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26_尚硅谷_Docker_DockerFile案例-CMD-ENTRYPOINT命令案例(CMD与ENTRYPOINT的区别)

发布时间：2022-11-13 13:53:01编辑：雪饮阅读（）

step1

curl命令 –i用于显示本次请求的有关头信息 –v用于显示本次请求的全过程。

如下面绿色部分就是v参数的输出，-i有包含请求的头信息，但是由于默认好像也有显示请求体，所以夹杂在一起了。

[root@localhost mydocker]# curl -iv www.baidu.com

* About to connect() to www.baidu.com port 80 (#0)

* Trying 163.177.151.110...

* Connected to www.baidu.com (163.177.151.110) port 80 (#0)

> GET / HTTP/1.1

> User-Agent: curl/7.29.0

> Host: www.baidu.com

> Accept: */*

< HTTP/1.1 200 OK

HTTP/1.1 200 OK

< Accept-Ranges: bytes

Accept-Ranges: bytes

< Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform

Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform

< Connection: keep-alive

Connection: keep-alive

< Content-Length: 2381

Content-Length: 2381

< Content-Type: text/html

Content-Type: text/html

< Date: Sun, 13 Nov 2022 05:13:57 GMT

Date: Sun, 13 Nov 2022 05:13:57 GMT

< Etag: "588604dc-94d"

Etag: "588604dc-94d"

< Last-Modified: Mon, 23 Jan 2017 13:27:56 GMT

Last-Modified: Mon, 23 Jan 2017 13:27:56 GMT

< Pragma: no-cache

Pragma: no-cache

< Server: bfe/1.0.8.18

Server: bfe/1.0.8.18

< Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/

Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/

<!DOCTYPE html>

<html> <head><meta http-equiv=content-type content=text/html;charset=utf-8><meta http-equiv=X-UA-Compatible content=IE=Edge><meta content=always name=referrer><link rel=stylesheet type=text/css href=http://s1.bdstatic.com/r/www/cache/bdorz/baidu.min.css><title>百度一下，你就知道</title></head> <body link=#0000cc> <div id=wrapper> <div id=head> <div class=head_wrapper> <div class=s_form> <div class=s_form_wrapper> <div id=lg> <img hidefocus=true src=//www.baidu.com/img/bd_logo1.png width=270 height=129> </div> <form id=form name=f action=//www.baidu.com/s class=fm> <input type=hidden name=bdorz_come value=1> <input type=hidden name=ie value=utf-8> <input type=hidden name=f value=8> <input type=hidden name=rsv_bp value=1> <input type=hidden name=rsv_idx value=1> <input type=hidden name=tn value=baidu><span class="bg s_ipt_wr"><input id=kw name=wd class=s_ipt value maxlength=255 autocomplete=off autofocus></span><span class="bg s_btn_wr"><input type=submit id=su value=百度一下 class="bg s_btn"></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class=mnav>新闻</a> <a href=http://www.hao123.com name=tj_trhao123 class=mnav>hao123</a> <a href=http://map.baidu.com name=tj_trmap class=mnav>地图</a> <a href=http://v.baidu.com name=tj_trvideo class=mnav>视频</a> <a href=http://tieba.baidu.com name=tj_trtieba class=mnav>贴吧</a> <noscript> <a href=http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2f%3fbdorz_come%3d1 name=tj_login class=lb>登录</a> </noscript> <script>document.write('<a href="http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u='+ encodeURIComponent(window.location.href+ (window.location.search === "" ? "?" : "&")+ "bdorz_come=1")+ '" name="tj_login" class="lb">登录</a>');</script> <a href=//www.baidu.com/more/ name=tj_briicon class=bri style="display: block;">更多产品</a> </div> </div> </div> <div id=ftCon> <div id=ftConw> <p id=lh> <a href=http://home.baidu.com>关于百度</a> <a href=http://ir.baidu.com>About Baidu</a> </p> <p id=cp>©2017 Baidu <a href=http://www.baidu.com/duty/>使用百度前必读</a>  <a href=http://jianyi.baidu.com/ class=cp-feedback>意见反馈</a> 京ICP证030173号  <img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html>

* Connection #0 to host www.baidu.com left intact

step2

编写基于cmd实现的一个curl查看百度首页的镜像，要求要有curl的-i和-v的功能，且-v的功能是不能在DockerFile里面写死

实现方式1

假定实现如：

[root@localhost mydocker]# cat DockerFile3

from centos:centos7

run yum install -y curl

cmd ["curl","-i","http://ip.cn"]

对于cmd中的中括号我的理解就是命令和参数一次性放进去，就像我们命令和参数一般是用空格分隔的，他这里则以用这种类似数组的形式存放而已。

构建镜像

docker build -f /root/mydocker/DockerFile3 -t mycentos73 .

运行镜像

[root@localhost mydocker]# docker run mycentos73

% Total % Received % Xferd Average Speed Time Time Time Current

Dload Upload Total Spent Left Speed

100 2381 100 2381 0 0 12079 0 --:--:-- --:--:-- --:--:-- 12086

HTTP/1.1 200 OK

Accept-Ranges: bytes

Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform

Connection: keep-alive

Content-Length: 2381

Content-Type: text/html

Date: Sun, 13 Nov 2022 05:42:40 GMT

Etag: "588604cf-94d"

Last-Modified: Mon, 23 Jan 2017 13:27:43 GMT

Pragma: no-cache

Server: bfe/1.0.8.18

Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/

<!DOCTYPE html>

运行镜像并带上v参数

[root@localhost mydocker]# docker run mycentos73 -v

docker: Error response from daemon: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: exec: "-v": executable file not found in $PATH: unknown.

ERRO[0000] error waiting for container: context canceled

[root@localhost mydocker]# docker run mycentos73 v

docker: Error response from daemon: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: exec: "v": executable file not found in $PATH: unknown.

可见无论是v还是-v都出现了问题

实现方式2

entrypoint实现方式编写DockerFile

[root@localhost mydocker]# cat DockerFile4

from centos:centos7

run yum install -y curl

entrypoint ["curl","-i","www.baidu.com"]

镜像构建

docker build -f /root/mydocker/DockerFile4 -t mycentos74 .

直接运行

[root@localhost mydocker]# docker run mycentos74

% Total % Received % Xferd Average Speed Time Time Time Current

Dload Upload Total Spent Left Speed

100 2381 100 2381 0 0 14080 0 --:--:-- --:--:-- --:--:-- 14172

HTTP/1.1 200 OK

Accept-Ranges: bytes

Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform

Connection: keep-alive

Content-Length: 2381

Content-Type: text/html

Date: Sun, 13 Nov 2022 05:47:26 GMT

Etag: "588604dd-94d"

Last-Modified: Mon, 23 Jan 2017 13:27:57 GMT

Pragma: no-cache

Server: bfe/1.0.8.18

Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/

<!DOCTYPE html>

带上v参数

[root@localhost mydocker]# docker run mycentos74 v

% Total % Received % Xferd Average Speed Time Time Time Current

Dload Upload Total Spent Left Speed

100 2381 100 2381 0 0 10779 0 --:--:-- --:--:-- --:--:-- 10822

HTTP/1.1 200 OK

Accept-Ranges: bytes

Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform

Connection: keep-alive

Content-Length: 2381

Content-Type: text/html

Date: Sun, 13 Nov 2022 05:47:56 GMT

Etag: "588604dd-94d"

Last-Modified: Mon, 23 Jan 2017 13:27:57 GMT

Pragma: no-cache

Server: bfe/1.0.8.18

Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/

<!DOCTYPE html>

0 0 0 0 0 0 0 0 --:--:-- 0:00:18 --:--:-- 0curl: (6) Could not resolve host: v; Unknown error

有点小报错。

带上-v参数

[root@localhost mydocker]# docker run mycentos74 -v

% Total % Received % Xferd Average Speed Time Time Time Current

Dload Upload Total Spent Left Speed

0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* About to connect() to www.baidu.com port 80 (#0)

* Trying 163.177.151.109...

* Connected to www.baidu.com (163.177.151.109) port 80 (#0)

> GET / HTTP/1.1

> User-Agent: curl/7.29.0

> Host: www.baidu.com

> Accept: */*

< HTTP/1.1 200 OK

< Accept-Ranges: bytes

< Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform

< Connection: keep-alive

< Content-Length: 2381

< Content-Type: text/html

< Date: Sun, 13 Nov 2022 05:48:22 GMT

< Etag: "588604dd-94d"

< Last-Modified: Mon, 23 Jan 2017 13:27:57 GMT

< Pragma: no-cache

< Server: bfe/1.0.8.18

< Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/

{ [data not shown]

100 2381 100 2381 0 0 22552 0 --:--:-- --:--:-- --:--:-- 22676

* Connection #0 to host www.baidu.com left intact

HTTP/1.1 200 OK

Accept-Ranges: bytes

Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform

Connection: keep-alive

Content-Length: 2381

Content-Type: text/html

Date: Sun, 13 Nov 2022 05:48:22 GMT

Etag: "588604dd-94d"

Last-Modified: Mon, 23 Jan 2017 13:27:57 GMT

Pragma: no-cache

Server: bfe/1.0.8.18

Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/

<!DOCTYPE html>

没有报错

可见，v可能docker的参数，与容器里面entrypoint的参数冲突了，所以就不简写，用-v了。

关键字词：Docker,DockerFile,案例,CMD,ENTRYPOINT,命令

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