crm_attribute

crm_attribute is a command-line tool from the crmsh (Cluster Resource Manager Shell) suite used in Pacemaker clusters. It allows administrators to query, set, and remove dynamic attributes stored in the Cluster Information Base (CIB). These attributes can be used to influence cluster behavior, store configuration flags, or serve as markers for custom policies.

Purpose

• Dynamic Configuration: Modify and update cluster-wide or node-specific attributes on the fly, which can affect resource allocation, priority, or other policy decisions.

• Monitoring and Troubleshooting: Query existing attributes to help diagnose cluster issues or verify that configuration changes have taken effect.

• Automation and Scripting: Integrate attribute management into scripts for automated cluster management and operational tasks.

Basic Syntax

crm_attribute [options]

Without any options, it may list current attributes. Common operations include listing, setting, and unsetting attributes.

Common Options

• -l, --list List all the currently defined attributes in the cluster.

  crm_attribute -l

• -S, --set Set or update an attribute by specifying a key-value pair.

  crm_attribute -S attribute_name=attribute_value

  Example:

  crm_attribute -S maintenance=true

  This command sets the attribute maintenance to true across the cluster.

• -U, --unset Remove a specific attribute.

  crm_attribute -U attribute_name

  Example:

  crm_attribute -U maintenance

  This command removes the maintenance attribute.

• -h, --help Display help and usage information.

  crm_attribute --help

Example Usage

1. Listing Attributes: To view all current attributes in the cluster:

   crm_attribute -l

2. Setting an Attribute: To mark the cluster as in maintenance mode:

   crm_attribute -S maintenance=true

   This attribute might be used by other policies or scripts to modify resource behavior during maintenance windows.

3. Unsetting an Attribute: When maintenance is complete, remove the attribute:

   crm_attribute -U maintenance

Conclusion

crm_attribute provides a flexible and dynamic way to manage custom attributes within a Pacemaker cluster. By allowing administrators to list, set, and remove attributes directly from the command line, it supports both manual configuration and automated scripts—helping to tailor cluster behavior and assist in monitoring and troubleshooting.