Dockerfile-example

Use Dockerfile to compile code and build images

These dockerfile may not work well in your project, you need to make some adjustments according to your project

Official documentation for multi-stage builds

Some Tips For Buid Image

1. you can change the software's source to make build-iamge fast

some mirrors site: USTC Mirror Help TUNA Mirror Help Ali Mirror Hel NetEase Mirror Hel Huawei Mirror Help Please use Open Source Mirror Sites reasonably and legally

2. Modify the time znoe in the image to keep the time consistent with yours

method1

RUN ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime

method2

RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories
RUN apk add --no-cache tzdata \
    && ln -snf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime \
    && echo "Asia/Shanghai" > /etc/timezone

3. If you need to execute multiple commands in the image, you can write a startup shell script and execute this script in the startup command of the Dockerfile,remember to give this file an executable permission

RUN chmod -x entrypoint.sh
ENTRYPOINT ["entrypoint.sh"]

4. If you want to add iteams to hosts file, you must write the hosts file at startup

Because the hosts file will be automatically generated when the container is started, the hosts file will be overwritten when the image is built, and the hosts file can be modified when the image is started.

entrypoint.sh

#!/bin/bash
set -x

cat /temp/hosts >> /etc/hosts

cat /etc/hosts

# other commands

5. If you want to reduce docker image size,The following are the methods by which we can achieve docker image optimization

• Using distroless/minimal base images

• Multistage builds

• Minimizing the number of layers

  use

  RUN apt-get update -y && apt-get upgrade -y && apt-get install --no-install-recommends vim net-tools dnsutils -y

  instead of

  RUN apt-get update -y
  RUN apt-get upgrade -y
  RUN apt-get install vim -y
  RUN apt-get install net-tools -y
  RUN apt-get install dnsutils -y

• Understanding caching

  ENV DEBIAN_FRONTEND=noninteractive

• Using Dockerignore

• Keeping application data elsewhere

  It’s highly recommended to use the volume feature of the container runtimes to keep the image separate from the data.

6. Don’t run containers as root, Create a specific user with limited privileges to run your application and make sure that user can run the application. Last, don’t forget to call the newly created user before running the application.

FROM adoptopenjdk/openjdk11:jre
RUN mkdir /app
RUN addgroup --system javauser && adduser -S -s /bin/false -G javauser javauser
COPY /project/target/java-application.jar /app/java-application.jar
WORKDIR /app
RUN chown -R javauser:javauser /app
USER javauser
CMD "java" "-jar" "java-application.jar"