XDOCKER-51: Expose configuration options to configure an XWiki cluster

README.md

@@ -361,6 +361,76 @@ secrets:
       name: xwiki-db-root-password
 ```
 
+## Configuring clustering
+
+Read about [setting communication channels](https://www.xwiki.org/xwiki/bin/view/Documentation/AdminGuide/Clustering/).
+
+#### Docker Compose example
+
+```yaml
+version: '2'
+networks:
+  bridge:
+    driver: bridge
+services:
+  web:
+    build: .
+    container_name: xwiki-postgres-tomcat-web
+    depends_on:
+      - db
+    ports:
+      - "8080:8080"
+    environment:
+      - XWIKI_VERSION=${XWIKI_VERSION}
+      - DB_USER=${DB_USER}
+      - DB_PASSWORD=${DB_PASSWORD}
+      - DB_DATABASE=${DB_DATABASE}
+      - DB_HOST=xwiki-postgres-db
+      - CLUSTER=true
+      - CLUSTER_CHANNEL=udp
+    volumes:
+      - xwiki-data-b:/usr/local/xwiki
+    networks:
+      - bridge
+  web2:
+    build: .
+    container_name: xwiki-postgres-tomcat-web2
+    depends_on:
+      - db
+    ports:
+      - "8081:8080"
+    environment:
+      - XWIKI_VERSION=${XWIKI_VERSION}
+      - DB_USER=${DB_USER}
+      - DB_PASSWORD=${DB_PASSWORD}
+      - DB_DATABASE=${DB_DATABASE}
+      - DB_HOST=xwiki-postgres-db
+      - CLUSTER=true
+      - CLUSTER_CHANNEL=udp
+    volumes:
+      - xwiki-data-b:/usr/local/xwiki
+    networks:
+      - bridge
+  db:
+    image: "postgres:9.5-alpine"
+    container_name: xwiki-postgres-db
+    volumes:
+      - postgres-data-b:/var/lib/postgresql/data
+    environment:
+      - POSTGRES_ROOT_PASSWORD=${POSTGRES_ROOT_PASSWORD}
+      - POSTGRES_PASSWORD=${DB_PASSWORD}
+      - POSTGRES_USER=${DB_USER}
+      - POSTGRES_DB=${DB_DATABASE}
+      - POSTGRES_INITDB_ARGS="--encoding=UTF8"
+    networks:
+      - bridge
+volumes:
+  postgres-data-b: {}
+  xwiki-data-b: {}
+
+```
+
+
 ## Using an external Solr service
 
 From the [XWiki Solr Search API documentation](https://extensions.xwiki.org/xwiki/bin/view/Extension/Solr%20Search%20API):
@@ -516,6 +586,8 @@ The first time you create a container out of the xwiki image, a shell script (`/
 -	`DB_HOST`: The name of the host (or docker container) containing the database. Default is "db".
 -	`INDEX_HOST`: The hostname of an externally configured Solr instance. Defaults to "localhost", and configures an embedded Solr instance.
 -	`INDEX_PORT`: The port used by an externally configured Solr instance. Defaults to 8983.
+- `CLUSTER`: Set it to "true" to enable clustering.
+- `CLUSTER_CHANNEL`: The JGroups channel name.
 
 In order to support [Docker secrets](https://docs.docker.com/engine/swarm/secrets/), these configuration values can also be given to the container as files containing that value.
 

build.gradle

@@ -79,6 +79,13 @@ task generate() {
                     expand(tokens[version])
                     filteringCharset = 'UTF-8'
                 }
+                // Copy JGroups files
+                copy {
+                    from 'template'
+                    into "${version}/${variant}"
+                    include "jgroups/*"
+                    filteringCharset = 'UTF-8'
+                }
             }
         }
     }

template/Dockerfile

@@ -72,6 +72,9 @@ COPY tomcat/setenv.sh /usr/local/tomcat/bin/
 # Setup the XWiki Hibernate configuration
 COPY xwiki/hibernate.cfg.xml /usr/local/tomcat/webapps/ROOT/WEB-INF/hibernate.cfg.xml
 
+# Configure JGroups. 
+COPY jgroups/* /usr/local/tomcat/webapps/ROOT/WEB-INF/observation/remote/jgroups
+
 # Set a specific distribution id in XWiki for this docker packaging.
 RUN sed -i \'s/<id>org.xwiki.platform:xwiki-platform-distribution-war/<id>org.xwiki.platform:xwiki-platform-distribution-docker/\' \\
   /usr/local/tomcat/webapps/ROOT/META-INF/extension.xed

template/jgroups/udp.xml

@@ -0,0 +1,101 @@
+<!--
+ * See the NOTICE file distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+-->
+
+<!--
+  Default stack using IP multicasting. It is similar to the "udp"
+  stack in stacks.xml, but doesn't use streaming state transfer and flushing
+  author: Bela Ban
+-->
+
+<config xmlns="urn:org:jgroups"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="urn:org:jgroups http://www.jgroups.org/schema/JGroups-3.3.xsd">
+    <UDP
+         bind_addr="match-interface:eth0,match-interface:en0,site_local,loopback"
+
+         mcast_port="${jgroups.udp.mcast_port:45588}"
+         tos="8"
+         ucast_recv_buf_size="5M"
+         ucast_send_buf_size="640K"
+         mcast_recv_buf_size="5M"
+         mcast_send_buf_size="640K"
+         loopback="true"
+         max_bundle_size="64K"
+         max_bundle_timeout="30"
+         ip_ttl="${jgroups.udp.ip_ttl:8}"
+         enable_diagnostics="true"
+         thread_naming_pattern="cl"
+
+         timer_type="new3"
+         timer.min_threads="4"
+         timer.max_threads="10"
+         timer.keep_alive_time="3000"
+         timer.queue_max_size="500"
+
+         thread_pool.enabled="true"
+         thread_pool.min_threads="2"
+         thread_pool.max_threads="8"
+         thread_pool.keep_alive_time="5000"
+         thread_pool.queue_enabled="true"
+         thread_pool.queue_max_size="10000"
+         thread_pool.rejection_policy="discard"
+
+         oob_thread_pool.enabled="true"
+         oob_thread_pool.min_threads="1"
+         oob_thread_pool.max_threads="8"
+         oob_thread_pool.keep_alive_time="5000"
+         oob_thread_pool.queue_enabled="false"
+         oob_thread_pool.queue_max_size="100"
+         oob_thread_pool.rejection_policy="discard"/>
+
+    <PING timeout="2000"
+            num_initial_members="20"/>
+    <MERGE2 max_interval="30000"
+            min_interval="10000"/>
+    <FD_SOCK/>
+    <FD_ALL/>
+    <VERIFY_SUSPECT timeout="1500"  />
+    <BARRIER />
+    <pbcast.NAKACK2 xmit_interval="500"
+                    xmit_table_num_rows="100"
+                    xmit_table_msgs_per_row="2000"
+                    xmit_table_max_compaction_time="30000"
+                    max_msg_batch_size="500"
+                    use_mcast_xmit="false"
+                    discard_delivered_msgs="true"/>
+    <UNICAST3 xmit_interval="500"
+              xmit_table_num_rows="100"
+              xmit_table_msgs_per_row="2000"
+              xmit_table_max_compaction_time="60000"
+              conn_expiry_timeout="0"
+              max_msg_batch_size="500"/>
+    <pbcast.STABLE stability_delay="1000" desired_avg_gossip="50000"
+                   max_bytes="4M"/>
+    <pbcast.GMS print_local_addr="true" join_timeout="3000"
+                view_bundling="true"/>
+    <UFC max_credits="2M"
+         min_threshold="0.4"/>
+    <MFC max_credits="2M"
+         min_threshold="0.4"/>
+    <FRAG2 frag_size="60K"  />
+    <RSVP resend_interval="2000" timeout="10000"/>
+    <pbcast.STATE_TRANSFER />
+    <!-- pbcast.FLUSH  /-->
+</config>

template/xwiki/docker-entrypoint.sh

@@ -104,6 +104,17 @@ function restoreConfigurationFile() {
   fi
 }
 
+function enableClustering() {
+  echo 'Setting clustering...'
+  xwiki_set_properties 'observation.remote.enabled' 'true'
+  if [ \$CLUSTER_CHANNEL ]; then
+    echo "Setting cluster channel to \$CLUSTER_CHANNEL"
+    xwiki_set_properties 'observation.remote.channels' "\$CLUSTER_CHANNEL"
+  else
+    xwiki_set_properties 'observation.remote.channels' 'udp'
+  fi
+}
+
 function configure() {
   echo 'Configuring XWiki...'
 
@@ -138,6 +149,10 @@ function configure() {
     xwiki_set_properties 'solr.remote.url' "http://\$INDEX_HOST:\$INDEX_PORT/solr/xwiki"
   fi
 
+  if [ \$CLUSTER ]; then 
+    enableClustering
+  fi
+
   # If the files already exist then copy them to the XWiki's WEB-INF directory. Otherwise copy the default config
   # files to the permanent directory so that they can be easily modified by the user. They'll be synced at the next
   # start.