使用 Docker 优化打包 Rails
依赖环境
ruby: 3.2.1
rails: 7.0.6
node: 18
webpack: 5.4
tailwindcss 3
docker: 23.0.5
目标
通过对打包过程的了解和优化，得到一个体积合适且可用的 Rails 镜像
PS: 想直接看结果的直接跳到最后即可
新建测试项目 myapp
rails new myapp -d postgresql --css tailwind
bundle add webpacker
bundle install
rails webpacker:install
rails tailwindcss:install
rails db:create
rails s
使用 ruby:3.2.1 构建
确保上方执行完成项目可访问
将下方代码复制并放在项目根目录（任意目录都可）的 Dockerfile
FROM ruby:3.2.1
RUN mv /etc/apt/sources.list /etc/apt/sources.list.bak && \
echo "deb https://mirrors.aliyun.com/debian/ bullseye main non-free contrib" >/etc/apt/sources.list && \
echo "deb-src https://mirrors.aliyun.com/debian/ bullseye main non-free contrib" >>/etc/apt/sources.list && \
echo "deb https://mirrors.aliyun.com/debian-security/ bullseye-security main" >>/etc/apt/sources.list && \
echo "deb-src https://mirrors.aliyun.com/debian-security/ bullseye-security main" >>/etc/apt/sources.list && \
echo "deb https://mirrors.aliyun.com/debian/ bullseye-updates main non-free contrib" >>/etc/apt/sources.list && \
echo "deb-src https://mirrors.aliyun.com/debian/ bullseye-updates main non-free contrib" >>/etc/apt/sources.list && \
echo "deb https://mirrors.aliyun.com/debian/ bullseye-backports main non-free contrib" >>/etc/apt/sources.list && \
echo "deb-src https://mirrors.aliyun.com/debian/ bullseye-backports main non-free contrib" >>/etc/apt/sources.list
RUN apt-get update && apt-get install -y \
curl -sL https://deb.nodesource.com/setup_18.x | bash - && \
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - && \
echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list && \
apt-get update && apt-get install -y nodejs yarn postgresql-client net-tools
WORKDIR /app
ENV RAILS_ENV=production
ENV NODE_ENV=production
COPY Gemfile* package.json yarn.lock ./
RUN bundle install --verbose --jobs 20 --retry 5
RUN yarn --ignore-engines
COPY . .
RUN bin/rails assets:precompile
EXPOSE 3000
CMD ["rails", "server", "-b", "0.0.0.0"]
执行打包命令
# 如果 Dockerfile 在根目录
docker build . -t myapp
# 如果 Dockerfile 在其他目录
docker build . -f <Dockerfile Path> -t myapp
我们最终得到的 docker 镜像大小如下：
REPOSITORY TAG SIZE
myapp latest 1.39GB
可以看到还没有任何业务代码的新项目打包都这么大，这是不可接受的，因为是用的 ruby:3.2.1 作为基础镜像的，我们看一下他的镜像大小
docker pull ruby:3.2.1
REPOSITORY TAG SIZE
ruby 3.2.1 844MB
看来我们需要寻找到一个可以替代并且体积更小的镜像，通过 ruby 官方镜像 能看到官方提供了 Alpine 镜像
docker pull ruby:3.2.1-alpine
REPOSITORY TAG SIZE
ruby 3.2.1-alpine 79.9MB
竟然少了 764MB!
使用 ruby:3.2.1-alpine 构建
https://www.alpinelinux.org/
使用 Alpine 镜像作为基础镜像可能有点复杂，需要手动运行一些命令并安装一些依赖包
FROM ruby:3.2.1-alpine
RUN apk update \
&& apk upgrade \
&& apk add --update --no-cache \
build-base curl-dev git libc6-compat postgresql-dev \
yaml-dev zlib-dev nodejs yarn tzdata
WORKDIR /app
ENV RAILS_ENV=production
ENV NODE_ENV=production
COPY Gemfile* package.json yarn.lock ./
RUN bundle install --verbose --jobs 20 --retry 5
RUN yarn --ignore-engines
COPY . .
RUN NODE_OPTIONS=--openssl-legacy-provider RAILS_ENV=production bundle exec rails assets:precompile
EXPOSE 3000
CMD ["rails", "server", "-b", "0.0.0.0"]
执行打包命令，我们得到的镜像大小如下：
REPOSITORY TAG SIZE
myapp-alpine latest 1.16GB
对比 ruby:3.2.1 和 ruby:3.2.1-alpine 的结果看是小了一些，但作为实际生产用仍然太大，我们还可以继续优化 docker 打包流程
REPOSITORY TAG SIZE
myapp-alpine latest 1.16GB
myapp latest 1.39GB
通过多步骤构建 docker 减少构建层数
https://docs.docker.com/build/building/multi-stage/
就像 Git 仓库一样，随着提交/更改的 commits 数量增加项目体积会越来越大，同样 docker 镜像的大小也取决于构建层数，我们可以通过减少 RUN 和 COPY 语句的数量，或者通过类似于
git squash的多步构建来减少层数
# 构建基础包
FROM ruby:3.2.1-alpine AS build-env
ARG RAILS_ROOT=/app
ARG BUILD_PACKAGES="build-base curl-dev git libc6-compat"
ARG DEV_PACKAGES="postgresql-dev yaml-dev zlib-dev nodejs yarn"
ARG RUBY_PACKAGES="tzdata"
ENV RAILS_ENV=production
ENV NODE_ENV=production
ENV BUNDLE_APP_CONFIG="$RAILS_ROOT/.bundle"
WORKDIR $RAILS_ROOT
RUN apk update \
&& apk upgrade \
&& apk add --update --no-cache $BUILD_PACKAGES $DEV_PACKAGES \
$RUBY_PACKAGES
COPY Gemfile* package.json yarn.lock ./
RUN bundle config set --local path vendor/bundle \
&& bundle config set --local without 'development:test:assets' \
&& bundle install -j4 --retry 3
RUN yarn install
COPY . .
RUN NODE_OPTIONS=--openssl-legacy-provider RAILS_ENV=production bundle exec rails assets:precompile
############### 引用构建好的基础包 ###############
FROM ruby:3.2.1-alpine
ARG RAILS_ROOT=/app
ARG PACKAGES="tzdata postgresql-client nodejs bash"
ENV RAILS_ENV=production
ENV BUNDLE_APP_CONFIG="$RAILS_ROOT/.bundle"
WORKDIR $RAILS_ROOT
RUN apk update \
&& apk upgrade \
&& apk add --update --no-cache $PACKAGES
COPY --from=build-env $RAILS_ROOT $RAILS_ROOT
EXPOSE 3000
CMD ["rails", "server", "-b", "0.0.0.0"]
这里打一个新的包作为对比
docker build . -t myapp-alpine-v2
对比与前者打包结果
REPOSITORY TAG SIZE
myapp-alpine-v2 latest 300MB
myapp-alpine latest 1.16GB
myapp latest 1.39GB
是的，相比较少了将近 4 倍，但我们其实还可以再优化
移除不必要的打包文件，即：最终生产使用的 Dockerfile
这里移除的文件都是生产中不需要的，不会影响系统运行的，比如：
node_modulestmp/cachevendor/assetstest- ..
# 构建基础包
FROM ruby:3.2.1-alpine AS build-env
ARG RAILS_ROOT=/app
ARG BUILD_PACKAGES="build-base curl-dev git libc6-compat"
ARG DEV_PACKAGES="postgresql-dev yaml-dev zlib-dev nodejs yarn"
ARG RUBY_PACKAGES="tzdata"
ENV RAILS_ENV=production
ENV NODE_ENV=production
ENV BUNDLE_APP_CONFIG="$RAILS_ROOT/.bundle"
WORKDIR $RAILS_ROOT
RUN apk update \
&& apk upgrade \
&& apk add --update --no-cache $BUILD_PACKAGES $DEV_PACKAGES \
$RUBY_PACKAGES
COPY Gemfile* package.json yarn.lock ./
RUN bundle config set --local path vendor/bundle \
&& bundle config set --local without 'development:test:assets' \
&& bundle install -j4 --retry 3 \
&& rm -rf vendor/bundle/ruby/3.2.0/cache/*.gem \
&& find vendor/bundle/ruby/3.2.0/gems/ -name "*.c" -delete \
&& find vendor/bundle/ruby/3.2.0/gems/ -name "*.o" -delete
RUN yarn install
COPY . .
RUN NODE_OPTIONS=--openssl-legacy-provider RAILS_ENV=production bundle exec rails assets:precompile && \
rm -rf node_modules tmp/cache vendor/assets test
############### 引用构建好的基础包 ###############
FROM ruby:3.2.1-alpine
ARG RAILS_ROOT=/app
ARG PACKAGES="tzdata postgresql-client nodejs bash"
ENV RAILS_ENV=production
ENV BUNDLE_APP_CONFIG="$RAILS_ROOT/.bundle"
WORKDIR $RAILS_ROOT
RUN apk update \
&& apk upgrade \
&& apk add --update --no-cache $PACKAGES
COPY --from=build-env $RAILS_ROOT $RAILS_ROOT
EXPOSE 3000
CMD ["rails", "server", "-b", "0.0.0.0"]
这里打一个新的包作为对比
docker build . -t myapp-alpine-v3
对比与前者打包结果
REPOSITORY TAG SIZE
myapp-alpine-v3 latest 174MB
myapp-alpine-v2 latest 300MB
myapp-alpine latest 1.16GB
myapp latest 1.39GB
最终我们将一个 1.39GB 的镜像缩小到了 174MB