基于Dockerfile构建镜像
1. Dockerfile:source code for building Docker file
Docker可以通过从Dockerfile文件中读取指令自动构建镜像
Dockerfile是一个文本文档,它包含用户可以在命令行上调用的所有命令来组装映像
使用Docker build命令,用户可以通过逐条执行几条命令自动创建镜像
2. Dockerfile语法格式:
首行必须是以#开头的行
不区分大小写,但约定俗成的惯例都是使用全部大写。
Docker按顺序在Dockerfile中运行指令
第一个指令必须是“FROM”,以便指定要从其中构建的基本映像
3. 环境变量(使用ENV语句声明)也可以在某些指令中使用,作为由Dockerfile解释的变量。
在Dockerfile中,环境变量可以是$variable_name或${variable_name}
${variable_name}语法还支持一些标准bash修饰符
${variable:-word}表示,如果设置了变量,那么结果将是该值。如果变量未设置,则结果为word。
${variable:+word}表示如果设置了变量,那么结果将是word,否则结果将是空字符串。
4. .dockerignore文件
在工作目录中若有子目录,而子目录中有些文件不想引用,就可以用.dockerignore来隐藏文件。
.dockerignore文件内指明不引用的文件。
5. FROM
用来指定基础镜像,若指定的镜像不存在,会先到Docker Hub中下载
语法:
FROM <image> [AS <name>] #[AS <name>]:别名
FROM <image>[:<tag>] [AS <name>] #tag:标签
FROM <image> [@<digest>] [AS <name>] #digest:哈希码
6. docker build命令
Build an image from a Dockerfile
Options
-t, --tag list Name and optionally a tag in the 'name:tag' format
-m, --memory bytes Memory limit
-c, --cpu-shares int CPU shares (relative weight)
7. LABEL
添加镜像文件的元数据,可出现多次,强烈建议只使用一条,因为一条指令会添加一个层,层数越多,运行效率越低。
语法格式:
LABEL <key>=<value> <key>=<value> <key>=<value>... #可指定多个LABEL
LABEL <key> <value> #只可指定一个LABEL,第一个空格后的内容都会被当作value
示例
只修改一个镜像的FROM、LABEL
创建工作目录image
[root@docker ~]# mkdir image[root@docker ~]# cd image
编辑Dockerfile文件,添加以下内容:
[root@docker image]# vim Dockerfile#Test Image BuildFROM alpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"
制作镜像:
[root@docker image]# docker build .Sending build context to Docker daemon 2.048kBStep 1/2 : FROM alpine ---> 3fd9065eaf02Step 2/2 : LABEL maintainer="lixinkuan " --->Runningine1ce9acfc453Removing intermediate container e1ce9acfc453 ---> 1deb17a1af32Successfully built 1deb17a1af32
查看:REPOSITORY和TAG都为空的即为新创建的镜像文件
[root@docker image]#dockerimagelsREPOSITORYTAGIMAGEIDCREATEDSIZE 1deb17a1af325minutesago4.15MBnginxlatestcd5239a0906a3weeksago109MBbusyboxlatest8c811b4aec355weeksago1.15MBhttpd2.4fb2f3851a9718weeksago178MBalpinelatest3fd9065eaf025monthsago4.15MB
创建docker镜像时,可使用-t后跟 'name:tag' 指定TAG
也可用如下命令添加标签:
[root@docker image]# docker image tag 1deb17a1af32 alpine:lxk[root@docker image]# docker imagesREPOSITORY TAG IMAGE ID CREATED SIZEalpine lxk1deb17a1af325minutes ago4.41MB
8. COPY
用于从Docker宿主机复制文件至创建的新映像文件
语法:
COPY <src> ... <dest>
COPY ["",... ""]
<src>:要复制的源文件或目录,支持使用通配符
<dest>:目标路径,即正在创建的image的文件系统路径;建议为<dest>使用绝对路径,否则,COPY指定则以WORKDIR为其起始路径
注意:在路径中有空白字符时,通常使用第二种格式
文件复制准则:
<src>必须是build上下文中的路径,不能是其父目录中的文件
如果<src>是目录,则其内部文件或子目录会被递归复制,但<src>目录自身不会被复制
如果指定了多个<src>,或在<src>中使用了通配符,则<dest>必须是一个目录,且必须以/结尾
如果<dest>事先不存在,它将会被自动创建,这包括其父目录路径
示例:复制单个文件
在image目录下为index.html添加内容:
[root@docker image]# echo '<h1>hello,docker!</h1>' > index.html
编辑Dockerfile文件,添加语句:
[root@docker image]# vim Dockerfile #Test Image BuildFROM alpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"COPY index.html/var/www/html/
用alpine启动一个容器,查看是否有/var/www/html目录
[root@docker image]# docker run -it --name a1 alpine/# ps aux PID USER TIME COMMAND1root0:00/bin/sh7root0:00ps aux/# ls /var/www/htmlls: /var/www/html: No such fileordirectory
制作镜像
[root@docker image]# docker build -t cpindex:latest .Sending build context to Docker daemon 3.072kBStep 1/3 : FROM alpine ---> 3fd9065eaf02Step 2/3 : LABEL maintainer="lixinkuan " --->Runningin9d96e0655a82Removing intermediate container 9d96e0655a82 ---> 56049399eb78Step 3/3 : COPY index.html /var/www/html/ ---> bace8e55c97bSuccessfully built bace8e55c97bSuccessfully tagged cpindex:latest
查看制作的镜像:
[root@docker image]# docker image lsREPOSITORY TAG IMAGE ID CREATED SIZEcpindex latest bace8e55c97b52seconds ago4.15MB
以制作的镜像启动一个容器,并查看文件是否存在
[root@docker image]# docker run --name copyfile -it --rm cpindex:latest/# ls /var/www/htmlindex.html/# cat /var/www/html/index.html
hello,docker!
示例:复制目录下的多个文件至目录
复制一个目录至/root/image下
[root@docker image]# cp -r /etc/default/ ./ [root@docker image]# lsdefaultDockerfile index.html[root@docker image]# ls default/grub kibana nss useradd
修改Dockerfile文件为以下内容:
#Test Image BuildFROM alpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"COPYdefault/tmp/
制作镜像:
[root@docker image]# docker build -t cpdir:latest ./Sending build context to Docker daemon 9.216kBStep 1/3 : FROM alpine ---> 3fd9065eaf02Step 2/3 : LABEL maintainer="lixinkuan " ---> Using cache ---> 56049399eb78Step 3/3 : COPY default /tmp/ ---> 18cacf50aef9Successfully built 18cacf50aef9Successfully tagged cpdir:latest
查看并验证:
[root@docker image]# docker image lsREPOSITORY TAG IMAGE ID CREATED SIZEcpdir latest18cacf50aef924seconds ago4.15MB[root@docker image]# docker run --name cpdir -it --rm cpdir:latestWARNING: IPv4 forwardingisdisabled. Networking willnotwork./# ls /tmpgrub kibana nss useradd
示例:使用数组格式创建配置文件
修改配置文件如下:
#Test Image BuildFROMalpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"COPY ["default","/tmp/default"]
创建镜像并验证
[root@docker image]# docker build -t cp:latest ./Sending build context to Docker daemon9.216kBStep1/3: FROM alpine --->3fd9065eaf02Step2/3: LABEL maintainer="lixinkuan <lixinkuan@163.com>"---> Using cache --->56049399eb78Step3/3: COPY ["default","/tmp/default"] ---> bf0799319943Successfully built bf0799319943Successfully tagged cp:latest[root@docker image]# docker run --name cp -it --rm cp:latest/# cd /tmp/tmp# lsdefault/tmp # cd default//tmp/default# lsgrub kibana nss useradd/tmp/default# exit
9. ADD
ADD类似于COPY指令,ADD支持tar文件和URL路径
Syntax
ADD <src>...<dest>
ADD ["<src>"..."<dest>"]
操作准则:
同COPY指令
如果<src>为URL且<dest>不以/结尾,则<src>指定的文件将被下载并直接被创建为<dest>;如果<dest>以/结尾,则文件名URL指定的文件将被直接下载并保存为<dest>/<filename>
如果<src>是一个本地系统上的压缩格式的tar文件,它将被展开为一个目录,其行为类似于“tar -x”命令;然而,通过URL获取到的tar文件将不会自动展开;
如果<src>有多个,或其间接或直接使用了通配符,则<dest>必须是一个以/结尾的目录路径;如果<dest>不以/结尾,则其被视作一个普通文件,<src>的内容将被直接写入到<dest>
示例:下载一个文件至镜像文件
在工作目录下编写Dockerfile文件(使用URL时,用ftp协议失败)
#Test Image BuildFROM alpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"COPY ["default","/tmp/default"]ADDhttps://mirrors.aliyun.com/centos/7.5.1804/os/x86_64/Packages/zsh-5.0.2-28.el7.x86_64.rpm /tmp/
创建镜像文件
[root@docker image]# docker build -t zsh:latest ./Sending build context to Docker daemon 9.216kBStep 1/4 : FROM alpine ---> 3fd9065eaf02Step 2/4 : LABEL maintainer="lixinkuan " ---> Using cache ---> 56049399eb78Step 3/4 : COPY ["default","/tmp/default"] ---> Using cache ---> bf0799319943Step 4/4 : ADD https://mirrors.aliyun.com/centos/7.5.1804/os/x86_64/Packages/zsh-5.0.2-28.el7.x86_64.rpm /tmp/Downloading [==================================================>] 2.494MB/2.494MB ---> 538ab9c6983eSuccessfully built 538ab9c6983eSuccessfully tagged zsh:latest
创建容器并查看
[root@docker image]# docker run -it --name zsh --rm zsh:latest/# cd /tmp/tmp# lsdefaultzsh-5.0.2-28.el7.x86_64.rpm
示例:ADD一个压缩包至镜像文件
复制压缩包至工作目录,并在工作目录编辑Dockerfile文件
[root@docker image]# cp /root/wordpress-4.8.1-zh_CN.tar.gz ./[root@docker image]# vim Dockerfile #Test Image BuildFROM alpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"ADD wordpress-4.8.1-zh_CN.tar.gz/tmp/
制作镜像文件
[root@docker image]# docker build -t wordpress:latest ./Sending build context to Docker daemon 8.652MBStep 1/3 : FROM alpine ---> 3fd9065eaf02Step 2/3 : LABEL maintainer="lixinkuan " ---> Using cache ---> 56049399eb78Step 3/3 : ADD wordpress-4.8.1-zh_CN.tar.gz /tmp/ ---> 58c32caba31eSuccessfully built 58c32caba31eSuccessfully tagged wordpress:latest
创建容器并查看
[root@docker image]# docker run --name a1 -it --rm wordpress:latest/# ls /tmp/wordpress/index.php wp-admin wp-content wp-load.php wp-signup.phplicense.txt wp-blog-header.php wp-cron.php wp-login.php wp-trackback.phpreadme.html wp-comments-post.php wp-includes wp-mail.php xmlrpc.phpwp-activate.php wp-config-sample.php wp-links-opml.php wp-settings.php/# exit
10. WORKDIR
用于为Dockerfile中所有的RUN、CMD、ENTRYPOINT、COPY和ADD指定设定工作目录
Syntax
WORKDIR
在Dockerfile文件中,WORKDIR指令可出现多次,其路径也可以为相对路径,不过,其是相对此前一个WORKDIR指令指定的路径
另外,WORKDIR也可调用由ENV指定定义的变量
例如:
WORKDIR /var/log
WORKDIR $STATEPATH
示例
在工作目录下编辑Dockerfile文件:
#Test Image BuildFROMalpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"WORKDIR /tmpADD wordpress-4.8.1-zh_CN.tar.gz src
创建镜像:
[root@docker image]# docker build -t wordpress:v0.1 ./Sending build context to Docker daemon 8.652MBStep 1/4 : FROM alpine ---> 3fd9065eaf02Step 2/4 : LABEL maintainer="lixinkuan " ---> Using cache ---> 56049399eb78Step 3/4 : WORKDIR /tmpRemoving intermediate container 08bef4630472 ---> 54f97eda6b49Step 4/4 : ADD wordpress-4.8.1-zh_CN.tar.gz src ---> 0811aff4fa7dSuccessfully built 0811aff4fa7dSuccessfully tagged wordpress:v0.1
创建容器后,默认工作路径就是WORKDIR所指的目录/tmp
[root@docker image]# docker run --name a1 -it --rm wordpress:v0.1/tmp# lssrc/tmp # ls src/wordpress/tmp # ls src/wordpress/index.php wp-admin wp-content wp-load.php wp-signup.phplicense.txt wp-blog-header.php wp-cron.php wp-login.php wp-trackback.phpreadme.html wp-comments-post.php wp-includes wp-mail.php xmlrpc.phpwp-activate.php wp-config-sample.php wp-links-opml.php wp-settings.php/tmp# exit
11. VOLUME
用于在image中创建一个挂载点目录,以挂载Docker host上的卷或其它容器上的卷
Syntax
VOLUME <mountpoint>
VOLUME ["<mountpoint>"]
如果挂载点目录路径下此前有文件存在,docker run命令会把原文件隐藏.
如果此前挂载点不存在,docker 会自动创建该目录.
挂载点下文件变化都可以在宿主机查看
查看方法:
docker volume ls #查看宿主机所有挂载的目录
docker inspect -f {{.Mounts}} a1 #通过查看指定容器信息查看挂载点路径
示例
在需要挂载的目录下提供文件
[root@docker image]# echo "hello,test dockerfile" > /var/www/html/index.html
在工作目录下编辑Dockerfile文件
#Test Image BuildFROM alpineLABEL maintainer="lixinkuan "#WORKDIR /tmp#ADD wordpress-4.8.1-zh_CN.tar.gz src/VOLUME /var/www/html
创建镜像文件
[root@docker image]# docker build -t file:v0.1 ./Sending build context to Docker daemon 8.651MBStep 1/3 : FROM alpine ---> 3fd9065eaf02Step 2/3 : LABEL maintainer="lixinkuan " ---> Using cache ---> 56049399eb78Step 3/3 : VOLUME /var/www/html ---> [Warning] IPv4 forwarding is disabled. Networking will not work. --->Runninginda84d9f4ca1eRemoving intermediate container da84d9f4ca1e ---> b26c2d7ea64cSuccessfully built b26c2d7ea64cSuccessfully tagged file:v0.1
创建容器:
[root@docker image]# docker run --name a1 -it --rm file/# cd /var/www/html//var/www/html# echo abc > index.html/var/www/html# cat index.htmlabc
查看宿主机上的文件:
[root@docker ~]# docker volume ls #查看本机所有容器挂载的目录DRIVER VOLUME NAMElocal6368d0a0b462f5329a4b3bdcb7030e0d6f724bf9f801386f87fdac7660cd1735[root@docker ~]# docker inspect -f {{.Mounts}} a1 #查看a1容器的挂载文件路径[{volume6368d0a0b462f5329a4b3bdcb7030e0d6f724bf9f801386f87fdac7660cd1735 /var/lib/docker/volumes/6368d0a0b462f5329a4b3bdcb7030e0d6f724bf9f801386f87fdac7660cd1735/_data /var/www/htmllocaltrue }][root@docker ~]# cd /var/lib/docker/volumes/6368d0a0b462f5329a4b3bdcb7030e0d6f724bf9f801386f87fdac7660cd1735/_data/[root@docker _data]# lsindex.html[root@docker _data]# cat index.html abc#该内容与容器中index.html内容一样
12. EXPOSE
用于为容器打开指定要监听的端口以实现与外部通信
实质是通过iptables添加DNAT规则,把外网主机访问宿主机的请求转发至指定容器.
需要宿主机开启核心转发功能.
可通过iptables -t nat -nvL查看添加的规则.
通过Dockerfile制作镜像时若不用EXPOSE指定要暴露的端口,可用以下两种方法暴露端口:
容器运行后,自行添加DNAT规则实现端口暴露.
docker run时使用-p选项指定暴露的端口.
docker run时使用-P选项暴露所有容器内监听的端口.
docker run时,使用-p选项指定的优先级要高于Dockerfile制作镜像时指定要暴露的端口.
Syntax
EXPOSE [/] [[/] ...]
<protocol>用于指定传输层协议,可为tcp或udp二者之一,默认为TCP协议
EXPOSE指令可一次指定多个端口,例如
EXPOSE 11211/udp 11211/tcp
不用EXPOSE时,宿主机内容器若要被外网主机访问的情况
下载redis:4-alpine
[root@docker ~]# docker pull redis:4-alpine4-alpine: Pulling from library/redisff3a5c916c92: Pull complete 5fbab8756652: Pull complete ff7d4663b06c: Pull complete 0b5cf71258c2: Pull complete 54bbb9bad8ba: Pull complete 8fe9a341d124: Pull complete Digest: sha256:686ab026fae07b3b99a8e74210c361714a80311ecc55f23b349ae930ed2f5a95Status: Downloaded newer image for redis:4-alpine[root@docker ~]# docker imagesREPOSITORY TAG IMAGE ID CREATED SIZEredis 4-alpine caaeda72bf8f 12 days ago 27.8MB
运行redis镜像
[root@docker ~]# docker run --name db1 -d --rm -p 6379 redis:4-alpine881d5648c7388449a39c67024206c5710b1538f4c941039fa3905bb601b09699[root@docker ~]# docker exec -it db1 ifconfigeth0Linkencap:Ethernet HWaddr02:42:AC:11:00:02inetaddr:172.17.0.2Bcast:172.17.255.255Mask:255.255.0.0UP BROADCAST RUNNING MULTICASTMTU:1500Metric:1RXpackets:8errors:0dropped:0overruns:0frame:0TXpackets:0errors:0dropped:0overruns:0carrier:0collisions:0txqueuelen:0RXbytes:648(648.0B) TXbytes:0(0.0B)lo Linkencap:Local Loopback inetaddr:127.0.0.1Mask:255.0.0.0UP LOOPBACK RUNNINGMTU:65536Metric:1RXpackets:0errors:0dropped:0overruns:0frame:0TXpackets:0errors:0dropped:0overruns:0carrier:0collisions:0txqueuelen:1RXbytes:0(0.0B) TXbytes:0(0.0B)[root@docker ~]# docker exec -it db1 /bin/sh/data# netstat -tnlActive Internet connections (only servers)Proto Recv-Q Send-Q Local Address Foreign Address State tcp000.0.0.0:63790.0.0.0:*LISTEN tcp00:::6379:::*LISTEN /data#
查看映射的端口
[root@docker ~]# docker container port db16379/tcp ->0.0.0.0:32768
外网主机访问本地宿主机容器
[root@node1 tmp]#redis-cli-h192.168.1.106-p32768192.168.1.106:32768>select1OK192.168.1.106:32768[1]>setmykeyhiOK192.168.1.106:32768[1]>keys*1) "mykey"192.168.1.106:32768[1]>exit
查看本地容器内是否有数据
[root@docker ~]# docker exec -it db1 /bin/sh/data# redis-cli 127.0.0.1:6379>select1OK127.0.0.1:6379[1]>keys *1)"mykey"127.0.0.1:6379[1]>exit/data# exit
开启自动端口暴露
在工作目录下编写Dockerfile文件
#Test Image BuildFROMredis:4-alpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"EXPOSE6379/tcp26379/tcp
制作镜像文件
[root@docker images]# docker build -t expose_db:latest ./Sending build context to Docker daemon 8.645MBStep 1/3 : FROM redis:4-alpine ---> caaeda72bf8fStep 2/3 : LABEL maintainer="lixinkuan " --->Runninginf43f9e43b27aRemoving intermediate container f43f9e43b27a ---> e98bb940a8a2Step 3/3 : EXPOSE 6379/tcp 26379/tcp --->Runninginf53a9be4f661Removing intermediate container f53a9be4f661 ---> ea40417716a0Successfully built ea40417716a0Successfully tagged expose_db:latest
运行并查看效果
[root@docker images]# docker run --name a1 -d --rm -P redis_expose:latestad1225390f8f246cc5bde693ea99b120ee3a2f474416603b0797cda94787cc03[root@docker images]# docker container port a16379/tcp ->0.0.0.0:32772
换一台主机连接数据库查看
[root@node1 ~]#redis-cli-h192.168.200.45-p32772192.168.200.45:32772>select1OK192.168.200.45:32772[1]>keys*(emptylistorset)192.168.200.45:32772[1]>settestdockerfileOK192.168.200.45:32772[1]>keys*1) "test"192.168.200.45:32772[1]>gettest"dockerfile"
在a1容器上查看:
[root@docker images]# docker exec -it a1 /bin/sh/data# redis-cli 127.0.0.1:6379>select1OK127.0.0.1:6379[1]>get test"dockerfile"
示例:验证Dockerfile与docker run时使用-p的优先级
编辑Dockerfile
[root@docker images]# cat Dockerfile #Test Image BuildFROM redis:4-alpineLABEL maintainer="lixinkuan <lixinkuan@163.com>"EXPOSE6379/tcp80/tcp
制作镜像:
[root@docker images]# docker build -t expose_port .Sending build context to Docker daemon 8.645MBStep 1/3 : FROM redis:4-alpine ---> caaeda72bf8fStep 2/3 : LABEL maintainer="lixinkuan " ---> Using cache ---> 188775dd2e3eStep 3/3 : EXPOSE 6379/tcp 80/tcp --->Runninginb0f5bfbaafaeRemoving intermediate container b0f5bfbaafae ---> 165e707c2b23Successfully built 165e707c2b23Successfully tagged expose_port:latest
运行容器时指定要暴露的端口:
[root@docker images]# docker run --name db1 -d --rm -p 25 expose_porte00f3e304103954c00651d44b00ae9961608900e0d5688eee4c08f140340f480[root@docker images]# docker container port db125/tcp ->0.0.0.0:32779
查看防火墙规则,只有暴露25端口的DNAT规则
[root@docker images]# iptables -t nat -nvLChain DOCKER (2 references) pkts bytes target prot optinoutsourcedestination 0 0 RETURN all -- docker0 * 0.0.0.0/0 0.0.0.0/0 0 0 DNAT tcp -- !docker0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:32779 to:172.17.0.2:25
13. ENV
用于为镜像定义所需的环境变量,并可被Dockerfile文件中位于其后的其它指令(如ENV、ADD、COPY等)所调用
调用格式为$variable_name或${variable_name}
Syntax
ENV <key> <value>
ENV <key>=<value> ...
第一种格式中,<key>之后的所有内容均会被视作其<value>的组成部分,因此,一次只能设置一个变量
第二种格式可用一次设置多个变量,每个变量为一个"<key>=<value>"的键值对,如果<value>中包含空格,可以以反斜线()进行转义,也可通过对<value>加引号进行标识;另外,反斜线也可用于续行
定义多个变量时,建议使用第二种方式,以便在同一层中完成所有功能
示例
编辑Dockerfile文件
FROMbusyboxLABEL maintainer="lixinkuan <lixinkuan@163.com>"ENV DOCROOT="/data/web/html/"COPY index.html${DOCROOT}VOLUME${DOCROOT}
提供index及所需挂载目录:
[root@docker bbox]# mkdir -pv /data/web/htmlmkdir: created directory ‘/data’mkdir: created directory ‘/data/web’mkdir: created directory ‘/data/web/html’[root@docker bbox]# echo hello Docker > index.html[root@docker bbox]# cat index.htmlhello Docker
制作镜像:
[root@docker bbox]# docker build -t bbox_file:latest ./Sending build context to Docker daemon 3.072kBStep 1/5 : FROM busyboxlatest: Pulling from library/busybox07a152489297: Pull complete Digest: sha256:141c253bc4c3fd0a201d32dc1f493bcf3fff003b6df416dea4f41046e0f37d47Status: Downloaded newer image for busybox:latest ---> 8c811b4aec35Step 2/5 : LABEL maintainer="lixinkuan " --->Runningin87a1f2c22ad6Removing intermediate container 87a1f2c22ad6 ---> 56f723d6220cStep 3/5 : ENV DOCROOT="/data/web/html/" --->Runningin21fd1fcb0474Removing intermediate container 21fd1fcb0474 ---> c095f8dd8418Step 4/5 : COPY index.html ${DOCROOT} --->ee77cd16629aStep 5/5 : VOLUME ${DOCROOT} --->Runningin00474fde8b85Removing intermediate container 00474fde8b85 ---> d51ea735fdd3Successfully built d51ea735fdd3Successfully tagged bbox_file:latest
运行容器并查看
[root@docker bbox]# docker run --name a1 -it --rm bbox_file:latest/# ls /data/web/htmlindex.html/# cat /data/web/html/index.htmlhello Docker
另启终端查看挂载的卷:
[root@docker ~]# docker volume lsDRIVER VOLUME NAMElocal1dcd37d2c4f2e6a71e0b96a385714ff01cad5d578e396c9b012922e9993aecbflocalb2df5fcd0e1aa58c403d2e8f0ec880feb7dcb1a80a688697e76122adec55e789[root@docker ~]# docker inspect -f {{.Mounts}} a1[{volume1dcd37d2c4f2e6a71e0b96a385714ff01cad5d578e396c9b012922e9993aecbf /var/lib/docker/volumes/1dcd37d2c4f2e6a71e0b96a385714ff01cad5d578e396c9b012922e9993aecbf/_data /data/web/htmllocaltrue }]
14. CMD与RUN
CMD
用于定义镜像启动为容器时默认运行的应用程序。
类似于RUN指令,CMD指令也可用于运行任何命令或应用程序,不过,二者的运行时间点不同
RUN指令运行于映像文件构建过程中,而CMD指令运行于基于Dockerfile构建出的新映像文件启动一个容器时
CMD指令的首要目的在于为启动的容器指定默认要运行的程序,且其运行结束后,容器也将终止;不过,CMD指定的命令其可以被docker run的命令行选项所覆盖
在Dockerfile中可以存在多个CMD指令,但仅最后一个会生效
Syntax
CMD <command>
CMD [“<executable>”, “<param1>”, “<param2>”]
CMD ["<param1>","<param2>"]
前两种语法格式的意义同RUN
第三种则用于为ENTRYPOINT指令提供默认参数
RUN
指定docker build过程中运行的程序。必须是镜像中存在的命令。
Syntax
RUN <command>
RUN ["<executable>", "<param1>", "<param2>"]
第一种格式中,<command>通常是一个shell命令,且以“/bin/sh -c”来运行它,这意味着此进程在容器中的PID不为1,不能接收Unix信号,因此,当使用docker stop <container>命令停止容器时,此进程接收不到SIGTERM信号;
第二种语法格式中的参数是一个JSON格式的数组,其中<executable>为要运行的命令,后面的<paramN>为传递给命令的选项或参数;然而,此种格式指定的命令不会以“/bin/sh -c”来发起,因此常见的shell操作如变量替换以及通配符(?,*等)替换将不会进行;不过,如果要运行的命令依赖于此shell特性的话,可以将其替换为类似下面的格式。
示例:RUN ["/bin/bash", "-c", "<executable>", "<param1>"]
示例1:基于centos基础镜像创建一个运行nginx的镜像
编辑Dockerfile文件:
FROM centosLABEL maintainer="lixinkuan <lixinkuan@163.com>"COPYbase.repo epel.repo /etc/yum.repos.d/RUN yum -y install nginx \ && yum clean all \ && rm -rf /var/cache/yum
提供base.repo epel.repo文件:
[root@docker nginx]# wget lixinkuan.top/base.repo--2018-06-3011:29:08--http://lixinkuan.top/base.repoResolving lixinkuan.top (lixinkuan.top)...47.94.102.99Connecting to lixinkuan.top (lixinkuan.top)|47.94.102.99|:80... connected.HTTP request sent, awaiting response...200OKLength:630Savingto:‘base.repo’100%[=================================================================================>]630--.-K/sin0s2018-06-3011:29:08 (87.9MB/s) - ‘base.repo’ saved [630/630][root@docker nginx]# wget lixinkuan.top/epel.repo--2018-06-3011:29:16--http://lixinkuan.top/epel.repoResolving lixinkuan.top (lixinkuan.top)...47.94.102.99Connecting to lixinkuan.top (lixinkuan.top)|47.94.102.99|:80... connected.HTTP request sent, awaiting response...200OKLength:214Savingto:‘epel.repo’100%[=================================================================================>]214--.-K/sin0s2018-06-3011:29:16(44.2MB/s) - ‘epel.repo’ saved [214/214][root@docker nginx]# lsbase.repo Dockerfile epel.repo
创建镜像:
[root@docker nginx]# docker build -t nginx:v0.1 ./Sending build context to Docker daemon 4.608kBStep 1/4 : FROM centoslatest: Pulling from library/centos7dc0dca2b151: Pull complete Digest: sha256:b67d21dfe609ddacf404589e04631d90a342921e81c40aeaf3391f6717fa5322Status: Downloaded newer image for centos:latest ---> 49f7960eb7e4Step 2/4 : LABEL maintainer="lixinkuan " --->Runningin6b16128ed7caRemoving intermediate container 6b16128ed7ca ---> b6ef19a3311fStep 3/4 : COPY base.repo epel.repo /etc/yum.repos.d/ ---> e571c2837442Step 4/4 : RUN yum -y install nginx && yum clean all && rm -rf /var/cache/yum --->Runningin445372de8e8dLoaded plugins: fastestmirror, ovl.....执行安装过程省略...Cleaning repos: base epel extras updatesCleaning up everythingMaybe you want: rm -rf /var/cache/yum, to also free up space taken by orphaned data from disabled or removed reposCleaning up list of fastest mirrorsRemoving intermediate container 445372de8e8d ---> 5cf6e8e3517eSuccessfully built 5cf6e8e3517eSuccessfully tagged nginx:v0.1
创建容器并查看:
[root@docker nginx]#dockerrun--nameweb-itnginx:v0.1[root@5e7adf4282c1 /]#rpm-qnginxnginx-1.12.2-2.el7.x86_64#nginx已安装[root@5e7adf4282c1 /]#
示例2:以busybox制作一个挂载本地/data/web/html目录并自动运行httpd的镜像
在工作目录编辑Dockerfile文件
FROM busyboxLABEL maintainer="lixinkuan <lixinkuan@163.com>"ENV DOCROOT="/data/web/html/"COPY index.html${DOCROOT}VOLUME${DOCROOT}CMD /bin/httpd-f-h${DOCROOT}
提供index.html并创建要挂载的目录
[root@docker bbox]# echo hello Docker > index.html[root@docker bbox]# cat index.htmlhello Docker
创建镜像文件:
[root@docker bbox]# docker build -t web:v0.1 ./Sending build context to Docker daemon 3.072kBStep 1/6 : FROM busybox ---> 8c811b4aec35Step 2/6 : LABEL maintainer="lixinkuan " ---> Using cache ---> 56f723d6220cStep 3/6 : ENV DOCROOT="/data/web/html/" ---> Using cache ---> c095f8dd8418Step 4/6 : COPY index.html ${DOCROOT} ---> Using cache --->ee77cd16629aStep 5/6 : VOLUME ${DOCROOT} ---> Using cache ---> d51ea735fdd3Step 6/6 : CMD /bin/httpd -f -h ${DOCROOT} --->Runninginf2fa2b284306Removing intermediate container f2fa2b284306 ---> b8613217ad3cSuccessfully built b8613217ad3cSuccessfully tagged web:v0.1
以新创建的镜像文件运行容器并查看
[root@docker bbox]# docker run --name web -d --rm web:v0.17b71084ebd922728ebf21d22a4e5ff3462443761c82bc22c640764c6d4925b2a[root@docker bbox]# docker container inspect -f {{.Config.Cmd}} web[/bin/sh-c /bin/httpd -f -h ${DOCROOT}][root@docker bbox]# docker exec -it web /bin/sh/# ps auxPID USER TIME COMMAND1root0:00/bin/httpd -f -h /data/web/html/7root0:00/bin/sh13root0:00ps aux/# netstat -tnlActive Internet connections (only servers)Proto Recv-Q Send-Q Local Address Foreign Address State tcp00:::80:::*LISTEN
示例3:docker run 时不运行镜像默认进程,运行指定指令
查看当前镜像文件:
[root@docker bbox]#dockerimagesREPOSITORYTAGIMAGEIDCREATEDSIZEwebv0.1b8613217ad3c2hoursago1.15MB
以web:v0.1创建容器,不运行默认命令
[root@docker bbox]# docker run --name web -it --rm web:v0.1 /bin/sh/# netstat -tnlActive Internet connections (only servers)Proto Recv-Q Send-Q Local Address Foreign Address State /# ps auxPID USER TIME COMMAND1root0:00/bin/sh7root0:00ps aux
15. ENTRYPOINT
类似CMD指令的功能,用于为容器指定默认运行程序,从而使得容器像是一个单独的可执行程序
与CMD不同的是,由ENTRYPOINT启动的程序不会被docker run命令行指定的参数所覆盖,而且,这些命令行参数会被当作参数传递给ENTRYPOINT指定指定的程序
不过,docker run命令的--entrypoint选项的参数可覆盖ENTRYPOINT指令指定的程序
Syntax
ENTRYPOINT <command>
ENTRYPOINT ["<executable>", "<param1>", "<param2>"]
docker run命令传入的命令参数会覆盖CMD指令的内容并且附加到ENTRYPOINT命令最后做为其参数使用
Dockerfile文件中也可以存在多个ENTRYPOINT指令,但仅有最后一个会生效
示例1:
编辑Dockerfile文件
FROM busyboxLABEL maintainer="lixinkuan <lixinkuan@163.com>"VOLUME/data/web/html/COPY index.html/data/web/html/EXPOSE80/tcpENTRYPOINT ["/bin/httpd","-f","-h","/data/web/html"]
创建镜像
[root@docker bbox]# docker build -t web:v0.2 ./Sending build context to Docker daemon 3.072kBStep 1/6 : FROM busybox ---> 8c811b4aec35Step 2/6 : LABEL maintainer="lixinkuan " ---> Using cache ---> 56f723d6220cStep 3/6 : VOLUME /data/web/html/ --->Runningin3095065d0ebbRemoving intermediate container 3095065d0ebb ---> 36dc68fabc6fStep 4/6 : COPY index.html /data/web/html/ ---> e47f81ec7728Step 5/6 : EXPOSE 80/tcp --->Runninginf86f957ec882Removing intermediate container f86f957ec882 ---> 01a005644fe6Step 6/6 : ENTRYPOINT ["/bin/httpd","-f","-h","/data/web/html"] --->Runningin7a5f8b4f4acfRemoving intermediate container 7a5f8b4f4acf ---> 43d514096d34Successfully built 43d514096d34Successfully tagged web:v0.2
创建容器运行并查看:
[root@docker bbox]# docker exec -it web /bin/sh/# ps auxPID USER TIME COMMAND1root0:00/bin/httpd -f -h /data/web/html7root0:00/bin/sh13root0:00ps aux/# netstat -tnlActive Internet connections (only servers)Proto Recv-Q Send-Q Local Address Foreign Address State tcp00:::80:::*LISTEN /#
运行容器时指定执行/bin/sh
[root@docker bbox]# docker run --name web -it --rm web:v0.2 /bin/sh
换另一tty查看
[root@docker bbox]# docker exec -it web /bin/sh/# ps auxPID USER TIME COMMAND 1 root 0:00 /bin/httpd-f-h /data/web/html /bin/sh 7 root 0:00 /bin/sh 13 root 0:00 ps aux
并未执行/bin/sh,而是执行默认程序,/bin/sh被当作参数传递给/bin/httpd
示例:在docker run时使用entrypoint的时候更换默认运行的程序
--entrypoint string Overwrite the default ENTRYPOINT of the image
使用镜像web:v0.2创建容器运行时添加--entrypoint选项
[root@docker bbox]# docker run --name web -it --rm --entrypoint /bin/sh web:v0.2/# ps auxPID USER TIME COMMAND1root0:00/bin/sh7root0:00ps aux/# netstat -tnlActive Internet connections (only servers)Proto Recv-Q Send-Q Local Address Foreign Address State /#
示例
编辑Dockerfile文件
FROM busyboxLABEL maintainer="lixinkuan <lixinkuan@163.com>"ENV DOCROOT="/data/web/html/"MYPORT="80"COPY index.html ${DOCROOT} COPY entrypoint.sh /bin/COPY test.conf /etc/VOLUME ${DOCROOT}EXPOSE80/tcp#CMD /bin/httpd -f -h ${DOCROOT}#CMD ["/bin/sh","-c","/bin/httpd","-f","-h","${DOCROOT}"]ENTRYPOINT ["/bin/entrypoint.sh"]CMD["/bin/httpd","-f","-h","/data/web/html/"]
提供必须文件(脚本文件需加执行权限)
[root@docker bbox]# cat entrypoint.sh #!/bin/shsed -i"s@^PORT=.*@PORT=${MYPORT}@g"/etc/test.confexec"$@"[root@docker bbox]# cat test.conf PORT=8080
制作镜像:
[root@docker bbox]# docker build -t web:v0.3 ./Sending build context to Docker daemon 5.12kBStep 1/10 : FROM busybox ---> 8c811b4aec35Step 2/10 : LABEL maintainer="lixinkuan " ---> Using cache ---> 56f723d6220cStep 3/10 : ENV DOCROOT="/data/web/html/" MYPORT="80" --->Runninginf237100ec645Removing intermediate container f237100ec645 ---> f754b5dcea84Step 4/10 : COPY index.html ${DOCROOT} ---> 3c31424c9b3dStep 5/10 : COPY entrypoint.sh /bin/ ---> 46ec2f5ede8cStep 6/10 : COPY test.conf /etc/ ---> 7db53e00338aStep 7/10 : VOLUME ${DOCROOT} --->Runningin5ae02469f585Removing intermediate container 5ae02469f585 ---> 0e1e3e966318Step 8/10 : EXPOSE 80/tcp --->Runninginae76bcf870caRemoving intermediate container ae76bcf870ca ---> dea89896460dStep 9/10 : ENTRYPOINT ["/bin/entrypoint.sh"] --->Runningin6862bf4a336eRemoving intermediate container 6862bf4a336e ---> ca568e1ff983Step 10/10 : CMD ["/bin/httpd","-f","-h","/data/web/html/"] --->Runningin2aa5dea11848Removing intermediate container 2aa5dea11848 ---> 26bb44795880Successfully built 26bb44795880Successfully tagged web:v0.3
运行容器并查看配置文件是否被修改
[root@docker bbox]# docker run --name web -d --rm web:v0.36ec1f5a008e6a08047e8666f6ed3ad4673360805148789faf780baf335ee5637[root@docker bbox]# docker exec -it web /bin/sh/# netstat -tnlActive Internet connections (only servers)Proto Recv-Q Send-Q Local Address Foreign Address State tcp00:::80:::*LISTEN /# cat /etc/test.confPORT=80/# exit
示例:通过传递变量更改配置文件的方法:
[root@docker bbox]# docker run --name web1 -d --rm -e MYPORT=10080 web:v0.37e3b353e423839d598ee9423e881673066cf99626940b6590e78f34b7622834d[root@docker bbox]# docker exec -it web1 /bin/sh/# cat /etc/test.conf PORT=10080/#
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