alpine 介紹

Alpine 操作系統是一個面向安全的輕型 Linux 發行版。它不同于通常 Linux 發行版，Alpine 采用了 musl libc 和 busybox 以減小系統的體積和運行時資源消耗，但功能上比 busybox 又完善的多，因此得到開源社區越來越多的青睞。在保持瘦身的同時，Alpine 還提供了自己的包管理工具 apk，可以通過 https://pkgs.alpinelinux.org/packages 網站上查詢包信息，也可以直接通過 apk 命令直接查詢和安裝各種軟件。

Alpine 由非商業組織維護的，支持廣泛場景的 Linux發行版，它特別為資深/重度Linux用戶而優化，關注安全，性能和資源效能。Alpine 鏡像可以適用于更多常用場景，并且是一個優秀的可以適用于生產的基礎系統/環境。

Alpine Docker 鏡像也繼承了 Alpine Linux 發行版的這些優勢。相比于其他 Docker 鏡像，它的容量非常小，僅僅只有 5 MB 左右（對比 Ubuntu 系列鏡像接近 200 MB），且擁有非常友好的包管理機制。官方鏡像來自 docker-alpine 項目。

目前 Docker 官方已開始推薦使用 Alpine 替代之前的 Ubuntu 做為基礎鏡像環境。這樣會帶來多個好處。包括鏡像下載速度加快，鏡像安全性提高，主機之間的切換更方便，占用更少磁盤空間等。

下表是官方鏡像的大小比較：

REPOSITORY          TAG           IMAGE ID          VIRTUAL SIZE
alpine              latest        4e38e38c8ce0      4.799 MB
debian              latest        4d6ce913b130      84.98 MB
ubuntu              latest        b39b81afc8ca      188.3 MB
centos              latest        8efe422e6104      210 MB

–Alpine 官網：https://www.alpinelinux.org/
–Alpine 官方倉庫：https://github.com/alpinelinux
–MARKDOWN_HASH45a94c5ae2df00c49cca09d7d26c06ecMARKDOWNHASH 官方鏡像：https://hub.docker.com//alpine/
–Alpine 官方鏡像倉庫：https://github.com/gliderlabs/docker-alpine
–Alpine 阿里云的鏡像倉庫：https://mirrors.aliyun.com/alpine/

范例：alpine安裝軟件

#修改源替換成阿里源，將里面 dl-cdn.alpinelinux.org 的 改成 mirrors.aliyun.com
vi etc/apk/repositories
http://mirrors.aliyun.com/alpine/v3.8/main/
http://mirrors.aliyun.com/alpine/v3.8/community/

#更新源
apk update

#安裝軟件
apk add vim

#刪除軟件
apk del openssh openntp vim

范例：

/ # apk --help
apk-tools 2.10.4, compiled for x86_64.

Installing and removing packages:
  add       Add PACKAGEs to 'world' and install (or upgrade) them, while ensuring that all dependencies are met
  del       Remove PACKAGEs from 'world' and uninstall them

System maintenance:
  fix       Repair package or upgrade it without modifying main dependencies
  update    Update repository indexes from all remote repositories
  upgrade   Upgrade currently installed packages to match repositories
  cache     Download missing PACKAGEs to cache and/or delete unneeded files from cache

Querying information about packages:
  info      Give detailed information about PACKAGEs or repositories
  list      List packages by PATTERN and other criteria
  dot       Generate graphviz graphs
  policy    Show repository policy for packages

Repository maintenance:
  index     Create repository index file from FILEs
  fetch     Download PACKAGEs from global repositories to a local directory
  verify    Verify package integrity and signature
  manifest  Show checksums of package contents

Use apk <command> --help for command-specific help.
Use apk --help --verbose for a full command listing.

This apk has coffee making abilities.

/ # apk add  nginx
/ # apk info nginx
nginx-1.16.1-r6 description:
HTTP and reverse proxy server (stable version)

nginx-1.16.1-r6 webpage:
https://www.nginx.org/

nginx-1.16.1-r6 installed size:
1126400

~ # apk manifest nginx
sha1:d21a96358a10b731f8847e6d32799efdc2a7f421  etc/logrotate.d/nginx
sha1:50bd6d3b4f3e6b577d852f12cd6939719d2c2db5  etc/init.d/nginx
sha1:379c1e2a2a5ffb8c91a07328d4c9be2bc58799fd  etc/nginx/scgi_params
sha1:da38e2a0dded838afbe0eade6cb837ac30fd8046  etc/nginx/fastcgi_params
sha1:cc2fcdb4605dcac23d59f667889ccbdfdc6e3668  etc/nginx/uwsgi_params
sha1:cbf596ddb3433a8e0d325f3c188bec9c1bb746b3  etc/nginx/fastcgi.conf
sha1:e39dbc36680b717ec902fadc805a302f1cf62245  etc/nginx/mime.types
sha1:e9dddf20f1196bb67eef28107438b60c4060f4d3  etc/nginx/nginx.conf
sha1:7b2a4da1a14166442c10cbf9e357fa9fb53542ca  etc/nginx/conf.d/default.conf
sha1:cd7f5dc8ccdc838a2d0107511c90adfe318a81e7  etc/conf.d/nginx
sha1:05f050f6ed86c5e6b48c2d2328e81583315431be  usr/sbin/nginx
sha1:c3f02ca81f7f2c6bde3f878b3176f225c7781c7d  var/lib/nginx/modules
sha1:0510312d465b86769136983657df98c1854f0b60  var/lib/nginx/run
sha1:35db17c18ce0b9f84a3cc113c8a9e94e19f632b1  var/lib/nginx/logs
sha1:7dd71afcfb14e105e80b0c0d7fce370a28a41f0a  var/lib/nginx/html/index.html
sha1:95de71d58b37f9f74bede0e91bc381d6059fc2d7  var/lib/nginx/html/50x.html
~ # ls -l /bin
total 824
lrwxrwxrwx    1 root     root            12 Jan 16 21:52 arch -> /bin/busybox
lrwxrwxrwx    1 root     root            12 Jan 16 21:52 ash -> /bin/busybox
lrwxrwxrwx    1 root     root            12 Jan 16 21:52 base64 -> /bin/busybox
lrwxrwxrwx    1 root     root            12 Jan 16 21:52 bbconfig -> /bin/busybox
-rwxr-xr-x    1 root     root        841288 Jan 15 10:36 busybox
lrwxrwxrwx    1 root     root            12 Jan 16 21:52 cat -> /bin/busybox
lrwxrwxrwx    1 root     root            12 Jan 16 21:52 chgrp -> /bin/busybox
lrwxrwxrwx    1 root     root            12 Jan 16 21:52 chmod -> /bin/busybox
lrwxrwxrwx    1 root     root            12 Jan 16 21:52 chown -> /bin/busybox

下載鏡像

從docker 倉庫將鏡像下載到本地，命令格式如下：

docker pull  倉庫服務器:端口/項目名稱/鏡像名稱:tag(版本)號

鏡像下載保存的路徑：

/var/lib/docker/overlay2/鏡像ID

注意：鏡像下載完成后，會自動解壓縮，比官網顯示的可能會大很多，如： centos8.1.1911下載時只有70MB，下載完后顯示237MB

范例：從docker官網下載鏡像

docker pull hello-world
docker pull alpine
docker pull busybox
docker pull nginx    
docker pull centos
docker pull centos:centos7.7.1908
docker pull docker.io/library/mysql:5.7.29
docker pull mysql:5.6.47

范例：下載鏡像alpine

[root@ubuntu1804 ~]#ls /var/lib/docker/overlay2/
l
[root@ubuntu1804 ~]#du -sh /var/lib/docker/overlay2
8.0K    /var/lib/docker/overlay2
[root@ubuntu1804 ~]#ls /var/lib/docker/overlay2/l
[root@ubuntu1804 ~]#docker pull hello-world
Using default tag: latest
latest: Pulling from library/hello-world
1b930d010525: Pull complete 
Digest: sha256:9572f7cdcee8591948c2963463447a53466950b3fc15a247fcad1917ca215a2f
Status: Downloaded newer image for hello-world:latest
docker.io/library/hello-world:latest
[root@ubuntu1804 ~]#docker pull alpine:3.11.3
3.11.3: Pulling from library/alpine
c9b1b535fdd9: Pull complete 
Digest: sha256:ab00606a42621fb68f2ed6ad3c88be54397f981a7b70a79db3d1172b11c4367d
Status: Downloaded newer image for alpine:3.11.3
docker.io/library/alpine:3.11.3
[root@ubuntu1804 ~]#docker pull busybox
Using default tag: latest
latest: Pulling from library/busybox
bdbbaa22dec6: Pull complete 
Digest: sha256:6915be4043561d64e0ab0f8f098dc2ac48e077fe23f488ac24b665166898115a
Status: Downloaded newer image for busybox:latest
docker.io/library/busybox:latest
[root@ubuntu1804 ~]#docker pull centos:centos8.1.1911
centos8.1.1911: Pulling from library/centos
8a29a15cefae: Pull complete 
Digest: sha256:fe8d824220415eed5477b63addf40fb06c3b049404242b31982106ac204f6700
Status: Downloaded newer image for centos:centos8.1.1911
docker.io/library/centos:centos8.1.1911
[root@ubuntu1804 ~]#du -sh /var/lib/docker/overlay2/*
5.9M    /var/lib/docker/overlay2/1802616f4c8e0a0b52c839431b6faa8ac21f4bd831548dcbd46943d3f60061fa
16K /var/lib/docker/overlay2/5773b92e1351da5e589d0573d9f22d1ec3be1e0e98edbfcddba4b830f12c7be2
1.3M    /var/lib/docker/overlay2/de31641b8d2207de7f08eabb5240474a1aaccfef08b6034dcee02b9623f8d9dc
252M    /var/lib/docker/overlay2/f41df336075611f9e358e5eaf2ebd5089920a90ba68760cdec8da03edff362f7
20K /var/lib/docker/overlay2/l
[root@ubuntu1804 ~]#docker images 
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
alpine              3.11.3              e7d92cdc71fe        7 days ago          5.59MB
centos              centos8.1.1911      470671670cac        7 days ago          237MB
busybox             latest              6d5fcfe5ff17        4 weeks ago         1.22MB
hello-world         latest              fce289e99eb9        12 months ago       1.84kB

[root@ubuntu1804 ~]#ls -l  /var/lib/docker/overlay2/l
total 16
lrwxrwxrwx 1 root root 72 Jan 25 19:51 C5ZTDYHYDTO7BQG6HX36MU6X5K -> ../de31641b8d2207de7f08eabb5240474a1aaccfef08b6034dcee02b9623f8d9dc/diff
lrwxrwxrwx 1 root root 72 Jan 25 19:57 DEXHVNUGFLFJCSJAKISOHQG7JY -> ../f41df336075611f9e358e5eaf2ebd5089920a90ba68760cdec8da03edff362f7/diff
lrwxrwxrwx 1 root root 72 Jan 25 19:51 KJ5IA5AUHFUEQXFKJA7UDUIA7A -> ../1802616f4c8e0a0b52c839431b6faa8ac21f4bd831548dcbd46943d3f60061fa/diff
lrwxrwxrwx 1 root root 72 Jan 25 19:51 ZM3U4WDNHGJJX5DXHA5M4ZWAIW -> ../5773b92e1351da5e589d0573d9f22d1ec3be1e0e98edbfcddba4b830f12c7be2/diff

范例：

[root@ubuntu1804 ~]#docker pull docker.io/library/mysql:5.7.29
5.7.29: Pulling from library/mysql
804555ee0376: Pull complete 
c53bab458734: Pull complete 
ca9d72777f90: Pull complete 
2d7aad6cb96e: Pull complete 
8d6ca35c7908: Pull complete 
6ddae009e760: Pull complete 
327ae67bbe7b: Pull complete 
9e05241b7707: Pull complete 
e822978df8f0: Pull complete 
14ca71ed53be: Pull complete 
026afe6fd35e: Pull complete 
Digest: sha256:2ca675966612f34b4036bbcfa68cb049c03e34b561fba0f88954b03931823d29
Status: Downloaded newer image for mysql:5.7.29
docker.io/library/mysql:5.7.29
[root@ubuntu1804 ~]#docker pull mysql:5.6.47

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