要结合ansible事实变量和主机清单变量

botang

1. 生成主机文件
   
2. 将一个初始模板文件从 http://classroom.example.com/content/hosts.j2 下载到/home/student/ansible
   
3. 完成该模板,以便用它生成以下文件:针对每个清单主机包含一行内容,其格式与/etc/hosts 相同
   
4. 创建名为/home/student/ansible/hosts.yml 的 playbook,它将使用此模板在 dev 主机组中的主机上生成文件/etc/myhosts 。
   
5. 该 playbook 运行后, dev 主机组中主机上的文件/etc/myhosts 应针对每个受管主机包含一行内容:
   
6. 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
   
7. ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
   
8. 172.25.250.10 servera.lab.example.com servera
   
9. 172.25.250.11 serverb.lab.example.com serverb
   
10. 172.25.250.12 serverc.lab.example.com serverc
    
11. 172.25.250.13 serverd.lab.example.com serverd
    
12. 注:清单主机名称的显示顺序不重要。

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不正确的做法（只用事实变量）：

1. [student@workstation ansible]$ cat hosts.j2

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127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

{% for host in groups['all'] %}
{{ ansible_default_ipv4['address'] }} {{ ansible_fqdn }} {{ ansible_hostname }}
{% endfor %}


hosts.yml:

1. ---
   
2. - name: Create myhosts
   
3.   hosts: dev
   
4.   tasks:
   
5.   - name: Create myhosts
   
6.     template:
   
7.       src: hosts.j2
   
8.       dest: /etc/myhosts
   

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1. [student@workstation ansible]$ ansible  dev -m shell -a 'cat /etc/myhosts'

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servera | CHANGED | rc=0 >>
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

172.25.250.10 servera.lab.example.com servera
172.25.250.10 servera.lab.example.com servera
172.25.250.10 servera.lab.example.com servera
172.25.250.10 servera.lab.example.com servera


结合了静态的清单和动态的事实（可以实现在A机上看到B机的实际情况，A机和B机都是受管节点，他们之间互相“检举”）：

https://www.botangdb.com/forum.php?mod=viewthread&tid=1491&page=1&extra=#pid2549

host.j2:

1. 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
   
2. ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
   
3. 
   
4. {% for host in groups['all'] %}
   
5. {{ hostvars[host]['ansible_default_ipv4']['address'] }} {{ hostvars[host]['ansible_fqdn'] }} {{ hostvars[host]['ansible_hostname'] }}
   
6. {% endfor %}
   
7. 
   

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hosts.yml:

1. ---
   
2. - name: Create myhosts
   
3.   hosts: all
   
4.   tasks:
   
5.   - name: Create myhosts
   
6.     template:
   
7.       src: hosts.j2
   
8.       dest: /etc/myhosts
   
9.     when:
   
10.       ansible_hostname in groups['dev']
    

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