How to build java spring boot application with kaniko and push it to private registry

Question

New version of kubernetes is without docker so we can not use Jenkins docker in docker with docker plugin:

<plugin>
    <groupId>com.spotify</groupId>
    <artifactId>docker-maven-plugin</artifactId>
    <version>1.2.0</version>
    <configuration>
        <imageName>${docker.image.name}</imageName>
        <imageTags>
            <imageTag>${project.version}</imageTag>
            <imageTag>latest</imageTag>
        </imageTags>
        <dockerDirectory>${basedir}/target/dockerfile</dockerDirectory>
        <resources>
            <resource>
                <targetPath>/</targetPath>
                <directory>${project.build.directory}</directory>
                <include>${project.build.finalName}.jar</include>
            </resource>
        </resources>
    </configuration>
</plugin>

with dockerfile:

FROM openjdk:8-jdk-alpine
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","/app.jar"]

What is the correct way to build image of spring boot application using kaniko ?

I know that kaniko support couple of context but I am not sure what is the best with spring boot application. Using git you still need to build all dependencies and then main application, using local dir/tar you can use same dockerfile but still you need to somehow copy archive to mounted volume in kaniko

I tried this kaniko pod which successfully push image to registry

apiVersion: v1
kind: Pod
metadata:
  name: kaniko
spec:
  containers:
  - name: kaniko
    image: gcr.io/kaniko-project/executor:latest
    args: ["--dockerfile=/Dockerfile",
            "--context=dir:///workspace",
            "--destination=registry/image:version",
            "--skip-tls-verify"] 
    volumeMounts:
      - name: data
        mountPath: /workspace       
  restartPolicy: Never
  volumes:
    - name: data
      hostPath:
        path: /workspace/
        type: Directory

but before this I need to manually copy Dockerfile and jar to mounted volume. Is there some better way how I can use kaniko ?