Dockerfile CMD not able to start java -jar

Open Source Projects DockerEngine
1

I am trying to build a image for one Springboot java application using gradle 8.0.2 and java 19jdk imag
e …build is getting successful and I am able to create a image but when I login to container java jar is not running …If I manually trigger java jar application is getting started but its not getting started from the Dockerfile I am using CMD [“java”, “-jar”, “myapp.jar”]

its not getting started when I deploy on Kubernetes using the created image my pod is going in crash loopback as service is not started and getting an error in pod saying Unable to access myapp.jar

I have used ENTRYPOINT as well the container starts application when I use docker run to create a container but that also didn’t work giving same error in Kubernetes POD

I am using user root and have given executable permission to myapp.jar …The jar is available in container

Can someone please suggest

2

Looks like the folder where the java binary is located is not in the PATH.

I assume if the workdir is not set to the path where the jar is located, you should still get a dying container, but you should at least see logs.

3

Below is my dockerfile

Below is my Dockerfile for reference.

FROM gradle:8.0.2-jdk19 AS build

WORKDIR /home/gradle/src

COPY build.gradle settings.gradle gradlew ./

COPY gradle ./gradle

COPY src ./src

RUN ./gradlew build -x test

FROM openjdk:19-alpine

WORKDIR /app

COPY --from=build /home/gradle/src/build/libs/*.jar app.jar

EXPOSE 8080

CMD [“java”, “-jar”, “./app.jar”]

4

Is there a way for us to replicate it?
For example, commands to start containers, k8s manifest, etc.

5

Below is my k8’s manifest
apiVersion: apps/v1
kind: Deployment
metadata:
name: test
namespace: test-dev
spec:
selector:
matchLabels:
app: test
replicas: 1
template:
metadata:
labels:
app: test
spec:
containers:
- name: test
image: myregistry/springboot-api
imagePullPolicy: IfNotPresent
command: [“java”]
args: [“-c”, “-jar”, “app.jar”]
ports:
- containerPort: 8080
protocol: TCP

6

Thank you. However, I could not reproduce it in my environment.
If the pod log is [Error: Unable to access jarfile myapp.jar], I think it is most likely that [/app/myapp.jar] does not exist.
Please check the following two things

  1. Log in to the container container and make sure that /app/myapp.jar exists.
  2. Make sure that the image you are using with Kubernetes is up-to-date
    If you are still unable to do so, re-create the image and run
7

I created a Docker image using above Dockerfile and logged in to the container to check if app.jar is available.

app.jar file is available in Docker container whereas if I use the same image to deploy on Kubernetes and use command as an argument to check the jar and start its giving error as unable to access jar

8

Can you please paste the command you executed and the log you checked?