Alpine镜像
一、简介
Alpine 操作系统是一个面向安全的轻型 Linux 发行版。它不同于通常 Linux 发行版，Alpine 采用了 musl libc 和 busybox 以减小系统的体积和运行时资源消耗，但功能上比 busybox 又完善的多，因此得到开源社区越来越多的青睐。在保持瘦身的同时，Alpine 还提供了自己的包管理工具 apk，可以通过 https://pkgs.alpinelinux.org/packages 网站上查询包信息，也可以直接通过 apk 命令直接查询和安装各种软件。
Alpine 由非商业组织维护的，支持广泛场景的 Linux发行版，它特别为资深/重度Linux用户而优化，关注安全，性能和资源效能。Alpine 镜像可以适用于更多常用场景，并且是一个优秀的可以适用于生产的基础系统/环境。
Alpine Docker 镜像也继承了 Alpine Linux 发行版的这些优势。相比于其他 Docker 镜像，它的容量非常小，仅仅只有 5 MB 左右（对比 Ubuntu 系列镜像接近 200 MB），且拥有非常友好的包管理机制。官方镜像来自 docker-alpine 项目。
目前 Docker 官方已开始推荐使用 Alpine 替代之前的 Ubuntu 做为基础镜像环境。这样会带来多个好处。包括镜像下载速度加快，镜像安全性提高，主机之间的切换更方便，占用更少磁盘空间等。
Github：https://github.com/alpinelinux/docker-alpine
Dockerhub：https://hub.docker.com/_/alpine
二、APK包管理器
可在包管理中心查看支持的包：https://pkgs.alpinelinux.org/packages
1、apk命令详解
命令格式
apk 子命令 参数项
全局参数项
-h, --help Show generic help or applet specific help
-p, --root DIR Install packages to DIR
-X, --repository REPO Use packages from REPO
-q, --quiet Print less information
-v, --verbose Print more information (can be doubled)
-i, --interactive Ask confirmation for certain operations
-V, --version Print program version and exit
-f, --force Enable selected --force-* (deprecated)
--force-binary-stdout Continue even if binary data is to be output
--force-broken-world Continue even if 'world' cannot be satisfied
--force-non-repository Continue even if packages may be lost on reboot
--force-old-apk Continue even if packages use unsupported features
--force-overwrite Overwrite files in other packages
--force-refresh Do not use cached files (local or from proxy)
-U, --update-cache Alias for --cache-max-age 1
--progress Show a progress bar
--progress-fd FD Write progress to fd
--no-progress Disable progress bar even for TTYs
--purge Delete also modified configuration files (pkg removal) and uninstalled packages from cache (cache clean)
--allow-untrusted Install packages with untrusted signature or no signature
--wait TIME Wait for TIME seconds to get an exclusive repository lock before failing
--keys-dir KEYSDIR Override directory of trusted keys
--repositories-file REPOFILE Override repositories file
--no-network Do not use network (cache is still used)
--no-cache Do not use any local cache path
--cache-dir CACHEDIR Override cache directory
--cache-max-age AGE Maximum AGE (in minutes) for index in cache before refresh
--arch ARCH Use architecture with --root
--print-arch Print default arch and exit
commit参数项
-s, --simulate Show what would be done without actually doing it
--clean-protected Do not create .apk-new files in configuration dirs
--overlay-from-stdin Read list of overlay files from stdin
--no-scripts Do not execute any scripts
--no-commit-hooks Skip pre/post hook scripts (but not other scripts)
--initramfs-diskless-boot Enables options for diskless initramfs boot (e.g. skip hooks)
子命令
①安装与删除
add：安装包
--initdb Initialize database -u, --upgrade Prefer to upgrade package -l, --latest Select latest version of package (if it is not pinned), and print error if it cannot be installed due to other dependencies -t, --virtual NAME Instead of adding all the packages to 'world', create a new virtual package with the listed dependencies and add that to 'world'; the actions of the command are easily reverted by deleting the virtual packagedel：卸载并删除包
-r, --rdepends Recursively delete all top-level reverse dependencies too
②包的元信息管理
fix：在不改动主要的依赖的情况下进行包的修复或者升级
-d, --depends Fix all dependencies too -r, --reinstall Reinstall the package (default) -u, --upgrade Prefer to upgrade package -x, --xattr Fix packages with broken xattrs --directory-permissions Reset all directory permissionsupdate：从远程仓库获取信息更新本地仓库索引
upgrade：令升级系统已安装的所以软件包（一般包括内核），当然也可指定仅升级部分软件包（通过-u或–upgrade选择指定
-a, --available Resets versioned world dependencies, and changes to prefer replacing or downgrading packages (instead of holding them) if the currently installed package is no longer available from any repository -l, --latest Select latest version of package (if it is not pinned), and print error if it cannot be installed due to other dependencies --no-self-upgrade Do not do early upgrade of 'apk-tools' package --self-upgrade-only Only do self-upgradecache：对缓存进行操作，比如对缺失的包进行缓存或者对于不需要的包进行缓存删除
-u, --upgrade Prefer to upgrade package -l, --latest Select latest version of package (if it is not pinned), and print error if it cannot be installed due to other dependencies
③查询搜索包
info：列出所有已安装的软件包
-L, --contents List contents of the PACKAGE -e, --installed Check if PACKAGE is installed -W, --who-owns Print the package owning the specified file -R, --depends List packages that the PACKAGE depends on -P, --provides List virtual packages provided by PACKAGE -r, --rdepends List all packages depending on PACKAGE --replaces List packages whom files PACKAGE might replace -i, --install-if List the PACKAGE's install_if rule -I, --rinstall-if List all packages having install_if referencing PACKAGE -w, --webpage Show URL for more information about PACKAGE -s, --size Show installed size of PACKAGE -d, --description Print description for PACKAGE --license Print license for PACKAGE -t, --triggers Print active triggers of PACKAGE -a, --all Print all information about PACKAGElist：按照指定条件进行包的列表信息显示
-I, --installed List installed packages only -O, --orphaned List orphaned packages only -a, --available List available packages only -u, --upgradable List upgradable packages only -o, --origin List packages by origin -d, --depends List packages by dependency -P, --providers List packages by providersearch：查询相关的包的详细信息，支持正则
-a, --all Show all package versions (instead of latest only) -d, --description Search package descriptions (implies -a) -x, --exact Require exact match (instead of substring match) -e Synonym for -x (deprecated) -o, --origin Print origin package name instead of the subpackage -r, --rdepends Print reverse dependencies of package --has-origin List packages that have the given origin
dot：生成依赖之间的关联关系图（使用箭头描述）
--errors Output only parts of the graph which are considered erroneous: e.g. cycles and missing packages --installed Consider only installed packagespolicy：显示包的仓库策略信息
④源管理
stats：显示仓库和包的安装相关的统计信息
index：使用文件生成仓库索引文件
-o, --output FILE Write the generated index to FILE -x, --index INDEX Read INDEX to speed up new index creation by reusing the information from an old index -d, --description TEXT Embed TEXT as description and version information of the repository index --rewrite-arch ARCH Use ARCH as architecture for all packagesfetch：从全局仓库下载包到本地目录
-L, --link Create hard links if possible -R, --recursive Fetch the PACKAGE and all its dependencies --simulate Show what would be done without actually doing it -s, --stdout Dump the .apk to stdout (incompatible with -o, -R, --progress) -o, --output DIR Directory to place the PACKAGEs toverify：验证包的完整性和签名信息
manifest：显示package各组成部分的checksum
2、操作
①安装软件
FROM alpine:3.11.5
RUN sed -i "s/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g" /etc/apk/repositories \
&& apk add --no-cache git
②替换Alpine的软件源
常见国内Alpine软件源：
阿里云
FROM alpilne:3.11.5 RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories中科大
FROM alpilne:3.11.5 RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.ustc.edu.cn/g' /etc/apk/repositories
③安装bash
FROM alpine:3.11.5
RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories \
&& apk add --no-cache bash bash-doc bash-completion
④安装telnet
FROM alpine:3.11.5
RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories \
&& apk add --no-cache busybox-extras
⑤安装Docker Client和Make
FROM alpine:3.11.5
RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories \
&& apk add --no-cache docker-cli make
⑥修改用户的所属用户组
FROM alpine:3.11.5
RUN sed -i 's/1001/0/g' /etc/passwd
⑦设置系统语言为“en_US.UTF-8”，以防中文乱码
FROM alpine:3.11.5
ENV LANG=en_US.UTF-8 \
LANGUAGE=en_US.UTF-8
RUN apk --no-cache add ca-certificates \
&& wget -q -O /etc/apk/keys/sgerrand.rsa.pub https://alpine-pkgs.sgerrand.com/sgerrand.rsa.pub \
&& wget -q https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.29-r0/glibc-2.29-r0.apk \
&& wget -q https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.29-r0/glibc-bin-2.29-r0.apk \
&& wget -q https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.29-r0/glibc-i18n-2.29-r0.apk \
&& apk add glibc-2.29-r0.apk glibc-bin-2.29-r0.apk glibc-i18n-2.29-r0.apk \
&& rm -rf /usr/lib/jvm glibc-2.29-r0.apk glibc-bin-2.29-r0.apk glibc-i18n-2.29-r0.apk \
&& /usr/glibc-compat/bin/localedef --force --inputfile POSIX --charmap UTF-8 "$LANG" || true \
&& echo "export LANG=$LANG" > /etc/profile.d/locale.sh \
&& apk del glibc-i18n
参考：
- https://github.com/gliderlabs/docker-alpine/issues/144
- https://gist.github.com/alextanhongpin/aa55c082a47b9a1b0060a12d85ae7923
⑧设置时区
FROM alpine:3.11.5
ENV TZ=Asia/Shanghai
RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories \
&& apk add --no-cache tzdata \
&& cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime \
&& echo "Asia/Shanghai" > /etc/timezone