This article applies to:
- Visualizing Data
- Product edition: All
- Feature Category: Charts
When using Tanzu Observability it can be useful to display the threshold for an alert, to visualize when an alert has crossed an acceptably defined limit.
In the alert editor, a chart displays the time series values entered into the display expression field.
Note: If the display expression is not populated, the display expression field will be populated with the alert condition values.
When defining an threshold to be used in an alert, we need to define an expression that will help represent this when observing charts. One method to achieve this is to use the Collect () function. The
collect() function is a convenience function that combines multiple expressions into a single expression.
To use the
collect() function we can create a query in the following manner. collect(<display expression>, <threshold integer>).
This in conjunction with the Alert Condition will not only provide for what we are alerting against, it will also now display the Display Expression of the threshold to visualize the limit that we should not expect to cross, for the condition that has been defined.
Please refer to the chart below for an example:
Note: The preceding excerpts/Messages are only examples. Date, time, and
environmental variables may vary depending on your environment.
Additionally the example method of using the collect() function can also be used in queries, when you'd like to display threshold lines in a single query line.