condition_from_expression_persistent

Create a new condition that persists across runs.

⚙️ Compatible targets: Linux

Parameters

NameDocumentation
conditionThe condition prefix.

This parameter is required.
expressionThe expression evaluated to create the condition (use 'any' to always evaluate to true).

This parameter is required.
durationThe persistence suffix in minutes.

This parameter is required.

Example

method: condition_from_expression_persistent
params:
  expression: VALUE
  duration: VALUE
  condition: VALUE

Documentation

This method evaluates an expression (=condition combination), and produces a ${condition}_true or a ${condition}_false condition depending on the result on the expression, which will lasts for the Duration time:

  • This method always result with a success outcome status
  • If the expression evaluation results in a "defined" state, this will define a ${condition}_true condition,
  • If the expression evaluation results in an "undefined" state, this will produce a ${condition}_false condition.

Calling this method with a condition expression transforms a complex expression into a single class condition.

The created condition is global to the agent and is persisted across runs. The persistence duration is controlled using the parameter Duration which defines for how long the target condition will be defined (in minutes). Note that there is no way to persist indefinitely.

Example:

If you want to check if a condition evaluates to true, like checking that you are on Monday, 2am, on RedHat systems, and make it last one hour you can use the following policy

condition_from_expression_persistent_("backup_time", "Monday.redhat.Hr02", "60")

The method will define:

  • In any case:
    • condition_from_expression_persistent_backup_time_kept
    • condition_from_expression_persistent_backup_time_reached
  • And:
    • backup_time_true if the system is a RedHat like system, on Monday, at 2am, and will persist for Duration minutes,
    • backup_time_false if the system not a RedHat like system, or it's not Monday, or it's not 2am
    • no extra condition if the expression is invalid (cannot be parsed)
Notes:

Rudder will automatically "canonify" the given Condition prefix at execution time, which means that all non [a-zA-Z0-9_] characters will be replaced by an underscore.