25.2.3.11. Clustered Instances

25.2.3.11.1. Launch Clustered JBoss EAP 6 AMIs
Summary

This topic covers the steps required to launch clustered JBoss EAP 6 AMIs.

Prerequisites

Warning

Running a JBoss EAP 6 cluster in a subnet with network mask smaller than 24 bits or spanning multiple subnets complicates acquiring a unique server peer ID for each cluster member.
Refer to the JBOSS_CLUSTER_ID variable for information on how to make such a configuration work reliably: Section 25.4.1, “Permanent Configuration Parameters”.

Important

The auto-scaling Amazon EC2 feature can be used with JBoss EAP 6 cluster nodes. However, ensure it is tested before deployment. You should ensure that your particular workloads scale to the desired number of nodes, and that the performance meets your needs for the instance type you are planning to use (different instance types receive a different share of the EC2 cloud resources).
Furthermore, instance locality and current network/storage/host machine/RDS utilization can affect performance of a cluster. Test with your expected real-life loads and try to account for unexpected conditions.

Warning

The Amazon EC2 scale-down action terminates the nodes without any chance to gracefully shut down, and, as some transactions might be interrupted, other cluster nodes (and load balancers) will need time to fail over. This is likely to impact your application users' experience.
It is recommended that you either scale down the application cluster manually by disabling the server from the mod_cluster management interface until processed sessions are completed, or shut down the JBoss EAP 6 instance gracefully (SSH access to the instance or JON can be used).
Test that your chosen procedure for scaling-down does not lead to adverse effects on your users' experience. Additional measures might be required for particular workloads, load balancers and setups.

Procedure 25.13. Launch Clustered JBoss EAP 6 AMIs

  1. Select an AMI.
  2. Define the desired number of instances (the cluster size).
  3. Select the VPC and instance type.
  4. Click on Security Group.
  5. Ensure that all traffic from the JBoss EAP 6 cluster subnet is allowed.
  6. Define other restrictions as desired.
  7. Add the following into the User Data field:

    Example 25.7. Example User Data Field

    ## mod cluster proxy addresses
MOD_CLUSTER_PROXY_LIST=10.0.0.4:7654

## clustering setup
JBOSS_JGROUPS_S3_PING_SECRET_ACCESS_KEY=<your secret key>
JBOSS_JGROUPS_S3_PING_ACCESS_KEY=<your access key>
JBOSS_JGROUPS_S3_PING_BUCKET=<your bucket name>

## password to access admin console
JBOSSAS_ADMIN_PASSWORD=<your password for opening admin console>

## database credentials configuration
JAVA_OPTS="$JAVA_OPTS -Ddb.host=instancename.something.rds.amazonaws.com -Ddb.database=mydatabase -Ddb.user=<user> -Ddb.passwd=<pass>"

## subnet prefix this machine is connected to
SUBNET=10.0.1.

#### to run the example no modifications below should be needed ####
PORTS_ALLOWED="1024:65535"
JBOSS_IP=`hostname | sed -e 's/ip-//' -e 'y/-/./'` #listen on public/private EC2 IP address

cat > $USER_SCRIPT << "EOF"
## Get the application to be deployed from an Internet URL
# mkdir -p /usr/share/java/jboss-ec2-eap-applications
# wget https://<your secure storage hostname>/<path>/<app name>.war -O /usr/share/java/jboss-ec2-eap-applications/<app name>.war

## install the JDBC driver as a core module
yum -y install mysql-connector-java
mkdir -p /usr/share/jbossas/modules/com/mysql/main
cp -v /usr/share/java/mysql-connector-java-*.jar /usr/share/jbossas/modules/com/mysql/main/mysql-connector-java.jar

cat > /usr/share/jbossas/modules/com/mysql/main/module.xml <<"EOM"
<?xml version="1.0" encoding="UTF-8"?>
<module xmlns="urn:jboss:module:1.0" name="com.mysql">
   <resources>
      <resource-root path="mysql-connector-java.jar"/>
   </resources>
   <dependencies>
      <module name="javax.api"/>
   </dependencies>
</module>
EOM

cat > $USER_CLI_COMMANDS << "EOC" 
## Deploy sample application from local filesystem
deploy --force /usr/share/java/jboss-ec2-eap-samples/cluster-demo.war

## ExampleDS configuration for MySQL database
data-source remove --name=ExampleDS
/subsystem=datasources/jdbc-driver=mysql:add(driver-name="mysql",driver-module-name="com.mysql")
data-source add --name=ExampleDS --connection-url="jdbc:mysql://${db.host}:3306/${db.database}" --jndi-name=java:jboss/datasources/ExampleDS --driver-name=mysql --user-name="${db.user}" --password="${db.passwd}"
/subsystem=datasources/data-source=ExampleDS:enable
/subsystem=datasources/data-source=ExampleDS:test-connection-in-pool
EOC

## this will workaround the problem that in a VPC, instance hostnames are not resolvable
echo -e "127.0.0.1\tlocalhost.localdomain localhost" > /etc/hosts
echo -e "::1\tlocalhost6.localdomain6 localhost6" >> /etc/hosts
for (( i=1 ; i<255 ; i++ )); do
   echo -e "$SUBNET$i\tip-${SUBNET//./-}$i" ;
done >> /etc/hosts

EOF
Result

The clustered JBoss EAP 6 AMIs have been configured and launched successfully.

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