Configure cluster resources

A cluster resource is an instance of a program, an application, or data to be managed by the cluster service. These resources are abstracted by agents that provide a standard interface for managing the resource in a cluster environment.

To ensure that resources remain healthy, you can add a monitoring operation to a resource’s definition. If you do not specify a monitoring operation for a resource, one is added by default. You can determine the behavior of a resource in a cluster by configuring constraints for that resource. You can configure the following categories of constraints:

  • location constraints - A location constraint determines which nodes a resource can run on. Determining which nodes a resource can run on.
  • order constraints - An ordering constraint determines the order in which the resources run.
  • colocation constraints - A colocation constraint determines where resources will be placed relative to other resources.

As a shorthand for configuring a set of constraints that will locate a set of resources together and ensure that the resources start sequentially and stop in reverse order, Pacemaker supports the concept of resource groups. After you have created a resource group, you can configure constraints on the group itself just as you configure constraints for individual resources.

The format for the command to create a cluster resource is as follows:

# pcs resource create resource_id [standard:[provider:]]type [resource_options] [op operation_action operation_options [operation_actionoperation options]...] [meta meta_options...] [clone [clone_id] [clone_options] | promotable [clone_id] [clone_options] [--wait[=n]]

Key cluster resource creation options include the following:

  • The --before and --after options specify the position of the added resource relative to a resource that already exists in a resource group.
  • Specifying the --disabled option indicates that the resource is not started automatically.

There is no limit to the number of resources you can create in a cluster.

Resource creation examples
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The following command creates a resource with the name VirtualIP of standard ocf, provider heartbeat, and type IPaddr2. The floating address of this resource is 192.168.0.120, and the system checks whether the resource is running every 30 seconds.

# pcs resource create VirtualIP ocf:heartbeat:IPaddr2 ip=192.168.0.120 cidr_netmask=24 op monitor interval=30s

Alternately, you can omit the standard and provider fields and use the following command. This will default to a standard of ocf and a provider of heartbeat.

# pcs resource create VirtualIP IPaddr2 ip=192.168.0.120 cidr_netmask=24 op monitor interval=30s

Delete a configured resource
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Delete a configured resource with the following command.

# pcs resource delete resource_id

For example, the following command deletes an existing resource with a resource ID of VirtualIP.

# pcs resource delete VirtualIP

You can delete multiple resources with a single command. The following command deletes an existing resource with a resource ID of resource1 and an existing resource with a resource ID of resource2.

# pcs resource delete resource1 resource2