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javadockerkubernetesdockerfilekubernetes-pod
Ritesh Singh
Ritesh Singh

Reputation: 223

How to set Heap Size in docker file for application running inside docker container deployed on kubernetes pod?

I have a docker file which looks something like this:

FROM openjdk:11

ADD target/test-1.0-SNAPSHOT.jar app.jar

ENTRYPOINT ["java", "-jar", "/app.jar"]

My application is containerised and running inside a K8s pod. Now I read and understand that max heap size always takes 25% of the total pod memory. (for example, if pod resource is 2048Mi then 512 MB is your heap size allocated) I do not want this default behaviour of memory allocation rather I want a custom size to specify for my heap memory. Can anyone please tell me how to do that? I have tried passing the "-Xms" and "-Xmx" parameters as shown below in my docker file but it does not work?

ENTRYPOINT ["java","-Xms128M","-Xmx256M","-jar", "/app.jar"]

Upvotes: 0

Views: 2658

Answers (1)

Gurkan İlleez
Gurkan İlleez

Reputation: 1573

apiVersion: v1
kind: Pod
metadata:
  name: envar-demo
  labels:
    purpose: demonstrate-envars
spec:
  containers:
  - name: envar-demo-container
    image: gcr.io/google-samples/node-hello:1.0
    env:
    - name: DEMO_GREETING
      value: "Hello from the environment"
    - name: DEMO_FAREWELL
      value: "Such a sweet sorrow"
    - name: JAVA_ARGS
      value: "-Xmx1024M -Xms512M \"

You can simply pass JAVA_ARGS to deployment yaml and you can limit usage of heap. The example is taken from kubernetes official page so it is node image but you can simply add JAVA_ARGS to environment variables.

Reference : https://kubernetes.io/docs/tasks/inject-data-application/define-environment-variable-container/

Upvotes: 2

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