crm_resource

crm_resource is a command-line utility that is part of the crmsh (Cluster Resource Manager Shell) toolkit used to manage and interact with resources in a Pacemaker-managed high-availability cluster. It provides administrators with the ability to query the status of resources, as well as perform operations like starting, stopping, or restarting resources directly from the command line.

Purpose

• Resource Querying: crm_resource allows you to obtain detailed status information for individual cluster resources, including their current state, location, and any pending operations or failures.

• Resource Control: In addition to status checks, it can be used to control resources by initiating actions such as starting, stopping, or restarting a resource, which is useful for troubleshooting or performing manual failovers.

• Scripting and Automation: The command's output can be used in scripts to monitor cluster health and to trigger automated responses if certain resources are found to be in an unexpected state.

Basic Syntax

crm_resource [options] <command> <resource_name>

• Options: Various options to control verbosity or output formatting.

• Command: The action to be performed (e.g., status, start, stop, restart).

• Resource Name: The name of the resource as defined in the cluster configuration.

Common Commands

• Query Resource Status:

  crm_resource --resource <resource_name> --query

  Example:

  crm_resource --resource my-web-server --query

  This command returns the current status of the resource my-web-server, such as whether it is running, stopped, or in a failed state.

• Start a Resource:

  crm_resource --resource <resource_name> --action start

  Example:

  crm_resource --resource my-database --action start

  This initiates the start operation for the resource my-database.

• Stop a Resource:

  crm_resource --resource <resource_name> --action stop

  Example:

  crm_resource --resource my-database --action stop

  This stops the resource my-database.

• Restart a Resource:

  crm_resource --resource <resource_name> --action restart

  Example:

  crm_resource --resource my-app --action restart

  This command restarts the resource my-app.

• Get Resource Metadata:

  crm_resource --resource <resource_name> --meta-data

  Example:

  crm_resource --resource my-web-server --meta-data

  This displays the metadata and configuration details for my-web-server, providing insights into its configuration parameters and constraints.

Example Workflow

1. Check the status of a resource:

   crm_resource --resource my-ip --query

   This helps determine if the resource is active, stopped, or in an error state.

2. Restart a resource that is not performing correctly:

   crm_resource --resource my-ip --action restart

   Restarting can often resolve transient issues.

3. Retrieve metadata for troubleshooting:

   crm_resource --resource my-ip --meta-data

   This command helps administrators understand the configuration details, which can be compared against expected settings when diagnosing issues.

Conclusion

crm_resource is a versatile and essential tool for administrators managing Pacemaker clusters. It provides direct control over individual cluster resources, enabling effective monitoring, troubleshooting, and management through a consistent command-line interface. Whether you need to query resource status, start or stop resources, or examine detailed metadata, crm_resource helps ensure that your high-availability cluster operates smoothly and reliably.