Chapter 6. Setting Up Data Grid Clusters

PING, or UDPPING is a generic JGroups discovery mechanism that uses dynamic multicasting with the UDP protocol.

When joining, nodes send PING requests to an IP multicast address to discover other nodes already in the Data Grid cluster. Each node responds to the PING request with a packet that contains the address of the coordinator node and its own address. C=coordinator’s address and A=own address. If no nodes respond to the PING request, the joining node becomes the coordinator node in a new cluster.

<PING num_discovery_runs="3"/>

TCPPING is a generic JGroups discovery mechanism that uses a list of static addresses for cluster members.

With TCPPING, you manually specify the IP address or hostname of each node in the Data Grid cluster as part of the JGroups stack, rather than letting nodes discover each other dynamically.

<TCP bind_port="7800" />
<TCPPING timeout="3000"
         initial_hosts="${jgroups.tcpping.initial_hosts:hostname1[port1],hostname2[port2]}"
          port_range="0"
          num_initial_members="3"/>

MPING uses IP multicast to discover the initial membership of Data Grid clusters.

You can use MPING to replace TCPPING discovery with TCP stacks and use multicasing for discovery instead of static lists of initial hosts. However, you can also use MPING with UDP stacks.

<MPING mcast_addr="${jgroups.mcast_addr:228.6.7.8}"
       mcast_port="${jgroups.mcast_port:46655}"
       num_discovery_runs="3"
       ip_ttl="${jgroups.udp.ip_ttl:2}"/>

Gossip routers provide a centralized location on the network from which your Data Grid cluster can retrieve addresses of other nodes.

You inject the address (IP:PORT) of the Gossip router into Data Grid nodes as follows:

<TCP bind_port="7800" />
<TCPGOSSIP timeout="3000"
           initial_hosts="${GossipRouterAddress}"
           num_initial_members="3" />

JDBC_PING uses shared databases to store information about Data Grid clusters. This protocol supports any database that can use a JDBC connection.

Nodes write their IP addresses to the shared database so joining nodes can find the Data Grid cluster on the network. When nodes leave Data Grid clusters, they delete their IP addresses from the shared database.

<JDBC_PING connection_url="jdbc:mysql://localhost:3306/database_name"
           connection_username="user"
           connection_password="password"
           connection_driver="com.mysql.jdbc.Driver"/>

JGroups DNS_PING queries DNS servers to discover Data Grid cluster members in Kubernetes environments such as OKD and Red Hat OpenShift.

<dns.DNS_PING dns_query="myservice.myproject.svc.cluster.local" />

Data Grid includes default JGroups stacks that use discovery protocol implementations that are specific to cloud providers.

Providing Dependencies for Cloud Discovery Protocols

To use NATIVE_S3_PING, GOOGLE_PING2, or AZURE_PING cloud discovery protocols, you need to provide dependent libraries to Data Grid.

You can then configure the cloud discovery protocol as part of a JGroups stack file or with system properties.

When you extend a JGroups stack, inheritance attributes let you adjust protocols and properties in the stack you are extending.

Use the following properties to customize JGroups cluster transport.

Use the following properties to configure JGroups discovery protocols for hosted platforms.

To secure cluster traffic, you configure Data Grid nodes to encrypt JGroups message payloads with secret keys.

Data Grid nodes can obtain secret keys from either:

Asymmetric encryption secures cluster traffic as follows:

SYM_ENCRYPT, on the other hand, is faster than ASYM_ENCRYPT because nodes do not need to exchange keys with the cluster coordinator. A potential drawback to SYM_ENCRYPT is that there is no configuration to automatically generate new secret keys when cluster membership changes. Users are responsible for generating and distributing the secret keys that nodes use to encrypt cluster traffic.

Configure Data Grid clusters to generate and distribute secret keys that encrypt JGroups messages.

[org.infinispan.CLUSTER] ISPN000078: Starting JGroups channel cluster with stack <encrypted_stack_name>

Data Grid nodes can join the cluster only if they use ASYM_ENCRYPT and can obtain the secret key from the coordinator node. Otherwise the following message is written to Data Grid logs:

[org.jgroups.protocols.ASYM_ENCRYPT] <hostname>: received message without encrypt header from <hostname>; dropping it

Configure Data Grid clusters to encrypt JGroups messages with secret keys from keystores that you provide.

<infinispan>
  <jgroups>
    <!-- Creates a secure JGroups stack named "encrypt-tcp" that extends the default TCP stack. -->
    <stack name="encrypt-tcp" extends="tcp">
      <!-- Adds a keystore from which nodes obtain secret keys. -->
      <!-- Uses the stack.combine and stack.position attributes to insert SYM_ENCRYPT into the default TCP stack after VERIFY_SUSPECT. -->
      <SYM_ENCRYPT keystore_name="myKeystore.p12"
                   keystore_type="PKCS12"
                   store_password="changeit"
                   key_password="changeit"
                   alias="myKey"
                   stack.combine="INSERT_AFTER"
                   stack.position="VERIFY_SUSPECT"/>
    </stack>
  </jgroups>
  <cache-container name="default" statistics="true">
    <!-- Configures the cluster to use the JGroups stack. -->
    <transport cluster="${infinispan.cluster.name}"
               stack="encrypt-tcp"
               node-name="${infinispan.node.name:}"/>
  </cache-container>
</infinispan>

[org.infinispan.CLUSTER] ISPN000078: Starting JGroups channel cluster with stack <encrypted_stack_name>

Data Grid nodes can join the cluster only if they use SYM_ENCRYPT and can obtain the secret key from the shared keystore. Otherwise the following message is written to Data Grid logs:

[org.jgroups.protocols.SYM_ENCRYPT] <hostname>: received message without encrypt header from <hostname>; dropping it