Drop rules

Based on your amount of available storage and rate limits, you might want to reduce the amount of metrics that you continue to store so that you're keeping only those metrics you need. For example, using Telemetry Usage Analyzer, you might find a metric has a low utilization score. Metrics with high volume and low utilization are candidates for dropping.

Use drop rules to omit incoming metrics based on labels, and have Chronosphere persist only those metrics you need. There are several ways to reduce metrics persisted by Chronosphere, depending on your use case:

To not send any metrics to Chronosphere, adjust what you send from client-side using mechanisms like relabel rules in the Collector.
To send metrics to Chronosphere so you can experiment with them in tools such as the Live Telemetry Analyzer, but not persist them, use drop rules.
To send metrics to Chronosphere and persist them, but optimize their storage with aggregation, use mapping rules.

The Collector scrapes data from an app, applies drop rules, and then publishes data to the Metrics Ingester.

Users cannot modify Terraform-managed resources in the Chronosphere app, with Chronoctl, or by using the API. Learn more.

Drop rules affect data from the point of rule creation onward. When you query for the metric:

Data can display in autocomplete searches for a period of approximately two hours.
Queries covering the time period before the drop rule took effect display the metric until the retention period expires.

View and filter created drop rules

To view the drop rules defined on your instance, you must have administrative privileges. In the navigation menu, click Go to Admin and then select Control > Drop Rules.

Use the Search rules text box to find a specific rule. This search looks for any text in any rule.

Select a value from the Status menu to filter for rules matching the selected status.

For information about viewing, copying, or downloading rule configurations, see Rule configuration.

Create a drop rule

Drop rules have these definition limitations:

The rule can't be longer than 4,096 characters.
A drop rule slug must contain only alphanumeric characters, dashes, or underscores. The allowed regular expression for matching is [a-zA-Z0-9-_]. Spaces aren't allowed.
Each rule name must be unique.

⚠️

The option to drop time series is based on data point values of 0 or 1. This type of drop rule can significantly reduce data points per second, but changes metrics from continuous series to sparse metrics. Adding a rule of this type can change the behavior of existing monitors or dashboards that use the target metric.

Use drop rules to drop the ingestion of certain metrics that you don't need to persist. For example dropping metrics from a specific cluster, or test data.

To create a drop rule, you must have administrative privileges:

In the navigation menu, click Go to Admin and then select Control > Drop Rules.
Click + Drop Rule.

If you have conditional drop rules, click Always Active. The drop rule consists of the following data model:
- A Name for the rule.
- A list of one or more Matchers, which are labels (a Key) with or without a specific value. You can use glob syntax in the Value field.
  
  When multiple labels are present, metrics must match each label:
  - A value of label1,label2 requires a metric matching both label1 and label2.
  - A value of {label1,label2} requires matching either label1 or label2.
  When allowing only particular metrics, you might need a double negation, which requires specific logical filtering:
```
keep: a==A && b==B
drop: !(a==A && b==B)
```
  In combination, this logic leads to a drop rule where !a==A || !b==B --> a!=A || b!=B.
  
  Comma-separated lists can't include spaces after commas. Rules with a space after a comma don't evaluate.
Click Review.
Review the rule to ensure it's correct.
Select the checkbox for I have reviewed the proposed changes and they look correct.
Click Save to finish, or Back to Edit to change the rule.

Drop rules can have multiple filter conditions on different labels, making it possible to drop a subset of the series matching a particular metric name. Use this if you identify a case where only a subset of the metric's data is used. For example, if a metric is used in an alert but examines only series related to error statuses, you can drop non-error status series.

Disable a drop rule

Users cannot modify Terraform-managed resources in the Chronosphere app, with Chronoctl, or by using the API. Learn more.

To disable an existing drop rule in the Chronosphere app, you must have administrative privileges:

In the navigation menu click Go to Admin and then select Control > Drop Rules.
Select the rule you want to disable from the list.
Toggle the rule to the Disabled state.
Click Save.

To re-enable the rule, use the previous steps and instead toggle Always Active.

Delete a drop rule

Use one of the following methods to delete unnecessary drop rules.

In the navigation menu select Shaping > Drop Rules.
Select the rule you want to delete from the list.
Click the delete icon to delete the rule.

Create a conditional drop rule

This feature isn't available to all customers.

Use a conditional drop rule to drop the ingestion of certain metrics when nearing your ingestion rate limit to prevent Chronosphere dropping other essential metrics due to hitting rate limits. For example, you can drop metrics from a source when it sends a burst of data.

Create a conditional drop rule dialog

To create a conditional drop rule:

In the navigation menu, click Go to Admin and then select Control > Drop Rules.
Click + Drop Rule.
Click the Conditional tab. The drop rule consists of the following data model:
- A title for the rule.
- A list of one or more labels with or without a specific value. You can use glob (opens in a new tab) syntax in the value field. When multiple labels are present, metrics must match each label.
- At what percentage of your licensed limits to activate the rule.
- A time interval (in minutes) for comparison against your licensed limits to reactivate the rule.
Click Save.

Mapping rules Evaluation failures