Maven docker 缓存依赖项 [英] Maven docker cache dependencies
问题描述
我正在尝试使用 docker 来自动化 maven 构建.我要构建的项目需要将近20分钟才能下载所有依赖项，因此我尝试构建一个可以缓存这些依赖项的docker镜像，但似乎并没有保存它.我的 Dockerfile 是
I'm trying to use docker to automate maven builds. The project I want to build takes nearly 20 minutes to download all the dependencies, so I tried to build a docker image that would cache these dependencies, but it doesn't seem to save it. My Dockerfile is
FROM maven:alpine
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
ADD pom.xml /usr/src/app
RUN mvn dependency:go-offline
图像构建完成，并且确实下载了所有内容.但是，生成的图像与基本 maven:alpine 图像的大小相同，因此它似乎没有缓存图像中的依赖项.当我尝试使用该图像mvn compile 时，它经历了整整 20 分钟的重新下载所有内容.
The image builds, and it does download everything. However, the resulting image is the same size as the base maven:alpine image, so it doesn't seem to have cached the dependencies in the image. When I try to use the image to mvn compile it goes through the full 20 minutes of redownloading everything.
是否可以构建一个缓存我的依赖项的 Maven 镜像，这样它们就不必在我每次使用该镜像执行构建时都下载?
Is it possible to build a maven image that caches my dependencies so they don't have to download everytime I use the image to perform a build?
我正在运行以下命令:
docker build -t my-maven .
docker run -it --rm --name my-maven-project -v "$PWD":/usr/src/mymaven -w /usr/src/mymaven my-maven mvn compile
我的理解是，在 docker 构建过程中 RUN 所做的任何事情都会成为结果映像的一部分.
My understanding is that whatever RUN does during the docker build process becomes part of the resulting image.
推荐答案
通常，pom.xml 文件中没有变化，但是当您尝试启动 docker 镜像时，只有一些其他源代码发生了变化建造.在这种情况下，您可以这样做:
Usually, there's no change in pom.xml file but just some other source code changes when you're attempting to start docker image build. In such circumstance you can do this:
仅供参考:
FROM maven:3-jdk-8
ENV HOME=/home/usr/app
RUN mkdir -p $HOME
WORKDIR $HOME
# 1. add pom.xml only here
ADD pom.xml $HOME
# 2. start downloading dependencies
RUN ["/usr/local/bin/mvn-entrypoint.sh", "mvn", "verify", "clean", "--fail-never"]
# 3. add all source code and start compiling
ADD . $HOME
RUN ["mvn", "package"]
EXPOSE 8005
CMD ["java", "-jar", "./target/dist.jar"]
所以关键是:
添加
pom.xml文件.
然后mvn verify --fail-never它，它会下载maven依赖.
then mvn verify --fail-never it, it will download maven dependencies.
然后添加所有源文件，然后开始编译(mvn package).
add all your source file then, and start your compilation(mvn package).
当你的 pom.xml 文件有变化或者你是第一次运行这个脚本时，docker 会做 1 -> 2 -> 3. 当没有变化时在pom.xml文件中，docker会跳过第1、2步，直接做3.
When there are changes in your pom.xml file or you are running this script for the first time, docker will do 1 -> 2 -> 3. When there are no changes in pom.xml file, docker will skip step 1、2 and do 3 directly.
这个简单的技巧可以用于许多其他的包管理环境(gradle、yarn、npm、pip).
This simple trick can be used in many other package management circumstances(gradle、yarn、npm、pip).
您还应该考虑使用 mvn dependency:resolve 或 mvn dependency:go-offline 作为其他注释 &答案提示.
You should also consider using mvn dependency:resolve or mvn dependency:go-offline accordingly as other comments & answers suggest.
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