New functionality

[jarlva]

I have two requests/questions regarding the helm chart:

1. Can we define an external HPA metric? Currently, there is only an option for mem/cpu.
2. Can we declare a percentage max Java memory commitment instead of an absolute number? Meaning, replace the -Xmx46G with -XX:MaxRAMPercentage=75.0. This is very useful when changing the VM size to a different memory size. Java will automatically adjust based on the available total memory. Without having to change Xmx.

[luiscosta18]

Hello @jarlva ,

1.

Tipycally, HorizontalPodAutoscaler templates are created based on cpu/memory metrics, as it is defined in the chart -https://github.com/trinodb/charts/blob/main/charts/trino/templates/autoscaler.yaml

HPA can also be defined using any other custom metric you specify - https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/

Also, for trino helm chart you can use keda-scaledobject, if you want to scale the workers based on prometheus triggers:

https://medium.com/bestsecret-tech/maximize-performance-the-bestsecret-to-scaling-trino-clusters-with-keda-c209efe4a081
https://keda.sh/docs/2.17/scalers/prometheus

You can use the sidecar jmx-exporter, to retrived trino metrics in prometheus format. Another alternative, is to use jmx_prometheus_javaagent:
https://stackoverflow.com/questions/73383533/using-jmx-exporter-as-javaagent-for-a-sample-java-application
https://repo1.maven.org/maven2/io/prometheus/jmx/jmx_prometheus_javaagent/1.0.1/
https://github.com/trinodb/charts/blob/main/charts/trino/templates/configmap-worker.yaml#L45 (but in this case, it would run as another process inside the worker container and you need to mount the configMap with config.yaml)

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2.

You can define extra jvm properties:
https://github.com/trinodb/charts/blob/main/charts/trino/templates/configmap-worker.yaml#L45
https://github.com/trinodb/charts/blob/main/charts/trino/values.yaml#L813

[kornypoet]

I think that setting -Xmx will take precedence over -XX:MaxRAMPercentage if both are specified, meaning adding the latter as another JVM property won't have the desired effect.