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Scaling: Advanced Expressions

The scaling action to be performed can also be defined as a mathematical expression.

If you don't want to use a static value for scaling, you can specify a scaling action parameter using expressions which will be calculated on-the-fly.

Variables​

These variables are allowed:

  • currCapacity – the number of active instances at the time of scaling.
  • value – the value of the metric by which this policy scales (for example, CPUUtilization).

Operators​

These mathematical operations are allowed:

  • Addition: +
  • Subtraction: –
  • Division: /
  • Multiplication: \*
  • Power: ^
  • Square root: SQRT()
  • Conditionals: IF(boolean expression, result if true, result if false)
  • Minimum Value: MIN(v1,v2,v3…)
  • Maximum Value: MAX(v1,v2,v3…)

Examples​

  • currCapacity \* 0.5
  • value \* 2 + 5
  • SQRT(value \* 10)
  • IF(value > 50, currCapacity _ 0.6, currCapacity _ 0.2)
  • MAX(value _ 10, currCapacity _ 3, 5)
  • IF(value > 50 && currCapacity <100, 20, 10)

Fields​

The fields below accept these expressions:

FieldTypeDescription
scaling.up.action.adjustmentStringMathematical expression
scaling.up.action.minTargetCapacityStringMathematical expression
scaling.up.action.targetStringMathematical expression
scaling.up.action.maximumStringMathematical expression
scaling.up.action.minimumStringMathematical expression
scaling.down.action.adjustmentStringMathematical expression
scaling.down.action.maxTargetCapacityStringMathematical expression
scaling.down.action.targetStringMathematical expression
scaling.down.action.maximumStringMathematical expression
scaling.down.action.maximumStringMathematical expression