[KARAF-5772] Add balancing policy in HTTP proxy service

http/pom.xml

@@ -116,6 +116,7 @@
                             org.apache.karaf.http.command.completers,
                             org.apache.karaf.http.core.internal,
                             org.apache.karaf.http.core.internal.osgi,
+                            org.apache.karaf.http.core.internal.proxy,
                             org.apache.felix.utils.version,
                             org.apache.felix.utils.manifest;-split-package:=merge-first,
                             org.apache.http*,

http/src/main/java/org/apache/karaf/http/command/ProxyAddCommand.java

@@ -20,6 +20,7 @@
 import org.apache.karaf.shell.api.action.Action;
 import org.apache.karaf.shell.api.action.Argument;
 import org.apache.karaf.shell.api.action.Command;
+import org.apache.karaf.shell.api.action.Option;
 import org.apache.karaf.shell.api.action.lifecycle.Reference;
 import org.apache.karaf.shell.api.action.lifecycle.Service;
 
@@ -36,9 +37,12 @@ public class ProxyAddCommand implements Action {
     @Argument(index = 1, name = "proxyTo", description = "HTTP location to proxy on the prefix", required = true, multiValued = false)
     String proxyTo;
 
+    @Option(name = "-b", aliases = { "--lb" }, description = "Define the filter to the balancing service to use", required = false, multiValued = false)
+    String balancingPolicy;
+
     @Override
     public Object execute() throws Exception {
-        proxyService.addProxy(url, proxyTo);
+        proxyService.addProxy(url, proxyTo, balancingPolicy);
         return null;
     }
 

http/src/main/java/org/apache/karaf/http/command/ProxyBalancingListCommand.java

@@ -0,0 +1,40 @@
+/*
+ * 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.karaf.http.command;
+
+import org.apache.karaf.http.core.ProxyService;
+import org.apache.karaf.shell.api.action.Action;
+import org.apache.karaf.shell.api.action.Command;
+import org.apache.karaf.shell.api.action.lifecycle.Reference;
+import org.apache.karaf.shell.api.action.lifecycle.Service;
+
+@Command(scope = "http", name = "proxy-balancing-list", description = "List the available balancing policies")
+@Service
+public class ProxyBalancingListCommand implements Action {
+
+    @Reference
+    private ProxyService proxyService;
+
+    @Override
+    public Object execute() throws Exception {
+        for (String balancingPolicy : proxyService.getBalancingPolicies()) {
+            System.out.println(balancingPolicy);
+        }
+        return null;
+    }
+
+}

http/src/main/java/org/apache/karaf/http/command/ProxyListCommand.java

@@ -23,7 +23,7 @@
 import org.apache.karaf.shell.api.action.lifecycle.Service;
 import org.apache.karaf.shell.support.table.ShellTable;
 
-@Command(scope = "http", name = "proxies", description = "List the HTTP proxies")
+@Command(scope = "http", name = "proxy-list", description = "List the HTTP proxies")
 @Service
 public class ProxyListCommand implements Action {
 
@@ -35,8 +35,9 @@ public Object execute() throws Exception {
         ShellTable table = new ShellTable();
         table.column("URL");
         table.column("ProxyTo");
+        table.column("Balancing Policy");
         for (String url : proxyService.getProxies().keySet()) {
-             table.addRow().addContent(url, proxyService.getProxies().get(url));
+             table.addRow().addContent(url, proxyService.getProxies().get(url).getProxyTo(), proxyService.getProxies().get(url).getBalancingPolicy());
         }
         table.print(System.out);
         return null;

http/src/main/java/org/apache/karaf/http/core/BalancingPolicy.java

@@ -0,0 +1,29 @@
+/*
+ * 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.karaf.http.core;
+
+public interface BalancingPolicy {
+
+    /**
+     * Select a target proxy host in the given list.
+     *
+     * @param targets the list of hosts.
+     * @return the selected host in the list.
+     */
+    String selectHost(String[] targets);
+
+}

http/src/main/java/org/apache/karaf/http/core/HttpMBean.java

@@ -18,6 +18,7 @@
 
 import javax.management.MBeanException;
 import javax.management.openmbean.TabularData;
+import java.util.Collection;
 import java.util.Map;
 
 /**
@@ -36,12 +37,17 @@ public interface HttpMBean {
     /**
      * List configured HTTP proxies.
      */
-    Map<String, String> getProxies() throws MBeanException;
+    Map<String, Proxy> getProxies() throws MBeanException;
+
+    /**
+     * List the available balancing policies.
+     */
+    Collection<String> getProxyBalancingPolicies() throws MBeanException;
 
     /**
      * Add a new HTTP proxy using URL, proxyTo and prefix.
      */
-    void addProxy(String url, String proxyTo) throws MBeanException;
+    void addProxy(String url, String proxyTo, String balancingPolicy) throws MBeanException;
 
     /**
      * Remove an existing HTTP proxy identified by URL.

http/src/main/java/org/apache/karaf/http/core/Proxy.java

@@ -0,0 +1,58 @@
+/*
+ * 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.karaf.http.core;
+
+/**
+ * POJO describing proxy definition.
+ */
+public class Proxy {
+
+    private String url;
+    private String proxyTo;
+    private String balancingPolicy;
+
+    public Proxy(String url, String proxyTo, String balancingPolicy) {
+        this.url = url;
+        this.proxyTo = proxyTo;
+        this.balancingPolicy = balancingPolicy;
+    }
+
+    public String getUrl() {
+        return url;
+    }
+
+    public void setUrl(String url) {
+        this.url = url;
+    }
+
+    public String getProxyTo() {
+        return proxyTo;
+    }
+
+    public void setProxyTo(String proxyTo) {
+        this.proxyTo = proxyTo;
+    }
+
+    public String getBalancingPolicy() {
+        return balancingPolicy;
+    }
+
+    public void setBalancingPolicy(String balancingPolicy) {
+        this.balancingPolicy = balancingPolicy;
+    }
+
+}

http/src/main/java/org/apache/karaf/http/core/ProxyService.java

@@ -16,16 +16,20 @@
  */
 package org.apache.karaf.http.core;
 
+import java.util.Collection;
+import java.util.Dictionary;
 import java.util.Map;
 
 public interface ProxyService {
 
-    Map<String, String> getProxies();
+    Map<String, Proxy> getProxies();
 
-    void addProxy(String url, String proxyTo) throws Exception;
+    Collection<String> getBalancingPolicies() throws Exception;
+
+    void addProxy(String url, String proxyTo, String balancingProxy) throws Exception;
 
     void removeProxy(String url) throws Exception;
 
-    void initProxies();
+    void update(Dictionary<String, ?> properties);
 
 }

http/src/main/java/org/apache/karaf/http/core/internal/HttpMBeanImpl.java

@@ -17,6 +17,7 @@
 package org.apache.karaf.http.core.internal;
 
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -71,14 +72,23 @@ public TabularData getServlets() throws MBeanException {
     }
 
     @Override
-    public Map<String, String> getProxies() throws MBeanException {
+    public Map<String, Proxy> getProxies() throws MBeanException {
         return proxyService.getProxies();
     }
 
     @Override
-    public void addProxy(String url, String proxyTo) throws MBeanException {
+    public Collection<String> getProxyBalancingPolicies()  throws MBeanException {
         try {
-            proxyService.addProxy(url, proxyTo);
+            return proxyService.getBalancingPolicies();
+        } catch (Exception e) {
+            throw new MBeanException(null, e.toString());
+        }
+    }
+
+    @Override
+    public void addProxy(String url, String proxyTo, String balancingPolicy) throws MBeanException {
+        try {
+            proxyService.addProxy(url, proxyTo, balancingPolicy);
         } catch (Exception e) {
             throw new MBeanException(null, e.toString());
         }