it necessary to check if the whole application is healthy?
+            throw new RuntimeException("The entity needs to be healthy before the migration starts");
+        }
+
+        if (entity.getParent() != null && !entity.getParent().equals(entity.getApplication())) {
+            /*
+             * TODO: Allow nested entites to be migrated
+             * If the entity has a parent different to the application root the migration cannot be done right now,
+             * as it could lead into problems to deal with hierarchies like SameServerEntity -> Entity
+             */
+
+            throw new RuntimeException("Nested entities cannot be migrated right now");
+        }
+
+        // Retrieving the location from the catalog.
+        Location newLocation = Entities.getManagementContext(entity).getLocationRegistry().resolve(locationSpec);
+
+        // TODO: Find a better way to check if you're migrating an entity to the exactly same VM. This not always works.
+        for (Location oldLocation : entity.getLocations()) {
+            if (oldLocation.containsLocation(newLocation)) {
+                LOG.warn("You cannot migrate an entity to the same location, the migration process will stop right now");
+                return;
+            }
+        }
+
+        LOG.info("Migration process of " + entity.getId() + " started.");
+
+        // When we have the new location, we free the resources of the current instance
+        entity.invoke(Startable.STOP, MutableMap.<String, Object>of()).blockUntilEnded();
+
+        // Clearing old locations to remove the relationship with the previous instance
+        entity.clearLocations();
+        entity.addLocations(Lists.newArrayList(newLocation));
+
+        // Starting the new instance
+        entity.invoke(Startable.START, MutableMap.<String, Object>of()).blockUntilEnded();
+
+        // Refresh all the dependent entities
+
+        for (Entity applicationChild : entity.getApplication().getChildren()) {
+            // TODO: Find a better way to refresh the application configuration.
+            // TODO: Refresh nested entities or find a way to propagate the restart properly.
+
+            // Restart any entity but the migrated one.
+            if (applicationChild instanceof Startable) {
+                if (entity.equals(applicationChild)) {
+                    // The entity is sensors should rewired automatically on stop() + restart()
+                } else {
+                    // Restart the entity to fetch again all the dependencies (ie. attributeWhenReady ones)
+                    ((Startable) applicationChild).restart();
+                }
+            }
+        }
+
+        LOG.info("Migration process of " + entity.getId() + " finished.");
+    }
+}

software/webapp/src/main/java/org/apache/brooklyn/entity/webapp/JavaWebAppSshDriver.java

@@ -18,23 +18,24 @@
  */
 package org.apache.brooklyn.entity.webapp;
 
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import java.io.File;
-import java.net.URI;
-import java.util.Set;
-
+import com.google.common.collect.ImmutableList;
 import com.google.common.net.HostAndPort;
 import org.apache.brooklyn.core.entity.Attributes;
 import org.apache.brooklyn.core.location.access.BrooklynAccessUtils;
 import org.apache.brooklyn.entity.java.JavaSoftwareProcessSshDriver;
+import org.apache.brooklyn.entity.java.UsesJmx;
+import org.apache.brooklyn.feed.jmx.JmxHelper;
 import org.apache.brooklyn.location.ssh.SshMachineLocation;
 import org.apache.brooklyn.util.core.task.DynamicTasks;
 import org.apache.brooklyn.util.core.task.Tasks;
 import org.apache.brooklyn.util.core.task.ssh.SshTasks;
 import org.apache.brooklyn.util.text.Strings;
 
-import com.google.common.collect.ImmutableList;
+import java.io.File;
+import java.net.URI;
+import java.util.Set;
+
+import static com.google.common.base.Preconditions.checkNotNull;
 
 public abstract class JavaWebAppSshDriver extends JavaSoftwareProcessSshDriver implements JavaWebAppDriver {
 
@@ -112,6 +113,10 @@ public void postLaunch() {
         String rootUrl = inferRootUrl();
         entity.sensors().set(Attributes.MAIN_URI, URI.create(rootUrl));
         entity.sensors().set(WebAppService.ROOT_URL, rootUrl);
+
+        // JMX_SERVICE_URL is not updated properly when the locations changes so we update in postlaunch to avoid
+        // isRunning to fail finding the right location to check.
+        entity.sensors().set(UsesJmx.JMX_URL, JmxHelper.toJmxmpUrl(getHostname(), entity.getAttribute(UsesJmx.JMX_PORT)));
     }
 
     /** 

software/webapp/src/test/java/org/apache/brooklyn/entity/webapp/WebAppMigrationLiveTest.java

@@ -0,0 +1,141 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.brooklyn.entity.webapp;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.brooklyn.api.entity.EntitySpec;
+import org.apache.brooklyn.api.location.ProvisioningLocation;
+import org.apache.brooklyn.core.effector.Effectors;
+import org.apache.brooklyn.core.entity.Attributes;
+import org.apache.brooklyn.core.initializer.AddMigrateEffectorEntityInitializer;
+import org.apache.brooklyn.core.internal.BrooklynProperties;
+import org.apache.brooklyn.core.test.BrooklynAppLiveTestSupport;
+import org.apache.brooklyn.core.test.entity.LocalManagementContextForTests;
+import org.apache.brooklyn.core.effector.MigrateEffector;
+import org.apache.brooklyn.entity.webapp.jboss.JBoss6Server;
+import org.apache.brooklyn.entity.webapp.jboss.JBoss7Server;
+import org.apache.brooklyn.entity.webapp.jetty.Jetty6Server;
+import org.apache.brooklyn.entity.webapp.tomcat.Tomcat8Server;
+import org.apache.brooklyn.entity.webapp.tomcat.TomcatServer;
+import org.apache.brooklyn.test.EntityTestUtils;
+import org.apache.brooklyn.test.HttpTestUtils;
+import org.apache.brooklyn.test.support.TestResourceUnavailableException;
+import org.apache.brooklyn.util.collections.MutableMap;
+import org.apache.brooklyn.util.time.Duration;
+import org.reflections.Reflections;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+// This test could extend AbstractEc2LiveTest but then it will not be able to be parametrized properly.
+public class WebAppMigrationLiveTest extends BrooklynAppLiveTestSupport {
+    private static final String PROVIDER = "aws-ec2";
+    private static final String REGION_NAME = "us-west-2";
+    private static final String LOCATION_SPEC = PROVIDER + (REGION_NAME == null ? "" : ":" + REGION_NAME);
+
+    private BrooklynProperties brooklynProperties;
+    private ProvisioningLocation amazonProvisioningLocation;
+
+    @Override
+    @BeforeMethod(alwaysRun = true)
+    public void setUp() throws Exception {
+        brooklynProperties = BrooklynProperties.Factory.newDefault();
+
+        // EC2 setup obtained from AbstractEc2LiveTest
+        brooklynProperties.remove("brooklyn.jclouds." + PROVIDER + ".image-description-regex");
+        brooklynProperties.remove("brooklyn.jclouds." + PROVIDER + ".image-name-regex");
+        brooklynProperties.remove("brooklyn.jclouds." + PROVIDER + ".image-id");
+        brooklynProperties.remove("brooklyn.jclouds." + PROVIDER + ".inboundPorts");
+        brooklynProperties.remove("brooklyn.jclouds." + PROVIDER + ".hardware-id");
+
+        // Also removes scriptHeader (e.g. if doing `. ~/.bashrc` and `. ~/.profile`, then that can cause "stdin: is not a tty")
+        brooklynProperties.remove("brooklyn.ssh.config.scriptHeader");
+        mgmt = new LocalManagementContextForTests(brooklynProperties);
+        amazonProvisioningLocation = (ProvisioningLocation) mgmt.getLocationRegistry().resolve(LOCATION_SPEC);
+        super.setUp();
+    }
+
+    @DataProvider(name = "webAppEntities")
+    public Object[][] webAppEntities() {
+        Object[][] dataProviderResult = new Object[][] {
+                {EntitySpec.create(JBoss6Server.class)},
+                {EntitySpec.create(JBoss7Server.class)},
+                {EntitySpec.create(Jetty6Server.class)},
+                {EntitySpec.create(TomcatServer.class)},
+                {EntitySpec.create(Tomcat8Server.class)}
+        };
+
+       return dataProviderResult;
+    }
+
+
+    private List<Object[]> getEntitiesFromClasses(Set<Class<? extends JavaWebAppSoftwareProcess>> clazzSet) {
+        ArrayList<Object[]> entitiyList = new ArrayList<>();
+
+        for (Class clazz : clazzSet) {
+            if (clazz.isInterface() && !clazz.getName().contains("JavaWebAppSoftwareProcess")) {
+                EntitySpec entity = EntitySpec.create(clazz);
+                entitiyList.add(new Object[]{entity});
+            }
+
+        }
+
+
+        return entitiyList;
+    }
+
+    private String getTestWar() {
+        TestResourceUnavailableException.throwIfResourceUnavailable(getClass(), "/hello-world.war");
+        return "classpath://hello-world.war";
+    }
+
+    @Test(groups = "Live", dataProvider = "webAppEntities")
+    public void testMigration(EntitySpec<? extends JavaWebAppSoftwareProcess> webServerSpec) throws Exception {
+        final JavaWebAppSoftwareProcess server = app.createAndManageChild(webServerSpec
+                .addInitializer(new AddMigrateEffectorEntityInitializer())
+                .configure(JavaWebAppSoftwareProcess.OPEN_IPTABLES, true)
+                .configure("war", getTestWar()));
+
+        // Run the webserver in the premigration location
+        app.start(ImmutableList.of(amazonProvisioningLocation));
+        EntityTestUtils.assertAttributeEqualsEventually(server, Attributes.SERVICE_UP, Boolean.TRUE);
+
+        // Check if the WebServer is reachable in the premigration location
+        String preMigrationUrl = server.getAttribute(JavaWebAppSoftwareProcess.ROOT_URL);
+        HttpTestUtils.assertUrlReachable(preMigrationUrl);
+
+        // Start the migration process
+        Effectors.invocation(MigrateEffector.MIGRATE, MutableMap.of("locationSpec", LOCATION_SPEC), server).asTask().blockUntilEnded(Duration.FIVE_MINUTES);
+        EntityTestUtils.assertAttributeEqualsEventually(server, Attributes.SERVICE_UP, Boolean.TRUE);
+
+        // Check if the WebServer is reachable in the postmigration location
+        String afterMigrationUrl = server.getAttribute(JavaWebAppSoftwareProcess.ROOT_URL);
+        HttpTestUtils.assertUrlReachable(afterMigrationUrl);
+
+        // Check if the old location was unprovisioned succesfully
+        HttpTestUtils.assertUrlUnreachable(preMigrationUrl);
+
+    }
+
+
+}