2、ansible打通主控机与被控机之间的连接。

主控机：安装了ansible的主机，称为主控机。
被控机：一切需要被ansible控制的主机可以称为被控机。
如：在192.168.110.10上安装了ansible，通过ansible工具，在192.168.110.11上部署一个Apache服务。此时，192.168.110.10就是主控机，而192.168.110.11就是被控机。

打通主控机到被控机的通道如下：

• 在/etc/ansible/hosts文件中添加如下内容
  格式：主机IP 远程主机用户名 远程主机用户对应的密码
  [test]
  192.168.110.11 ansible_user=root ansible_ssh_pass=“password”
  ……
  [test]是对远程主机进行分组，一个组下可以有多台主机，当前的test组下就只有一台主机。

• 互信设置
  使用ssh-keygen命令生成密钥，一直回车即可

[root@VM-0-7-centos .ssh]# ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
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:vO1Bag3Svoh8rK4ODpxOOeWdsnsq057oXxuwbsj2g2Q root@VM-0-7-centos
The key's randomart image is:
+---[RSA 2048]----+
|                 |
|                 |
|                 |
|       o         |
|   o  . S .      |
|.E= + .o B       |
|**++ *  = +      |
|=O+==o=o o .     |
|o*X%X+. . .      |
+----[SHA256]-----+

使用ssh-copy-id拷贝密钥到被控机完成互信设置

[root@VM-0-7-centos ~]# ssh-copy-id root@172.27.0.7
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host '172.27.0.7 (172.27.0.7)' can't be established.
ECDSA key fingerprint is SHA256:ettRek/OxGM2fIQPFA5oO77JMaR7ot3ZJs1r9SK8WpQ.
ECDSA key fingerprint is MD5:3d:32:a9:24:2d:db:9a:08:5e:76:b0:29:89:c7:77:f8.
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@172.27.0.7's password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'root@172.27.0.7'"
and check to make sure that only the key(s) you wanted were added.

• 测试互信
  执行如下命令，发现返回结果为 SUCCESS表示成功。ansible all -m ping也是当前的第一条ansible命令。

[root@VM-0-7-centos ~]# ansible all -m ping
172.27.0.12 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python"
    }, 
    "changed": false, 
    "ping": "pong"
}

至此，主控机与被控机的通道已经打通，可以知道，此方法是利用了ssh的互信原理来完成的。当前使用方式打通主控机与被控机的方法效率较低，后面我们会使用playbook的方式完成，一次可以完成成百上千台互信设置。