8.2. Node Attribute Expressions

⁠8.2. Node Attribute Expressions

Expressions are rule conditions based on the values of node attributes.

Table 8.2. Attributes of an expression Element

Field	Default	Description
`id`		A unique name for the expression (required)
`attribute`		The node attribute to test (required)
`type`	The default type for `lt`, `gt`, `lte`, and `gte` operations is `number` if either value contains a decimal point character, or `integer` otherwise. The default type for all other operations is `string`. If a numeric parse fails for either value, then the values compared as type `string`.	How the node attributes should be compared. Allowed values are `string`, `integer`, `number`, and `version`. `integer` truncates floating-point values if necessary before performing an integer comparison. `number` performs a floating-point comparison.
`operation`		The comparison to perform (required). Allowed values: `lt:` True if the node attribute value is less than the comparison value `gt:` True if the node attribute value is greater than the comparison value `lte:` True if the node attribute value is less than or equal to the comparison value `gte:` True if the node attribute value is greater than or equal to the comparison value `eq:` True if the node attribute value is equal to the comparison value `ne:` True if the node attribute value is not equal to the comparison value `defined:` True if the node has the named attribute `not_defined:` True if the node does not have the named attribute
`value`		User-supplied value for comparison (required for operations other than `defined` and `not_defined`)
`value-source`	`literal`	How the `value` is derived. Allowed values: `literal`: `value` is a literal string to compare against `param`: `value` is the name of a resource parameter to compare against (only valid in location constraints) `meta`: `value` is the name of a resource meta-attribute to compare against (only valid in location constraints)

⁠ In addition to custom node attributes defined by the administrator, the cluster defines special, built-in node attributes for each node that can also be used in rule expressions.

⁠

Table 8.3. Built-in Node Attributes

Name	Value
`#uname`	Node name
`#id`	Node ID
`#kind`	Node type. Possible values are `cluster`, `remote`, and `container`. Kind is `remote` for Pacemaker Remote nodes created with the `ocf:pacemaker:remote` resource, and `container` for Pacemaker Remote guest nodes and bundle nodes
`#is_dc`	"true" if this node is a Designated Controller (DC), "false" otherwise
`#cluster-name`	The value of the `cluster-name` cluster property, if set
`#site-name`	The value of the `site-name` node attribute, if set, otherwise identical to `#cluster-name`
`#role`	The role the relevant promotable clone resource has on this node. Valid only within a rule for a location constraint for a promotable clone resource.