Helm template float arithmetic

Question

$ helm version
version.BuildInfo{Version:"v3.3.0", GitCommit:"8a4aeec08d67a7b84472007529e8097ec3742105", GitTreeState:"dirty", GoVersion:"go1.14.6"}

So I have my template:

  minAvailable: {{ mul .Values.autoscaling.minReplicas 0.75 }}

values.yaml:

autoscaling:
  minReplicas: 3

I would have expected a rendered output of 2.25, but I get 0 (3 * 0 because 0.75 gets floored...)

I've tried things like

  minAvailable: {{ mul (float .Values.autoscaling.minReplicas) 0.75 }}

Ultimately I'm going to floor the value to get back to an int...

  minAvailable: {{ floor ( mul .Values.autoscaling.minReplicas 0.75 ) }}

But I just don't understand why I can't seem to do simple float arithmetic

---

Other things I've tried

  minAvailable: {{ float64 .Values.autoscaling.minReplicas }} 

  minAvailable: {{ float64 .Values.autoscaling.minReplicas | toString }} 

nothing produces a float number....

I've even tried doing this in values.yaml

autoscaling:
  minReplicas: 3.0

Answer 1

Pod Disruption Budgets actually take percentages...

so can do

  minAvailable: "66%" # 2/3

or

  minAvailable: "75%" # 3/4

From the docs:

if you have 7 Pods and you set minAvailable to "50%", it's not immediately obvious whether that means 3 Pods or 4 Pods must be available. Kubernetes rounds up to the nearest integer, so in this case, 4 Pods must be available.

So essentially, 66% of 3 is 1.98 so will be rounded up to 2