Deploying a Dockerfile and Jar file into OpenShift 4

Lets say i have a spring boot Jar file, and i want to run it in directly. We can run it by using below command.

$ java -jar existing-app.jar

But somewhere in the future i want to containerized them so that we can run it anywhere have to worry about infrastructure dependencies. For that purpose I need to have a Dockerfile, copy, and run my jar file inside it.

FROM openjdk:11.0.7-jre-slim-buster

LABEL base-image="openjdk:11.0.7-jre-slim-buster" \
      java-version="11.0.7" \
      purpose="Hello World with Java and Dockerfile"

MAINTAINER Muhammad Edwin < edwin at redhat dot com >

# set working directory at /deployments
WORKDIR /deployments

# copy my jar file
COPY existing-app.jar app.jar

# gives uid
USER 185

EXPOSE 8080

# run it
CMD ["java", "-jar","app.jar"]

I can build the container by running below command,

$ docker build -t hello-world-snowdrop .

And run it.

$ docker run -p 8080:8080 hello-world-snowdrop

In order to have above commands runs well, we need to have below structure in our folder.

$ tree
.
+--- Dockerfile
+--- existing-app.jar

The same concept we can use when we want to deploy our app into Openshift. The only difference is the docker build process is being done in Openshift.

$ oc new-build --strategy docker --binary \ 
		--docker-image openjdk:11.0.7-jre-slim-buster \
		--name hello-world-snowdrop
		
$ oc start-build hello-world-snowdrop \ 
		--from-dir . --follow

And below are the commands we can use for deploy, run and expose our app into Openshift.

$ oc new-app hello-world-snowdrop

$ oc create route edge --service hello-world-snowdrop

Dont forget to run above command within the same folder with our Dockerfile and jar files.
Hope it helps, and dont forget to have fun with Openshift 4.