# Clustering configuration The following configuration items define how Liberator participates in a cluster. Want to know more about clustering? [See here](liberator-clustering.md). **📌 NOTE**\ "_this Liberator_" means the Liberator for which you are defining the configuration. "_this node_" means the cluster node that this Liberator represents. ## add-cluster-node `add-cluster-node` identifies a Liberator in the cluster. **💡 TIP**\ For more about how to use `add-cluster-node`, see [Clustering Liberators without the Caplin Deployment Framework](liberator-set-up-a-cluster-of-liberators.md#clustering-liberators-without-the-caplin-deployment-framework) in How can I.. [Set up a cluster of Liberators](liberator-set-up-a-cluster-of-liberators.md). **Syntax:** ``` add-cluster-node xref:cluster-addr[cluster-addr] [string] xref:cluster-port[cluster-port] [integer] end-cluster-node ``` | Option | Type | Default | Description | | --- | --- | --- | --- | | `cluster-addr` | string | `127.0.0.1` | The network interface address or hostname of the cluster node. In the [Caplin Platform Deployment Framework](../deployment-framework/index.md), the configuration macros `LIBERATOR${THIS_LEG}_HOST` and `LIBERATOR${OTHER_LEG}_HOST` specify the `cluster-addr` values. Clustering is used in the Deployment Framework to support failover capability. You normally use the [`./dfw hosts`](../deployment-framework/cdf-the-deployment-framework-command-utility-dfw.md#hosts) command to set up the hostnames in the macros. See [Configuring server hostnames](../deployment-framework/cdf-set-up-server-failover-capability.md#configuring-server-hostnames) in How can I... [Set up server failover capability](../deployment-framework/cdf-set-up-server-failover-capability.md), and [Change server hostnames](../deployment-framework/cdf-change-server-specific-configuration.md#change-server-hostnames) in How can I ... [Change server-specific configuration](../deployment-framework/cdf-change-server-specific-configuration.md). Also see Deployment Framework [Configuration macros and items](../deployment-framework/cdf-configuration-macros-and-items.md). | | `cluster-port` | integer | `2333` | The network port number of the cluster node. This port is used for cluster-related communication between the Liberator and the other Liberators in the cluster. In the [Caplin Platform Deployment Framework](../deployment-framework/index.md), the configuration macros `LIBERATOR${THIS_LEG}_CLUSTER_PORT` and `LIBERATOR${OTHER_LEG}_CLUSTER_PORT` specify the `cluster-port` values. See [Clustering Liberators in the Caplin Deployment Framework](liberator-set-up-a-cluster-of-liberators.md#clustering-liberators-in-the-caplin-deployment-framework) in How can I ... [Set up a cluster of Liberators](liberator-set-up-a-cluster-of-liberators.md). Also see Deployment Framework [Configuration macros and items](../deployment-framework/cdf-configuration-macros-and-items.md). | ## cluster-heartbeat-slack-time `cluster-heartbeat-slack-time` When this Liberator doesn’t receive an expected cluster heartbeat (see [cluster-heartbeat-time](#cluster-heartbeat-time)) from another Liberator in the cluster, it waits `cluster-heartbeat-slack-time` seconds before disconnecting from the cluster and trying to reconnect to it. Unlike `cluster-heartbeat-time`, the value of `cluster-heartbeat-slack-time` is not compared by the Liberators in the cluster. **Syntax:** `cluster-heartbeat-slack-time ` **Type:** integer **Default value:** `5` seconds ## cluster-heartbeat-time `cluster-heartbeat-time` specifies the time in seconds between each cluster heartbeat. The Liberators forming a cluster exchange heartbeat messages at regular intervals, allowing each of them to check that all the others are still present. If the cluster heartbeat times out, this Liberator waits [cluster-heartbeat-slack-time](#cluster-heartbeat-slack-time) and then disconnects from the cluster and tries to reconnect to it. When all the Liberators in the cluster have initially connected, they compare their `cluster-heartbeat-time` values and use the lowest. **📌 NOTE**\ In the [Caplin Platform Deployment Framework](../deployment-framework/index.md), you use a configuration macro `LIBERATOR_CLUSTER_HEARTBEAT_TIME` to specify Liberator’s `cluster-heartbeat-time`. See [Clustering Liberators in the Caplin Deployment Framework](liberator-set-up-a-cluster-of-liberators.md#clustering-liberators-in-the-caplin-deployment-framework) in How can I ... [Set up a cluster of Liberators](liberator-set-up-a-cluster-of-liberators.md), and Deployment Framework [Configuration macros and items](../deployment-framework/cdf-configuration-macros-and-items.md). **Syntax:** `cluster-heartbeat-time ` **Type:** integer **Default value:** `15` seconds The minimum allowed value is 1 second. ## cluster-index `cluster-index` specifies the index number of this cluster node. The index number uniquely identifies this Liberator within the cluster. It states which of the [add-cluster-node](#add-cluster-node) items this node represents. Index numbers start at 0 and correspond to the order of the [add-cluster-node](#add-cluster-node) items in the configuration file. **📌 NOTE**\ In the [Caplin Platform Deployment Framework](../deployment-framework/index.md), you use a configuration macro `LIBERATOR_CLUSTER_NODE_INDEX` to specify Liberator’s `cluster-index`. See [Clustering Liberators in the Caplin Deployment Framework](liberator-set-up-a-cluster-of-liberators.md#clustering-liberators-in-the-caplin-deployment-framework) in How can I ... [Set up a cluster of Liberators](liberator-set-up-a-cluster-of-liberators.md), and Deployment Framework [Configuration macros and items](../deployment-framework/cdf-configuration-macros-and-items.md). **Syntax:** `cluster-index ` **Type:** integer **Default value:** `0` ## cluster-packet-logfile `cluster-packet-logfile` specifies the name of the log file in which message packets passed between this Liberator and other nodes in the Liberator cluster are recorded. The filename can contain the parameter `%a`, which is replaced at run-time by this Liberator’s DataSource [`application-name`](../datasource/datasource-run-time-environment-configuration.md#application-name). The log file is located in Liberator’s `var` directory (the `/servers/Liberator/var` directory in the Deployment Framework). The log file’s format is the same binary format used for the standard DataSource packet log (see [`datasrc-pkt-log`](../datasource/datasource-datasource-peers-configuration-part-2.md#datasrc-pkt-log) in [DataSource peers configuration part 2](../datasource/datasource-datasource-peers-configuration-part-2.md)), so you need to use the [logcat utility](../datasource/datasource-view-packet-logs-using-logcat.md) to read it. **⚠️ WARNING**\ Only configure `cluster-packet-logfile` when you need to troubleshoot your Liberator cluster. Cluster packet logs can quite quickly become very large, so you should only enable logging of this information for debugging purposes. **Syntax:** `cluster-packet-logfile ` **Type:** string **Default value:** (none, but this configuration item is optional - if it’s not present then cluster packets aren’t logged) --- **See also:** * How can I... [Set up a cluster of Liberators](liberator-set-up-a-cluster-of-liberators.md) * [Liberator clustering features and concepts](liberator-clustering.md)