Overview of the Cluster Configuration Service

This topic provides an overview of the cluster configuration service.

The Spring Session for Tanzu GemFire cluster configuration service persists cluster configurations created by gfsh commands to the locators in a cluster and distributes the configurations to members of the cluster.

Why Use the Cluster Configuration Service

We highly recommend that you use the gfsh command line and the cluster configuration service as the primary mechanism to manage your cluster configuration. Specify configuration within a cache.xml file for only those items that cannot be specified or altered using gfsh. Using a common cluster configuration reduces the amount of time you spend configuring individual members and enforces consistent configurations when bringing up new members in your cluster. You no longer need to reconfigure each new member that you add to the cluster. You no longer need to worry about validating your cache.xml file. It also becomes easier to propagate configuration changes across your cluster and deploy your configuration changes to different environments.

You can use the cluster configuration service to:

• Save the configuration for an entire VMware Tanzu GemFire cluster.
• Restart members using a previously-saved configuration.
• Export a configuration from a development environment and migrate that configuration to create a testing or production system.
• Start additional servers without having to configure each server separately.
• Configure some servers to host certain regions and other servers to host different regions, and configure all servers to host a set of common regions.

Using the Cluster Configuration Service

To use the cluster configuration service in Tanzu GemFire, you must use dedicated, standalone locators in your deployment. You cannot use the cluster configuration service with co-located locators (locators running in another process such as a server) or in multicast environments.

The standalone locators distribute configuration to all locators in a cluster. Every locator in the cluster with --enable-cluster-configuration set to true keeps a record of all cluster-level and group-level configuration settings.

Note: The default behavior for gfsh is to create and save cluster configurations. You can deactivate the cluster configuration service by using the --enable-cluster-configuration=false option when starting locators.

You can load existing configuration into the cluster by using the gfsh import cluster-configuration command after starting up a locator.

Subsequently, any servers that you start with gfsh that have --use-cluster-configuration set to true will pick up the cluster configuration from the locator as well as any appropriate group-level configurations (for member groups they belong to). To deactivate the cluster configuration service on a server, you must start the server with the --use-cluster-configuration parameter set to false. By default, the parameter is set to true.

How the Cluster Configuration Service Works

When you use gfsh commands to create VMware Tanzu GemFire regions, disk-stores, and other objects, the cluster configuration service saves the configurations on each locator in the cluster. If you specify a group when issuing these commands, a separate configuration is saved containing only configurations that apply to the group.

When you use gfsh to start new VMware Tanzu GemFire servers, the locator distributes the persisted configurations to the new server. If you specify a group when starting the server, the server receives the group-level configuration in addition to the cluster-level configuration. Group-level configurations are applied after cluster-wide configurations; therefore you can use group-level to override cluster-level settings.

1. Developer or Administrator executes gfsh commands to configure the cluster.

2. gfsh saves the cluster information on the locators. Existing servers using cluster configuration are configured.

3. Developer or Administrator executes gfsh to add new members to the cluster.

4. New members request the configuration from a locator.

5. Locator distributes the configuration to new servers joining the cluster. Configuration includes regions, disk stores, and jar files,

gfsh Commands that Create Cluster Configurations

The following gfsh commands cause the configuration to be written to all locators in the cluster (the locators write the configuration to disk):

• configure pdx*
• create region
• alter region**
• alter runtime
• destroy region
• create index
• destroy index
• create disk-store
• destroy disk-store
• create async-event-queue
• alter async-event-queue
• destroy async-event-queue
• deploy jar
• undeploy jar
• create gateway-sender
• destroy gateway-sender
• create gateway-receiver
• destroy gateway-receiver
• alter query-service

* Note that the configure pdx command must be executed before starting your data members. This command does not affect any currently running members in the system. Data members (with cluster configuration enabled) that are started after running this command will pick up the new PDX configuration.

** If cluster configuration is enabled, the region this command is applied to must exist in the cluster configuration. If that is not the case, the command will fail saying the region does not exist.

gfsh Limitations

These are the configurations that you cannot create or alter using gfsh. These configurations must be within a cache.xml file or be applied by using the API:

• Client cache configuration

• You cannot directly modify the attributes of the following objects:

  • function
  • custom-load-probe
  • compressor
  • serializer
  • instantiator

  • pdx-serializer

    Note: The configure pdx command always specifies the org.apache.geode.pdx.ReflectionBasedAutoSerializer class. You cannot specify a custom PDX serializer in gfsh.

  • initializer

  • lru-heap-percentage
  • lru-memory-size
  • partition-resolver
  • partition-listener
  • transaction-listener
  • transaction-writer
• Adding or removing a TransactionListener
• Configuring a GatewayConflictResolver
• You cannot specify parameters and values for Java classes for the following:
  • gateway-listener
  • gateway-conflict-resolver
  • gateway-event-filter
  • gateway-transport-filter
  • gateway-event-substitution-filter

Deactivating the Cluster Configuration Service

If you do not want to use the cluster configuration service, start up your locator with the --enable-cluster-configuration parameter set to false or do not use standalone locators. You will then need to configure the cache (via cache.xml or API) separately on all your cluster members.