創建鏡像三種方法
Docker鏡像創建方法有三種，分別爲基於已有鏡像創建、基於本地模板創建以及基於Dockerfile創建。
通過Dockerfile創建鏡像
這裏主要記錄下基於Dockerfile創建方法，Dockerfile是由一組指令組成的文件，其中每條指令對應Linux中的一條命令，Docker程序將讀取Dockerfile中的指令生成指定鏡像。
Dockerfile結構大致分爲四個部分：基礎鏡像信息、維護者信息、鏡像操作指令和容器啓動時執行指令 。Dockerfile每行支持一條指令，每條指令可帶多個參數，支持使用以#號開頭的註釋。
Docker操作指令
| 指令 | 含義 |
|---|---|
| FROM鏡像 | 指定新鏡像所基於的鏡像，必須爲第一條指令 |
| MAINTAINER 名字 | 新鏡像的維護人信息 |
| RUN 命令 | 在所基於的鏡像上執行命令，並提交到新鏡像中 |
| EXPOSE端口號 | 指定新鏡像加載到Docker時開啓的端口號 |
| ENV 環境變量 變量值 | 設置一個環境變量的值，會被後面的RUN使用 |
| ADD 源文件/目錄 目標文件/目錄 | 將源文件複製到目標文件，源文件要與Docker位於同一目錄下，或者爲一個URL |
| COPY 源文件/目錄 目標文件/目錄 | 將本地主機上的源文件/目錄複製到目標地點，源文件/目錄要與Dockerfile在同一目錄下 |
| VOLUME["目錄"] | 在容器中創建一個掛載點 |
| USER 用戶名 /UID | 指定運行容器時的用戶 |
| WORKDIR 路徑 | 爲後續的RUN、CMD、ENTRYPOINT指定工作目錄 |
| ONBUILD命令 | 指定所生成的鏡像作爲一個基礎鏡像時所要運行的命令 |
| CMD["要運行的程序"，"參數1"，"參數2"] | 指定啓動容器時運行的命令或腳本，只能有一條CMD命令，多條時只有最後一條被執行 |
以下通過Dockerfile來創建httpd鏡像
1.創建鏡像工作目錄並進入
mkdir apache
cd apache/2.創建並編寫dockerfile文件
vim Dockerfile
#基於centos鏡像
FROM centos
#維護人的信息
MAINTAINER The CentOS Project <[email protected]>
#安裝httpd軟件包
RUN yum -y update
RUN yum -y install httpd
#開啓80端口
EXPOSE 80
#複製網站首頁文件至鏡像中web站點下
ADD index.html /var/www/html/index.html
#複製該腳本至鏡像中，並修改其權限
ADD run.sh /run.sh
RUN chmod 775 /run.sh
#當啓動容器時執行的腳本文件
CMD ["/run.sh"]
3.創建腳本文件
vim run.sh
#!/bin/bash
#清空httpd緩存文件
rm -rf /run/httpd/*
#啓動httpd服務
exec /usr/sbin/apachectl -D FOREGROUND4.創建網站首頁文件
echo "Thiss is Nginx webapp." > index.html5.查看當前目錄文件列表
ls
6.通過Dockerfile文件生成鏡像
docker build -t httpd:centos .
Sending build context to Docker daemon 4.096kB
Step 1/9 : FROM centos
---> 5182e96772bf
Step 2/9 : MAINTAINER The CentOS Project <[email protected]>
---> Running in 6d7c8eae519d
---> 46fc589066ff
Removing intermediate container 6d7c8eae519d
Step 3/9 : RUN yum -y update
---> Running in 444105af6041
Loaded plugins: fastestmirror, ovl
Determining fastest mirrors
* base: mirrors.zju.edu.cn
* extras: mirrors.zju.edu.cn
* updates: mirrors.cn99.com
Resolving Dependencies
--> Running transaction check
---> Package centos-release.x86_64 0:7-5.1804.1.el7.centos will be updated
---> Package centos-release.x86_64 0:7-5.1804.4.el7.centos will be an update
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Updating:
centos-release x86_64 7-5.1804.4.el7.centos updates 25 k
Transaction Summary
================================================================================
Upgrade 1 Package
Total download size: 25 k
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
Public key for centos-release-7-5.1804.4.el7.centos.x86_64.rpm is not installed
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
warning: /var/cache/yum/x86_64/7/updates/packages/centos-release-7-5.1804.4.el7.centos.x86_64.rpm:Header V3 RSA/SHA256 Signature, key ID f4a80eb5: NOKEY
Importing GPG key 0xF4A80EB5:
Userid : "CentOS-7 Key (CentOS 7 Official Signing Key) <[email protected]>"
Fingerprint: 6341 ab27 53d7 8a78 a7c2 7bb1 24c6 a8a7 f4a8 0eb5
Package : centos-release-7-5.1804.1.el7.centos.x86_64 (@Updates)
From : /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Updating : centos-release-7-5.1804.4.el7.centos.x86_64 1/2
Cleanup : centos-release-7-5.1804.1.el7.centos.x86_64 2/2
Verifying : centos-release-7-5.1804.4.el7.centos.x86_64 1/2
Verifying : centos-release-7-5.1804.1.el7.centos.x86_64 2/2
Updated:
centos-release.x86_64 0:7-5.1804.4.el7.centos
Complete!
---> 8a4bb67da908
Removing intermediate container 444105af6041
Step 4/9 : RUN yum -y install httpd
---> Running in 982f008f5f3c
Loaded plugins: fastestmirror, ovl
Loading mirror speeds from cached hostfile
* base: mirrors.zju.edu.cn
* extras: mirrors.zju.edu.cn
* updates: mirrors.cn99.com
Resolving Dependencies
--> Running transaction check
---> Package httpd.x86_64 0:2.4.6-80.el7.centos.1 will be installed
--> Processing Dependency: httpd-tools = 2.4.6-80.el7.centos.1 for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Processing Dependency: system-logos >= 7.92.1-1 for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Processing Dependency: /etc/mime.types for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Processing Dependency: libaprutil-1.so.0()(64bit) for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Processing Dependency: libapr-1.so.0()(64bit) for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Running transaction check
---> Package apr.x86_64 0:1.4.8-3.el7_4.1 will be installed
---> Package apr-util.x86_64 0:1.5.2-6.el7 will be installed
---> Package centos-logos.noarch 0:70.0.6-3.el7.centos will be installed
---> Package httpd-tools.x86_64 0:2.4.6-80.el7.centos.1 will be installed
---> Package mailcap.noarch 0:2.1.41-2.el7 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
httpd x86_64 2.4.6-80.el7.centos.1 updates 2.7 M
Installing for dependencies:
apr x86_64 1.4.8-3.el7_4.1 base 103 k
apr-util x86_64 1.5.2-6.el7 base 92 k
centos-logos noarch 70.0.6-3.el7.centos base 21 M
httpd-tools x86_64 2.4.6-80.el7.centos.1 updates 90 k
mailcap noarch 2.1.41-2.el7 base 31 k
Transaction Summary
================================================================================
Install 1 Package (+5 Dependent packages)
Total download size: 24 M
Installed size: 31 M
Downloading packages:
--------------------------------------------------------------------------------
Total 1.1 MB/s | 24 MB 00:21
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : apr-1.4.8-3.el7_4.1.x86_64 1/6
Installing : apr-util-1.5.2-6.el7.x86_64 2/6
Installing : httpd-tools-2.4.6-80.el7.centos.1.x86_64 3/6
Installing : centos-logos-70.0.6-3.el7.centos.noarch 4/6
Installing : mailcap-2.1.41-2.el7.noarch 5/6
Installing : httpd-2.4.6-80.el7.centos.1.x86_64 6/6
Verifying : mailcap-2.1.41-2.el7.noarch 1/6
Verifying : httpd-tools-2.4.6-80.el7.centos.1.x86_64 2/6
Verifying : apr-util-1.5.2-6.el7.x86_64 3/6
Verifying : httpd-2.4.6-80.el7.centos.1.x86_64 4/6
Verifying : apr-1.4.8-3.el7_4.1.x86_64 5/6
Verifying : centos-logos-70.0.6-3.el7.centos.noarch 6/6
Installed:
httpd.x86_64 0:2.4.6-80.el7.centos.1
Dependency Installed:
apr.x86_64 0:1.4.8-3.el7_4.1
apr-util.x86_64 0:1.5.2-6.el7
centos-logos.noarch 0:70.0.6-3.el7.centos
httpd-tools.x86_64 0:2.4.6-80.el7.centos.1
mailcap.noarch 0:2.1.41-2.el7
Complete!
---> d3f0d6f963cb
Removing intermediate container 982f008f5f3c
Step 5/9 : EXPOSE 80
---> Running in b511725feca7
---> 7f7887f5875e
Removing intermediate container b511725feca7
Step 6/9 : ADD index.html /var/www/html/index.html
---> 3c5953c9fd43
Removing intermediate container 85dad653f265
Step 7/9 : ADD run.sh /run.sh
---> 41980651502b
Removing intermediate container 91ff7e24daa4
Step 8/9 : RUN chmod 775 /run.sh
---> Running in 7aebb5d8f194
---> f673460e23c7
Removing intermediate container 7aebb5d8f194
Step 9/9 : CMD /run.sh
---> Running in 9c0f5c4f1e32
---> 551b9fc524ba
Removing intermediate container 9c0f5c4f1e32
Successfully built 551b9fc524ba
Successfully tagged httpd:centos7.鏡像文件加載到容器中運行
docker run -d -p 80:80 --name=httpd httpd:centos
8.查看運行中的容器
docker ps
9.運行瀏覽器測試httpd服務
http://192.168.96.44:80
