Docker快速入门(十二)Docker多主机管理

Docker多主机管理

之前在一台Centos7上安装了Docker，如果是在多台主机上都安装Docker，用手动安装的方法不光效率低下，而且有可能出错，所以可以使用Docker Machine进行多台主机的Docker安装和管理。
具体安装过程可以参照官方文档https://docs.docker.com/machine/install-machine/.
首先准备两台Centos7的虚拟机（一台IP为192.168.41.133，安装Docker Machine，另一台IP为192.168.41.135），在其中一台机器上安装Docker，安装过程可以参照分享01.
然后下载Docker Machine二进制文件并将其解压缩到PATH。

[root@promote ~]# base=https://github.com/docker/machine/releases/download/v0.14.0 &&
>   curl -L $base/docker-machine-$(uname -s)-$(uname -m) >/tmp/docker-machine &&
>   sudo install /tmp/docker-machine /usr/local/bin/docker-machine
% Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                Dload  Upload   Total   Spent    Left  Speed
100   617    0   617    0     0    583      0 --:--:--  0:00:01 --:--:--   584
100 26.7M  100 26.7M    0     0  1730k      0  0:00:15  0:00:15 --:--:-- 3488k

接着通过显示机器版本来检查安装：

[root@promote ~]# docker-machine version
docker-machine version 0.14.0, build 89b8332

为了更好的体验接着安装bash完成脚本，将脚本保存到/etc/bash_completion.d或 /usr/local/etc/bash_completion.d。

[root@promote ~]# cd /etc/bash_completion.d
[root@promote bash_completion.d]# base=https://raw.githubusercontent.com/docker/machine/v0.14.0
[root@promote bash_completion.d]# for i in docker-machine-prompt.bash docker-machine-wrapper.bash docker-machine.                                                                         bash
> do
>   sudo wget "$base/contrib/completion/bash/${i}" -P /etc/bash_completion.d
> done
--2018-07-11 01:47:47--  https://raw.githubusercontent.com/docker/machine/v0.14.0/contrib/completion/bash/docker-                                                                         machine-prompt.bash
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.40.133
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.40.133|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1469 (1.4K) [text/plain]
Saving to: ‘/etc/bash_completion.d/docker-machine-prompt.bash’
 
100%[=======================================================================>] 1,469       --.-K/s   in 0s
 
2018-07-11 01:47:48 (192 MB/s) - ‘/etc/bash_completion.d/docker-machine-prompt.bash’ saved [1469/1469]
 
--2018-07-11 01:47:48--  https://raw.githubusercontent.com/docker/machine/v0.14.0/contrib/completion/bash/docker-                                                                         machine-wrapper.bash
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.40.133
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.40.133|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1525 (1.5K) [text/plain]
Saving to: ‘/etc/bash_completion.d/docker-machine-wrapper.bash’
 
100%[=======================================================================>] 1,525       --.-K/s   in 0s
 
2018-07-11 01:47:50 (160 MB/s) - ‘/etc/bash_completion.d/docker-machine-wrapper.bash’ saved [1525/1525]
 
--2018-07-11 01:47:50--  https://raw.githubusercontent.com/docker/machine/v0.14.0/contrib/completion/bash/docker-                                                                         machine.bash
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.40.133
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.40.133|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 12205 (12K) [text/plain]
Saving to: ‘/etc/bash_completion.d/docker-machine.bash’
 
100%[=======================================================================>] 12,205      --.-K/s   in 0.02s
 
2018-07-11 01:47:51 (489 KB/s) - ‘/etc/bash_completion.d/docker-machine.bash’ saved [12205/12205]

这样就下载好了脚本。
接着申明环境变量。

[root@promote bash_completion.d]# source /etc/bash_completion.d/docker-machine-prompt.bash 

可以先使用docker-machine ls查看一下当前的machine.

[root@promote ~]# docker-machine ls
NAME   ACTIVE   DRIVER   STATE   URL   SWARM   DOCKER   ERRORS

因为还没有安装Docker所以使用这条命令什么都没有。
接着创建第一台机器，就是另外一台Centos虚拟机（IP：192.168.41.155）.
1.首先需要让这两台Centos可以SSH免密登陆。

[root@promote ~]# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:T6qcnNvYwepsMhGfdvG/Gk+BtzVe2eCLiF0aMAI6wqc root@promote.cache-dns.local
The key's randomart image is:
+---[RSA 2048]----+
|    .            |
|.  . .           |
|..o.  . o     .  |
| .o..  ..o . . .o|
| E   o .So+ + +.o|
|    . +..*.* * + |
|     o .= *.+ o  |
|    o+.O . +.    |
|     =%.o ..o.   |
+----[SHA256]-----+
[root@promote ~]# ssh-copy-id 192.168.41.135
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '192.168.41.135 (192.168.41.135)' can't be established.
ECDSA key fingerprint is SHA256:JqAC8jcLCLobvRy0wzY9VGBNuZU3EydpO8n2fEtQ178.
ECDSA key fingerprint is MD5:5d:26:a1:60:c3:eb:02:e9:97:7a:bb:7a:49:8a:14:0b.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@192.168.41.135's password:
 
Number of key(s) added: 1
 
Now try logging into the machine, with:   "ssh '192.168.41.135'"
and check to make sure that only the key(s) you wanted were added.

2.创建第一个机器
使用docker-machine create命令，因为是Linux，所以driver就用generic,目标地址选项用--generic-ip-address。

[root@promote ~]# docker-machine create --driver generic --generic-ip-address=192.168.41.135 machine1
Creating CA: /root/.docker/machine/certs/ca.pem
Creating client certificate: /root/.docker/machine/certs/cert.pem
Running pre-create checks...
Creating machine...
(machine1) No SSH key specified. Assuming an existing key at the default location.
Waiting for machine to be running, this may take a few minutes...
Detecting operating system of created instance...
Waiting for SSH to be available...
Detecting the provisioner...
Provisioning with centos...
Copying certs to the local machine directory...
Copying certs to the remote machine...
Setting Docker configuration on the remote daemon...
Checking connection to Docker...
Docker is up and running!
To see how to connect your Docker Client to the Docker Engine running on this virtual machine, run: docker-machine env machine1

现在到192.168.41.135上去验证。

[root@promote ~]# docker version
Client:
Version:      18.05.0-ce
API version:  1.37
Go version:   go1.9.5
Git commit:   f150324
Built:        Wed May  9 22:14:54 2018
OS/Arch:      linux/amd64
Experimental: false
Orchestrator: swarm
 
Server:
Engine:
Version:      18.05.0-ce
API version:  1.37 (minimum version 1.12)
Go version:   go1.9.5
Git commit:   f150324
Built:        Wed May  9 22:18:36 2018
OS/Arch:      linux/amd64
Experimental: false

也可以在192.168.41.133上验证。

[root@promote ~]# docker-machine ls
NAME       ACTIVE   DRIVER    STATE     URL                         SWARM   DOCKER        ERRORS
machine1   -        generic   Running   tcp://192.168.41.135:2376           v18.05.0-ce

发现安装完成。
接着我通过192.168.41.133这台主机来使用192.168.41.135主机上的Docker,首先查看访问machine所需要的环境变量。

[root@promote ~]# docker-machine env machine1
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://192.168.41.135:2376"
export DOCKER_CERT_PATH="/root/.docker/machine/machines/machine1"
export DOCKER_MACHINE_NAME="machine1"
# Run this command to configure your shell:
# eval $(docker-machine env machine1)

可以看到倒数第二行：运行此命令来配置你的shell
也就是指运行eval $(docker-machine env machine1)命令配置上面的环境变量进入machine1.
运行之后发现并无变化，是因为一开始我们没有配置shell提示.
接着启用docker-machineshell提示，添加 $(__docker_machine_ps1)到您的PS1设置中~/.bashrc。

[root@promote ~]# PS1='[\u@\h \W$(__docker_machine_ps1)]\$ '
[root@promote ~ [machine1]]#

这时发现shell变了，在当前状态下的所有docker操作都是运行在machine1上的，即192.168.41.135主机上。
如果要切回回来的环境使用unset命令，取消环境变量即可：

[root@promote ~ [machine1]]# unset export DOCKER_TLS_VERIFY
[root@promote ~ [machine1]]# unset DOCKER_HOST
[root@promote ~ [machine1]]# unset DOCKER_CERT_PATH
[root@promote ~ [machine1]]# unset DOCKER_MACHINE_NAME
[root@promote ~]#

发现变回来了。
docker-machine的其他用法可以使用docker-machine --help命令来查看。