You can define a condition or a set of conditions to evaluate the performance metrics of your application in Step 2 of the Create New Health Rule wizard. Use the following options to evaluate complex conditions:

  • Expression builder embedded in the health rules wizard to create a condition based on a complex expression comprising multiple interdependent metrics.
  • Custom boolean expression to evaluate multiple conditions within a health rule. You can use the AND and OR operators in a boolean expression.

Create a Condition

  1. Click the dropdown list Use data from last <> min(s) and select a number between 1 and 120 minutes. The value you specify is the latest time interval during which data is collected to determine if there is a health violation.

    • If you plan to define a persistence threshold for the health rule condition, ensure that you define an evaluation time frame of 30 mins or less.
    • If you have already configured a condition in the Warning Criteria tab, you can copy the configuration from the Warning Criteria to the Critical Criteria tab using the Copy from Warning Criteria option. Similarly, you can copy the configuration from Critical Criteria to Warning Criteria using the Copy from Critical Criteria option.
  2. In the Critical Criteria tab, from the dropdown list, select one of the following:
    • All—if all of the conditions must evaluate as true to constitute a health violation. 
    • Any—if any of the conditions must evaluate as true to constitute a health violation. 
    • Custom—if a combination of conditions defined in a boolean expression must evaluate as true to constitute a health violation.

      See Create a Custom Boolean expression.
  3. Click + Add Condition to add a new condition component.
    A condition row listing the configuration details appears.
  4. Configure the Condition as required.
  5. Repeat steps 3 and 4 to add more conditions. You can add a maximum of 8 conditions. Conditions are designated as A, B, C, and so on.
  6. If you have defined multiple conditions and want the health rule to evaluate a combination of conditions, define a Custom Boolean expression.
  7. If you want to define a condition in the Warning Criteria tab, click the Warning Criteria tab and repeat steps 2 to 6. Alternately, you can copy the configuration from the Critical Criteria tab using the Copy from Critical Criteria option.
  8. Click Next.

You have completed Step 2 in the Create New Health Rule wizard, proceed to Step 3, Configure Health Evaluation Criteria for a Group of Entity Types.

Configure a Condition

  1. In the first field of the condition row, enter a name for the condition.

    The conditions are named A, B, C, and so on by default. You can enter a meaningful name for your reference.

  2. From the dropdown list below the Add Condition button, define metrics to evaluate the condition, and select:
    • a. From the Value dropdown list, select a qualifier for the metric from the following options:

      Qualifier Type

      Description

      Minimum

      The minimum value reported across the configured evaluation time length. Not all metrics have this type.

      Maximum

      The maximum value reported across the configured evaluation time length.  Not all metrics have this type.

      Value

      The arithmetic average of all metric values reported across the configured evaluation time length. This value is based on the type of metric.

      Sum

      The sum of all the metric values reported across the configured evaluation time length.

      b. Click Select a Metric dropdown list. The dropdown lists metrics appropriate to the selected entity types.

      c. If applicable, select a source from the dropdown list.

      or

    • Metric Expression to build a metric expression.
  3. From the Within Baseline dropdown, select the type of comparison to evaluate the metric.

    • To limit the effect of the health rule to conditions during which the metric is within a defined range—standard deviations or percentages—from the baseline, select Within Baseline.
      To limit the effect of the health rule to when the metric is not within that defined range, select Not Within Baseline. Then select the baseline to use, the numeric qualifier of the unit of evaluation, and the unit of evaluation. For example:

      Within Baseline of the All data - Last 15 days by 3 Baseline Standard Deviations
    • To compare the metric with a static literal value, select < Specific value or > Specific Value from the menu, then enter the specific value in the text field. For example:

      Value of Errors per Minute > 100

      To assign the metric with a static literal value, select = Specific value from the menu, then enter the specific value in the text field. For example:

      Disk Pressure = 1
    • To compare the metric with a baseline, select < Baseline or > Baseline from the dropdown list, and then select the baseline to use, the numeric qualifier of the unit of evaluation, and the unit of evaluation. You can use the Baseline Standard Deviation or Baseline Percentage as the unit of evaluation. For example:

      Maximum of Average Response Time is > Baseline of the Daily Trend - Last 30 days by 3 Baseline Standard Deviations

      Baseline Percentages

      The baseline percentage is the percentage above or below the established baseline at which the condition triggers. For example, if you have a baseline value of 850 and you have defined a baseline percentage of > 1%, the condition is true if the value is > [850+(850x0.01)] or 859.  

  1. If you want the condition to evaluate as true whenever a configured metric does not return any data during the evaluation time frame:

    1. Expand Advanced Settings.
    2. Check the Evaluate to true on no data option. 
      This option does not affect the evaluation of unknown in the case where there is no enough data for the rule to evaluate. For example, if the health rule is configured to evaluate the last 30 minutes of data and a new pod is added, the condition evaluates to unknown for the first 30 minutes even if the Evaluate to true on no data box is checked.

  2. If you want to define a Persistence Threshold for the condition to reduce false alerts: 

    1. Select Trigger only when violation occurs __ times in the last __ min(s).

    2. Define the number of times metric performance data should exceed the defined threshold to constitute a violation.

    3. If required, adjust the evaluation time frame by setting an alternate evaluation time frame.

    You can define a persistence threshold for a condition only if you have defined an evaluation time frame of 30 minutes or less.

Build an expression 

To access the expression builder to create a complex expression as the basis of a condition, click Add Expression. The Metric Expression window is displayed that allows you to construct a mathematical expression to use as a metric. 

  1. In the Variable Declarations pane of the Metric Expression builder, click Add variable.
  2. Select a metric from the dropdown list. The dropdown list displays the metrics corresponding to the entity type selected on the Select Entity Type wizard. For example, if you select apm:service as the entity type, the metrics available are Calls Per Minute (calls/min)Average Response Time (ns), and Errors Per Minute (errors/min).
  3. Select a source from the dropdown list. The dropdown list displays the sources appropriate to the selected entity types. For example, if you select apm:service as the entity type, the sources available are sys_derivedinfra-agent, and derived_metric.
  4. Select one of the following qualifiers for the metric from the dropdown list: 

    Qualifier Type

    Description

    Minimum

    The minimum value reported across the configured evaluation time length. This qualifier is not available for all the metrics.

    Maximum

    The maximum value reported across the configured evaluation time length. This qualifier is not available for all the metrics.

    Value

    The arithmetic average of all metric values reported across the configured evaluation time length. This value is based on the type of metric.

    Sum

    The sum of all the metric values reported across the configured evaluation time length.

  5. If you want to add more variables to use in the expression, click Add variable and repeat steps 2 through 4. You can remove a variable by clicking the X icon.
  6. In the Expression pane, build the expression by clicking Insert Variable to insert variables you created along with appropriate mathematical signs.

    A health rule is not evaluated if any metric in the expression has a null value. This is to avoid erroneous evaluations as shown in the following examples:

    Health Rule Evaluation Condition

    A health rule is not evaluated if any metric in the expression has a null value. This is to avoid erroneous evaluations as shown in the following examples:

    ExpressionNull ValueEvaluation
    a-b-c
    a
    entire expression is evaluated negative
    a/b
    b
    the number 'a' is divided by zero, evaluates to an error
    a*b
    a or b
    entire expression is evaluated as zero
  7. When the expression is built, click Submit.

Create a Custom Boolean Expression

Once you define all the conditions required for the health rule, you can create a custom boolean expression to evaluate the health rule.

  1. In the Enter condition combination field, enter a combination of conditions using AND and/or OR operators. For example, (A OR B) AND C.

    This field displays only if you specify Custom expression to evaluate the health rule.

    Health Evaluation Custom Boolean

Delete a Condition

Click to delete a condition component.

If you delete a condition, update the boolean expression accordingly.