如何使用缓存快速重建 dockerfile? [英] How to rebuild dockerfile quick by using cache?

问题描述

我想优化我的 Dockerfile.我希望将缓存文件保存在磁盘中.但是，我发现当我运行 docker build . 它总是尝试从网络获取每个文件.

I want to optimize my Dockerfile. And I wish to keep cache file in disk. But, I found when I run docker build . It always try to get every file from network.

我希望在构建期间共享我的缓存目录(例如/var/cache/yum/x86_64/6).但是，它只适用于 docker run -v ....

I wish to share My cached directory during build (eg. /var/cache/yum/x86_64/6). But, it works only on docker run -v ....

有什么建议吗?(在这个例子中，只安装了 1 个 rpm，在实际情况下，我需要安装数百个 rpm)

Any suggestion?(In this example, only 1 rpm installed, in real case, I require to install hundreds rpms)

我的 Dockerfile 草案

My draft Dockerfile

FROM centos:6.4
RUN yum update -y
RUN yum install -y openssh-server
RUN sed -i -e 's:keepcache=0:keepcache=1:' /etc/yum.conf
VOLUME ["/var/cache/yum/x86_64/6"] 
EXPOSE 22

第二次，我想构建一个类似的图像

At second time, I want to build a similar image

FROM centos:6.4
RUN yum update -y
RUN yum install -y openssh-server vim

我不希望再次从 internat 获取 openssh-server(它很慢).在我的实际情况下，它不是一个包，大约是 100 个包.

I don't want the fetch openssh-server from internat again(It is slow). In my real case, it is not one package, it is about 100 packages.

推荐答案

更新以前的答案，当前 docker 构建接受 --build-arg 传递环境变量，如 http_proxy而不将其保存在结果图像中.

An update to previous answers, current docker build accepts --build-arg that pass environment variables like http_proxy without saving it in the resulting image.

例子:

# get squid
docker run --name squid -d --restart=always 
  --publish 3128:3128 
  --volume /var/spool/squid3 
  sameersbn/squid:3.3.8-11

# optionally in another terminal run tail on logs
docker exec -it squid tail -f /var/log/squid3/access.log

# get squid ip to use in docker build
SQUID_IP=$(docker inspect --format '{{ .NetworkSettings.IPAddress }}' squid)

# build your instance
docker build --build-arg http_proxy=http://$SQUID_IP:3128 .

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