Centos7 Docker基本特性入门实践-2
来源:互联网 发布:双色球排列组合软件 编辑:程序博客网 时间:2024/06/13 14:36
续CentOS 7 Docker基本特性入门实践-1
构建Image
通过创建Dockerfile可以构建Image,Docker会从一个Dockerfile中读取一系列指令来构建Image。一个Dockerfile是一个文本文件,它包含了一组能够运行的命令行,这些命令行就组装成了一个Docker Image。
下面,我们看一下前面提到的名称为hello-world的Image是如何构建,可以在Github上看到该Image的代码,链接在这里:https://github.com/docker-library/hello-world。
hello-world一定对应一个Dockerfile,内容如下所示:
1
FROM scratch
2
COPY hello /
3
CMD [
"/hello"
]
上面这3条命令,就对应着hello-world这个Image:
第一行,FROM命令:是从一个已知的基础Image来构建新的Image,这里scratch是一个显式指定的空Image;
第二行,COPY命令:是将指定的新文件或目录,拷贝到Container中指定的目录下面,这里讲hello这个可执行文件复制到Container中的根路径/下面;
第三行,CMD命令:是运行指定的命令行,包含指定的命令名称、参数列表
可见,上面的hello可执行文件是已经构编译好的文件,它是从一个C程序文件(Github链接:https://github.com/docker-library/hello-world/blob/master/hello.c)编译而来的,源码文件hello.c内容如下所示:
01
#include <sys/syscall.h>
02
03
#ifndef DOCKER_IMAGE
04
#define DOCKER_IMAGE "hello-world"
05
#endif
06
07
#ifndef DOCKER_GREETING
08
#define DOCKER_GREETING "Hello from Docker!"
09
#endif
10
11
const
char
message[] =
12
"\n"
13
DOCKER_GREETING
"\n"
14
"This message shows that your installation appears to be working correctly.\n"
15
"\n"
16
"To generate this message, Docker took the following steps:\n"
17
" 1. The Docker client contacted the Docker daemon.\n"
18
" 2. The Docker daemon pulled the \""
DOCKER_IMAGE
"\" image from the Docker Hub.\n"
19
" 3. The Docker daemon created a new container from that image which runs the\n"
20
" executable that produces the output you are currently reading.\n"
21
" 4. The Docker daemon streamed that output to the Docker client, which sent it\n"
22
" to your terminal.\n"
23
"\n"
24
"To try something more ambitious, you can run an Ubuntu container with:\n"
25
" $ docker run -it ubuntu bash\n"
26
"\n"
27
"Share images, automate workflows, and more with a free Docker ID:\n"
28
" https://cloud.docker.com/\n"
29
"\n"
30
"For more examples and ideas, visit:\n"
31
" https://docs.docker.com/engine/userguide/\n"
32
"\n"
;
33
34
void
_start() {
35
//write(1, message, sizeof(message) - 1);
36
syscall(SYS_write, 1, message,
sizeof
(message) - 1);
37
38
//_exit(0);
39
syscall(SYS_exit, 0);
40
}
编译生成可执行文件hello,然后可以使用Docker的build命令来构建生成Image:
1
docker build -t hello-world
现在,hello-world是如何构建Image的就已经非常清楚了。下面,我们通过参考官网的用户指南,编写一个Dockerfile来制作一个Image,了解如何实现自己的应用:
- 编写Dockerfile
首先,创建一个单独的目录来存放我们将要构建的Dockerfile文件:
1
mkdir
mydockerbuild
2
cd
mydockerbuild
3
vi
Dockerfile
在Dockerfile中输入如下内容:
1
FROM docker/whalesay:latest
2
RUN apt-get -y update && apt-get
install
-y fortunes
3
CMD /usr/games/fortune -a | cowsay
上面FROM命令表示,Docker基于该docker/whalesay:latest来构建新的Image,这个Image在Docker Hub上,链接在这里:https://hub.docker.com/r/docker/whalesay/,对应的源码可以看Github:https://github.com/docker/whalesay。RUN命令行表示安装fortunes程序包,最后的CMD命令指示将运行/usr/games/fortune命令。
- 构建Image
保存上述3行命令到文件中,在当前mydockerbuild目录中执行构建Image的命令:
1
docker build -t docker-whale .
构建过程,输出信息如下:
01
Sending build context to Docker daemon 2.048 kB
02
Step 1/3 : FROM docker/whalesay:latest
03
---> 6b362a9f73eb
04
Step 2/3 : RUN apt-get -y update && apt-get install -y fortunes
05
---> Running in bfddc2134d23
06
Ign http://archive.ubuntu.com trusty InRelease
07
Get:1 http://archive.ubuntu.com trusty-updates InRelease [65.9 kB]
08
Get:2 http://archive.ubuntu.com trusty-security InRelease [65.9 kB]
09
Hit http://archive.ubuntu.com trusty Release.gpg
10
Get:3 http://archive.ubuntu.com trusty-updates/main Sources [485 kB]
11
Get:4 http://archive.ubuntu.com trusty-updates/restricted Sources [5957 B]
12
Get:5 http://archive.ubuntu.com trusty-updates/universe Sources [220 kB]
13
Get:6 http://archive.ubuntu.com trusty-updates/main amd64 Packages [1197 kB]
14
Get:7 http://archive.ubuntu.com trusty-updates/restricted amd64 Packages [20.4 kB]
15
Get:8 http://archive.ubuntu.com trusty-updates/universe amd64 Packages [516 kB]
16
Get:9 http://archive.ubuntu.com trusty-security/main Sources [160 kB]
17
Get:10 http://archive.ubuntu.com trusty-security/restricted Sources [4667 B]
18
Get:11 http://archive.ubuntu.com trusty-security/universe Sources [59.4 kB]
19
Get:12 http://archive.ubuntu.com trusty-security/main amd64 Packages [730 kB]
20
Get:13 http://archive.ubuntu.com trusty-security/restricted amd64 Packages [17.0 kB]
21
Get:14 http://archive.ubuntu.com trusty-security/universe amd64 Packages [199 kB]
22
Hit http://archive.ubuntu.com trusty Release
23
Hit http://archive.ubuntu.com trusty/main Sources
24
Hit http://archive.ubuntu.com trusty/restricted Sources
25
Hit http://archive.ubuntu.com trusty/universe Sources
26
Hit http://archive.ubuntu.com trusty/main amd64 Packages
27
Hit http://archive.ubuntu.com trusty/restricted amd64 Packages
28
Hit http://archive.ubuntu.com trusty/universe amd64 Packages
29
Fetched 3745 kB in 55s (67.1 kB/s)
30
Reading package lists...
31
Reading package lists...
32
Building dependency tree...
33
Reading state information...
34
The following extra packages will be installed:
35
fortune-mod fortunes-min librecode0
36
Suggested packages:
37
x11-utils bsdmainutils
38
The following NEW packages will be installed:
39
fortune-mod fortunes fortunes-min librecode0
40
0 upgraded, 4 newly installed, 0 to remove and 92 not upgraded.
41
Need to get 1961 kB of archives.
42
After this operation, 4817 kB of additional disk space will be used.
43
Get:1 http://archive.ubuntu.com/ubuntu/ trusty/main librecode0 amd64 3.6-21 [771 kB]
44
Get:2 http://archive.ubuntu.com/ubuntu/ trusty/universe fortune-mod amd64 1:1.99.1-7 [39.5 kB]
45
Get:3 http://archive.ubuntu.com/ubuntu/ trusty/universe fortunes-min all 1:1.99.1-7 [61.8 kB]
46
Get:4 http://archive.ubuntu.com/ubuntu/ trusty/universe fortunes all 1:1.99.1-7 [1089 kB]
47
debconf: unable to initialize frontend: Dialog
48
debconf: (TERM is not set, so the dialog frontend is not usable.)
49
debconf: falling back to frontend: Readline
50
debconf: unable to initialize frontend: Readline
51
debconf: (This frontend requires a controlling tty.)
52
debconf: falling back to frontend: Teletype
53
dpkg-preconfigure: unable to re-open stdin:
54
Fetched 1961 kB in 5s (340 kB/s)
55
Selecting previously unselected package librecode0:amd64.
56
(Reading database ... 13116 files and directories currently installed.)
57
Preparing to unpack .../librecode0_3.6-21_amd64.deb ...
58
Unpacking librecode0:amd64 (3.6-21) ...
59
Selecting previously unselected package fortune-mod.
60
Preparing to unpack .../fortune-mod_1%3a1.99.1-7_amd64.deb ...
61
Unpacking fortune-mod (1:1.99.1-7) ...
62
Selecting previously unselected package fortunes-min.
63
Preparing to unpack .../fortunes-min_1%3a1.99.1-7_all.deb ...
64
Unpacking fortunes-min (1:1.99.1-7) ...
65
Selecting previously unselected package fortunes.
66
Preparing to unpack .../fortunes_1%3a1.99.1-7_all.deb ...
67
Unpacking fortunes (1:1.99.1-7) ...
68
Setting up librecode0:amd64 (3.6-21) ...
69
Setting up fortune-mod (1:1.99.1-7) ...
70
Setting up fortunes-min (1:1.99.1-7) ...
71
Setting up fortunes (1:1.99.1-7) ...
72
Processing triggers for libc-bin (2.19-0ubuntu6.6) ...
73
---> 98403143b081
74
Removing intermediate container bfddc2134d23
75
Step 3/3 : CMD /usr/games/fortune -a | cowsay
76
---> Running in 8831a7231adc
77
---> 08d234c4ee26
78
Removing intermediate container 8831a7231adc
79
Successfully built 08d234c4ee26
或者,可以通过-f选项,直接指定Dockerfile文件的绝对路径,构建命令如下所示:
1
docker build -f ~/mydockerbuild/Dockerfile -t docker-whale .
这样我们自己的Image就构建好了,名称为docker-whale。下面,看下构建我们这个Image的基本流程流程:
- Docker检查确保当前Dockerfile中是否有需要build的内容
- Docker检查是否存在whalesay这个Image
- Docker会启动一个临时的容器6b362a9f73eb,来运行whalesay这个image。在这个临时的Container中,Docker会执行RUN这行命令,安装fortune程序包
- 一个新的中间container被创建8831a7231adc,在Dockerfile中增加了一个CMD层(Layer),对应一个Container,然后中间container8831a7231adc被删除
我们在构建一个Image时,会自动下载依赖的Docker Image,其实也可以预先下载对应的Image,使用类似下面的命令:
1
docker pull mysql:5.5
这样就可以下载MySQL 5.5的Image到本地。
- 查看构建的Image
查看当前image列表,其中包含我们刚刚构建好的Image,执行docker images命令,结果如下所示:
1
REPOSITORY TAG IMAGE ID CREATED SIZE
2
docker-whale latest 08d234c4ee26 9 minutes ago 256 MB
3
ubuntu latest f49eec89601e 5 weeks ago 129 MB
4
hello-world latest 48b5124b2768 6 weeks ago 1.84 kB
5
docker/whalesay latest 6b362a9f73eb 21 months ago 247 MB
第一个docker-whale,就是我们自己创建的。
- 启动Docker Container
接着,基于我们已经构建好的Image,在Docker Container中运行这个应用,执行命令:
1
docker run docker-whale
运行结果,如下所示:
01
______________________________
02
/ IBM: \
03
| |
04
| I've Been Moved |
05
| |
06
| Idiots Become Managers |
07
| |
08
| Idiots Buy More |
09
| |
10
| Impossible to Buy Machine |
11
| |
12
| Incredibly Big Machine |
13
| |
14
| Industry's Biggest Mistake |
15
| |
16
| International Brotherhood of |
17
| Mercenaries |
18
| |
19
| It Boggles the Mind |
20
| |
21
| It's Better Manually |
22
| |
23
\ Itty-Bitty Machines /
24
------------------------------
25
\
26
\
27
\
28
## .
29
## ## ## ==
30
## ## ## ## ===
31
/""""""""""""""""___/ ===
32
~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ / ===- ~~~
33
\______ o __/
34
\ \ __/
35
\____\______/
另外,我们可以进入到Docker Hub:https://hub.docker.com,创建一个自己的账号,然后创建自己的Image,当然也可以找到各种免费共享的Image,可以基于这些Image来构建自己的Image。Docker Hub页面,如下所示:
下面是一个例子,可以在启动Docker Container时,通过命令行直接向Container内部应用传递参数值,命令行如下所示:
1
docker run docker/whalesay cowsay boo
2
docker run docker/whalesay cowsay boo-boo
可以看到,输出的内容根据启动Container传递的参数值而变化。
- 查看Docker Container
查看当前主机上所有状态的Docker Container,可以执行如下命令(下面的命令都是等价的):
1
docker
ps
-a
2
docker container
ps
-a
3
docker container
ls
-a
示例结果,如下所示:
1
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
2
5ab157767bbd training/postgres "su postgres -c '/..." 6 seconds ago Up 5 seconds 5432/tcp pgdb
3
da91889d6313 training/postgres "su postgres -c '/..." 49 seconds ago Up 2 seconds 5432/tcp webappdb
4
5d86616e9a1d docker-whale "/bin/sh -c '/usr/..." 24 minutes ago Exited (0) 7 seconds ago elastic_mcnulty
5
abec6410bcac docker/whalesay "cowsay boo" 27 minutes ago Exited (0) 27 minutes ago upbeat_edison
6
72d0b2bb5d6a training/postgres "su postgres -c '/..." 4 hours ago Up 4 hours 5432/tcp db
7
fc9b0bb6ae8e ubuntu "/bin/bash" 4 hours ago Up 4 hours networktest
8
fc9b0bb6ae8e ubuntu "/bin/bash" 7 days ago Exited (255) 3 days ago networktest
查看当前运行中的Container,可以执行如下命令查看(下面的命令都是等价的):
1
docker
ps
2
docker container
ps
3
docker container
ls
Docker网络
Docker支持Container之间通过网络互连,提供了两种网络Driver,分别为Bridge和Overlay,我们也可以实现自己的网络Driver插件来管理我们的Docker Container网络。目前,有很多Docker网络的解决方案,如Flannel、Weave、Pipework、libnetwork等,感兴趣可以深入研究一下。
在安装Docker Engine之后,会包含三个默认的网络,可以通过如下命令查看当前所有的网络:
1
docker network
ls
结果如下所示:
1
NETWORK ID NAME DRIVER SCOPE
2
b92d9ca4d992 bridge bridge local
3
6d33880bf521 host host local
4
a200b158f39c none null local
名称为host的网络,表示宿主机的网络,如果启动Docker Container指定该网络,则Container与宿主机使用相同的Network Namespace,也就是启动的Container的网络会使用宿主机的网卡、IP、端口。
在启动Docker Container时,如果我们没有显式指定网络名称,Docker会使用默认的bridge网络。这种网络模式下,Docker会为Container创建一个独立于宿主机的Network Namespace,并使用独立的IP段,Container连接到一个虚拟网桥上,默认是docker0网桥。虚拟网桥与交换机的工作方式类似,启动的Docker Container连接到虚拟网桥上,这就构成了一个二层网络。
为了更加直观说明,我们参考了网上的一个Docker网络的结构图,如下图所示:
下面,通过Docker网络功能,看如何将Container网络连接起来。
- 创建Docker网络
创建一个Docker网络,名称为my-bridge-network,执行如下命令:
1
docker network create -d bridge my-bridge-network
创建的结果,输出了新建Docker网络的ID,如下所示:
1
fc19452525e5d2f5f1fc109656f0385bf2f268b47788353c3d9ee672da31b33a
上面fc19452525e5d2f5f1fc109656f0385bf2f268b47788353c3d9ee672da31b33a就是新创建网络my-bridge-network的ID,可以通过如下命令查看:
1
docker network
ls
当前主机上存在的所有Docker网络信息,如下所示:
1
NETWORK ID NAME DRIVER SCOPE
2
b92d9ca4d992 bridge bridge local
3
6d33880bf521 host host local
4
fc19452525e5 my-bridge-network bridge local
5
a200b158f39c none null local
- 查看一个Docker网络
查看一个Docker网络的详细信息,查看默认的bridge网络,可以执行如下命令:
1
docker network inspect bridge
执行结果,如下所示:
01
[
02
{
03
"Name": "bridge",
04
"Id": "2872de41fddddc22420eecad253107e09a305f3512ade31d4172d3b80723d8b6",
05
"Created": "2017-03-05T21:46:12.413438219+08:00",
06
"Scope": "local",
07
"Driver": "bridge",
08
"EnableIPv6": false,
09
"IPAM": {
10
"Driver": "default",
11
"Options": null,
12
"Config": [
13
{
14
"Subnet": "172.17.0.0/16",
15
"Gateway": "172.17.0.1"
16
}
17
]
18
},
19
"Internal": false,
20
"Attachable": false,
21
"Containers": {
22
"5ab157767bbd991401c351cfb452d663f5cd93dd1edc56767372095a5c2e7f73": {
23
"Name": "pgdb",
24
"EndpointID": "e0368c3219bcafea7c2839b7ede628fa67ad0a5350d150fdf55a4aa88c01c480",
25
"MacAddress": "02:42:ac:11:00:02",
26
"IPv4Address": "172.17.0.2/16",
27
"IPv6Address": ""
28
},
29
"da91889d63139019bbdcc6266704fb21e0a1800d0ae63b3448e65d1e17ef7368": {
30
"Name": "webappdb",
31
"EndpointID": "422ab05dd2cbb55266964b31f0dd9292688f1459e3a687662d1b119875d4ce44",
32
"MacAddress": "02:42:ac:11:00:03",
33
"IPv4Address": "172.17.0.3/16",
34
"IPv6Address": ""
35
}
36
},
37
"Options": {
38
"com.docker.network.bridge.default_bridge": "true",
39
"com.docker.network.bridge.enable_icc": "true",
40
"com.docker.network.bridge.enable_ip_masquerade": "true",
41
"com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
42
"com.docker.network.bridge.name": "docker0",
43
"com.docker.network.driver.mtu": "1500"
44
},
45
"Labels": {}
46
}
47
]
通过上面结果信息可以看到,当前bridge网络的ID为2872de41fddddc22420eecad253107e09a305f3512ade31d4172d3b80723d8b6,在该Docker网络内部运行中的Container有2个,分别为pgdb和webapp,他们在Container内部的IP地址分别为172.17.0.2和172.17.0.3,因为在同一个bridge网络中,所以共享相同的IP地址段。
或者,我们也可以格式化输出某个Container所在网络的设置,执行如下命令:
1
docker inspect --
format
=
'{{json .NetworkSettings.Networks}}'
pgdb
输出结果如下所示(结果格式化过):
01
{
02
"bridge": {
03
"IPAMConfig": null,
04
"Links": null,
05
"Aliases": null,
06
"NetworkID": "2872de41fddddc22420eecad253107e09a305f3512ade31d4172d3b80723d8b6",
07
"EndpointID": "e0368c3219bcafea7c2839b7ede628fa67ad0a5350d150fdf55a4aa88c01c480",
08
"Gateway": "172.17.0.1",
09
"IPAddress": "172.17.0.2",
10
"IPPrefixLen": 16,
11
"IPv6Gateway": "",
12
"GlobalIPv6Address": "",
13
"GlobalIPv6PrefixLen": 0,
14
"MacAddress": "02:42:ac:11:00:02"
15
}
16
}
可见和上面的命令类似,能输出Docker网络bridge的基本信息。
转载至:http://shiyanjun.cn/archives/1608.html
- Centos7 Docker基本特性入门实践-2
- Centos7 Docker基本特性入门实践-3
- CentOS 7 Docker基本特性入门实践-1
- Docker Swarm架构、特性与基本实践
- Docker Swarm架构、特性与基本实践
- CentOS 7 开源的应用容器引擎Docker基本特性入门实践
- Docker入门实践(三) 基本操作
- Docker实践快速入门
- docker实践入门之一
- docker入门实践
- Docker 入门实践
- Docker实践快速入门
- Docker 入门实践
- 【docker入门】centos7下安装docker
- 基于Docker Swarm官网文档总结其架构、特性与基本实践
- Docker入门实践(一) 理解Docker
- centos7.2 docker安装
- Docker 基础入门与实践
- 用omnetpp仿真dsr协议
- 列表的两端对齐布局
- jsp概述
- AdroidStudio上传SVN忽略文件
- comma.ai代码及实践纪实
- Centos7 Docker基本特性入门实践-2
- linux
- springMVC +easyUI + hibernate 集合kindeditor富文本编辑
- jQuery滚动插件Sly.js 滑动最后几个元素不在一行 滑动显示不完整
- AIDL 入门
- 使用Intellij ide在Azure上搭建JavaWeb项目
- Unity编辑器扩展
- pure seq2seq
- ORA-12005: may not schedule automatic refresh for times in the past