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Shaping Impact Preview lets you create new aggregation rules to preview the impact of a rule on your overall system. This helps prevent breaking changes and ensure the rules you create operate as expected. A rule created for preview purposes lets you profile the impact of the rule, but isn’t enabled in your system and doesn’t affect your stored data. Knowing the impact of a rule, and whether it accomplishes the needed task can be difficult. Shaping impact preview uses the existing rollup or mapping aggregation rule creation system to show you how your rule affects your Chronosphere Observability Platform installation before you apply the rule and change your data or stored time series.

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Preview a rule’s shaping impact

Rules in preview mode display in the Aggregation Rules UI similar to rules already in use. Rules in preview mode use a different background color, and have a Preview label next to the rule type in the Name column. When a preview rule is added, but hasn’t finished impact calculations, the shaping impact columns display calculating. Completed impact calculations display under Rule Efficiency, Matched Impact (if you’re using a matched writes license), and System Persisted Impact. Utility Score isn’t available for rules in preview mode because the Output metric can’t be used until the rule is enabled.

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Create a preview rule

Creating a preview rollup or mapping rule requires adding a configuration variable to the rule creation file called mode. The mode variable has two states:
  • preview: This rule is in a preview state, and doesn’t affect data being mapped, rolled up, or added to storage.
  • enabled: This rule is active and affecting incoming data.
If mode isn’t present, the rule defaults to the enabled state. For mapping or rollup rules created with Chronoctl, define mode in the spec section of the rule definition file. 
mode: PREVIEW
For rollup rules created with Terraform, add: 
# The operational mode for this rule.
mode = preview

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Change a rule from preview to enabled

Preview rules use the same definition files as active rules. To change a rule from preview to enabled:
  1. In the definition file, change the value of mode from preview to enabled.
  2. Save the file.
  3. Apply the updated definition.
The rule begins affecting data, and the Preview notice doesn’t display in the Aggregation Rules UI.