Understanding and Creating Rules

Understanding and Creating Rules

Constraint rules are used to place value constraints on particular types of CA Configuration Automation elements, including the following:

• Rules in the Indicators, Verification Rules folder (Component Blueprints only)
• Parameters in the Parameters folder (Services only)
• Files and directories in the Managed, File System Overlay
• Registry keys and values in the Managed, Registry Overlay folder
• Parameters in the Parameter, Rules folder
• Parameters in the Configuration, Structure Classes folder
• Files in the Configuration folder

Constraint rules are always associated one-to-one with an element and can be either created in and inherited from the underlying Component Blueprint or created in and applied directly to a service instance. In addition to the explicit constraint rules that you create, there are also built-in CA Configuration Automation implicit constraint rules. For example, if you specify a particular value or data type for an element, CA Configuration Automation automatically creates an implicit Check Default or Verify Data Type rule.

Note: When possible, consider creating constraint rules within the Component Blueprint. You create the rule once, and it is automatically inherited by any service that uses the underlying Component Blueprint.

Constraint rules are initiated, viewed, and edited from the Rules field of the selected Component Blueprint.

The number of defined constraint rules or None is displayed in the brackets to the right of Rules. From the drop-down list, you can view a specific constraint rule, view all constraint rules, or add constraint rules.

• If you select Show All Rules, a new page is displayed showing a list of all constraint rules in table format. You can change the sort order of the table by clicking any of the table headings.
• If you select New Rule, the Rule attribute sheet is displayed.
• If you select a specific constraint rule, the name is displayed in the Rules field and the attribute sheet for that constraint rule is displayed. You can edit or delete most rules from the attribute sheet. The exception is that you cannot edit or delete CA Configuration Automation built-in or implicit rules, such as Check Default or Verify Data Type. You can only view these implicit rules.

When a default value is specified in a Component Blueprint, an implicit Check Default rule is automatically created. These default rules are informational (show in Rule Compliance as Information, with an icon), and let you know when a value is deviating from the recommended default value.

Explicitly defined constraint rules derive their value from the element itself or from one of the element's attributes. The available attributes and the value type vary for each element within CA Configuration Automation, so constraint rules vary significantly by element type. For example: