- Alfresco installation on two nodes (each one will have its own Solr index)
- Database install on one node
- Contentstore being shared from one node
- Proxy load balancer (using Apache)
ArchitectureThis can be spread out on to many different server nodes if you wanted to. But, we'll show you how to do this on 3 servers:
- Alfresco install on alf1 node
- Alfresco install on alf2 node
- Database installation and shared NFS drive on db1 node
It is possible to do this on 2 servers (even 1 if you really wanted to) and have the database installed on one of the Alfresco servers but it's best for learning purposes to do it with 3 if you can. If you have enough resources locally, you can do this with VirtualBox or VMWare. For this article, I'll do it using AWS.
Logically speaking, an Alfresco cluster will have at least two Alfresco installations. Both installations will use a single database and will share a similarly configured connection. For my example, I am using MySQL. Both Alfresco installs will also use a single contentstore where the files are shared. But, each Solr will have to have its own indexes. Solr has index files that only pertain to its own local Solr install. Solr doesn't have the ability to use index files that could be shared among Solr installations.
I have built 3 virtual servers which are using Ubuntu 16.04 as OS:
- alf1 - 2 cpu's with 8GB of memory (hard drive space doesn't need to be more than the default 8GB that you get with an AWS instance)
- alf2 - 2 cpu's with 8GB of memory (same hard drive specs)
- db1 - 1 cpu with 4GB of memory (same hard drive specs)
Prepare ServersOnce you've built these three server, log in on each one and run updates and upgrades to get each system up to speed:
# sudo apt update && sudo apt upgrade
For the Alfresco servers make sure these ports are open in both AWS security group and in each server's firewall:
- alf1 and alf2: 8080, 8443 and 80
- db1: 3306, 2049 and 111
On alf1 and alf2 run this command to install the prerequisites for the Alfresco installation:
# sudo apt install libfontconfig1 libfontconfig1-dev libice-dev libice6 libsm-dev libsm6 libxrender-dev libxrender1 libxext-dev libxext6 libxinerama-dev libxinerama1 libcups2 libcups2-dev libglu1-mesa libglu1-mesa-dev libcairo2 libcairo2-dev
Install MySQLOn db1 install MySQL server:
# sudo apt install mysql-server
The MySQL server install should give you the opportunity to set the root password. For this article, I have set the password with 'Alfr3sc0'.
Open the MySQL client:
# mysql -u root -pAlfr3sc0
In the MySQL client, issue these commands to create the Alfresco database and set the proper permissions:
mysql> create database alfresco;
mysql> grant all privileges on alfresco.* to 'alfresco'@'alfresco' identified by 'Alfr3sc0';
Query OK, 0 rows affected, 1 warning (0.01 sec)
mysql> grant all privileges on alfresco.* to 'alfresco'@'172.30.1.197' identified by 'Alfr3sc0';
Query OK, 0 rows affected, 1 warning (0.01 sec)
mysql> grant all privileges on alfresco.* to 'alfresco'@'172.30.1.78' identified by 'Alfr3sc0';
Query OK, 0 rows affected, 1 warning (0.00 sec)
Install NFSOn db1 install the NFS server and set up the contentstore share:
# sudo apt install nfs-kernel-server
Create the Alfresco contentstore shared folder:
# mkdir -p alfresco/contentstore
Add the following endpoints for each Alfresco server.
# vi /etc/exports
Restart the NFS Server so that these configurations are in effect:
# service nfs-server restart
Issue the exportfs command to ensure that the correct shared folders are in effect:
# sudo exportfs -ra
On both alf1 and alf2 install the NFS clients:
# apt install nfs-common
Create the Alfresco Contentstore mount point folder:
# mkdir /mnt/alfresco-contentstore
In the /etc/fstab file create a pointer to the
# vi /etc/fstab
172.30.1.198:/alfresco/contentstore /mnt/alfresco-contentstore nfs rw,soft,intr,noatime,x-gvfs-show
Mount the mount points:
# mount -a
Check the output of the df command to ensure the mount points are active:
# df -kh
Test the mount points and make sure that your user can create a file there:
# cd /mnt/alfresco-contentstore/
# touch test
Install AlfrescoOn alf1 and alf2 install Alfresco.
For this article, I have used Alfresco 5.2.4 but this should work with any recent version of either Alfresco Enterprise or Community:
# ./alfresco-installer.bin --mode text
Set the following configurations (make sure the ip addresses shown reflect the database server ip address in your environment):
JDBC URL: [jdbc:postgresql://localhost/alfresco]: jdbc:mysql://172.30.1.198/alfresco?useUnicode=yes&characterEncoding=UTF-8
JDBC Driver: [org.postgresql.Driver]: org.gjm.mm.mysql.Driver
Database name: [alfresco]: alfresco
Install the MySQL jdbc jar to your tomcat/lib directories:
# wget http://central.maven.org/maven2/mysql/mysql-connector-java/5.1.42/mysql-connector-java-5.1.42.jar
In alfresco-global.properties (in the tomcat/shared/classes folder) set the dir.contentstore to use the mounted Alfresco Contentstore drive:
Start up alf1 and make sure it works as expected. To test, you should create a Share site, add a document and be able to successfully search for it. Follow these same steps for alf2 and test to see if you can find the same file there too -- in the expected folder and in search as well. With alf1 you can go ahead and add your license. The license info will be added to the database. Since both Alfresco installs are referencing the same database, the license info will be sufficient for both alf1 and alf2.
At a minimum, you should be able to log in to each Alfresco server. But, you will notice that if you log in on both alf1 and alf2 and then log out of alf1, you will still be logged in to alf2. This is because we are using multiple sessions for the same user which is not ultimately what we want. Go ahead and turn off both alf1 and alf2 Alfresco services. In the next section, we'll configure Hazelcast to enable session replication.
Share Cluster (session replication)To configure Hazelcast for session replication you only need to remove the .sample from custom-slingshot-application-context.xml.sample file in tomcat/shared/classes/alfresco/web-extension folder so that it becomes custom-slingshot-application-context.xml.
Inside this file, change the 192.168.0.* to your internal ip address of your Alfresco server. After you do this for both Alfresco nodes, go ahead and restart both of them one at a time. Once you've done that, you can then log in to both Alfresco nodes.
Then, log out of alf1 and do a refresh of alf2. On alf2 you should be redirected to the login page. This demonstrates that you are using the same session on both nodes.
For this to be a true application cluster, we need to use only one hostname to access Alfresco. This hostname will then redirect to either Alfresco node based on a load-balancer's configuration. For the hostname we'll use alfrescodemo.com. In your workstation add the following to your hosts file (for demonstration purposes):
The ip address above should point to your database server (this is where we'll install Apache). We'll use Apache to handle this from the database server.
Apache Proxy/Load BalancingOn the db1 node install Apache 2.4 and mod_jk:
# sudo apt install apache2 libapache2-mod-jk
Open the default host configuration 000-default.conf in /etc/apache2/sites-available and add the following:
ProxyPassReverse /share balancer://app
ProxyPass /share balancer://app stickysession=JSESSIONID|jsessionid nofailover=On
BalancerMember ajp://172.30.1.197:8009/share route=tomcat1
BalancerMember ajp://172.30.1.78:8009/share route=tomcat2
Save the file. In /etc/libapache2-mod-jk folder back up the workers.properties file and create a new one. In the new workers.properties file add the following (change the ip addresses to the ones you are using for alf1 and alf2 in your environment):
Save this file and restart Apache by issuing:
# service apache2 restart
On the alf1 and alf2 servers, make the following changes to the server.xml (in tomcat/conf):
<Connector port="80" URIEncoding="UTF-8" protocol="HTTP/1.1"
redirectPort="8443" maxHttpHeaderSize="32768" />
and change the following in the existing Engine stanza:
<Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat1">
Use jvmRoute="tomcat1" for alf1 and jvmRoute="tomcat2" for alf2.
In alfresco-global.properties make these changes:
In share-custom-config.xml (in tomcat/shared/classes/web-extension folder) change all mentions of: