DevOps Classroom notes 09/Sep/2026

Docker ENV

• Sets an environment variable inside the image. Available at both build time (later steps) and run time (inside the running container), and can be overridden at docker run.

ENV key=value
ENV project=devOps
ENV APP_ENV=Prod
ENV JAVA_HOME=/user/jvm/openjdk-17-jdk/

ENV expose_port=8080

RUN echo "$JAVA_HOME"

EXPOSE $expose_port

FROM ubuntu:latest

ENV JAVA_VERSION=17 \
    MAVEN_VERSION=3.8.6 \
    BRANCH=main \
    JARFILE=spring-petclinic-2.7.0.jar

ENV dbhost="" \
    dbpassword=""

# Install dependencies in one layer
RUN apt-get update && \
    apt-get install -y openjdk-${JAVA_VERSION}-jdk maven git && \
    rm -rf /var/lib/apt/lists/*

# Clone repo (shallow clone for efficiency)
RUN git clone --depth 1 -b ${BRANCH} https://github.com/spring-projects/spring-petclinic.git

WORKDIR spring-petclinic

# Build and copy jar
RUN mvn clean package -DskipTests

RUN echo "curret path is $(pwd)"

WORKDIR /app

RUN cp -rf ../spring-petclinic/target/*.jar ${JARFILE}
# Cleanup source
RUN rm -rf ../spring-petclinic

# Use shell form CMD so env vars expand
CMD java -jar /app/${JARFILE}

override env at run time

docker run -dit -e JARFILE=spring-petclinic-2.7.0.jar –name demo-spring image:tag

Task

1. try to install nopcommerce appliction in linux machine follow below steps Click here get steps to install nopcommerce