Ansible Best Practices Summary

ansible最佳实践总结，参考官方文档Ansible Best Practices。主要介绍了目录结构和部分实践建议。

内容组织：

• 使用“roles”组织特性

• 推荐目录结构 - 1

production                # inventory file for production servers
staging                   # inventory file for staging environment

group_vars/
   group1                 # here we assign variables to particular groups
   group2                 # ""
host_vars/
   hostname1              # if systems need specific variables, put them here
   hostname2              # ""

library/                  # if any custom modules, put them here (optional)
filter_plugins/           # if any custom filter plugins, put them here (optional)

site.yml                  # master playbook
webservers.yml            # playbook for webserver tier
dbservers.yml             # playbook for dbserver tier

roles/
    common/               # this hierarchy represents a "role"
        tasks/            #
            main.yml      #  <-- tasks file can include smaller files if warranted
        handlers/         #
            main.yml      #  <-- handlers file
        templates/        #  <-- files for use with the template resource
            ntp.conf.j2   #  <------- templates end in .j2
        files/            #
            bar.txt       #  <-- files for use with the copy resource
            foo.sh        #  <-- script files for use with the script resource
        vars/             #
            main.yml      #  <-- variables associated with this role
        defaults/         #
            main.yml      #  <-- default lower priority variables for this role
        meta/             #
            main.yml      #  <-- role dependencies
        library/          # roles can also include custom modules
        lookup_plugins/   # or other types of plugins, like lookup in this case

    webtier/              # same kind of structure as "common" was above, done for the webtier role
    monitoring/           # ""
    fooapp/               # ""

• 推荐目录结构 - 2
  • 适合多环境，环境之间变量少公用
  • 文件数较多，难维护

inventories/
   production/
      hosts               # inventory file for production servers
      group_vars/
         group1           # here we assign variables to particular groups
         group2           # ""
      host_vars/
         hostname1        # if systems need specific variables, put them here
         hostname2        # ""

   staging/
      hosts               # inventory file for staging environment
      group_vars/
         group1           # here we assign variables to particular groups
         group2           # ""
      host_vars/
         stagehost1       # if systems need specific variables, put them here
         stagehost2       # ""

library/
filter_plugins/

site.yml
webservers.yml
dbservers.yml

roles/
    common/
    webtier/
    monitoring/
    fooapp/

• 使用动态的Inventory
• 建议根据host的用途(角色)，以及所在位置、机房来定义groups

# file: production

[atlanta-webservers]
www-atl-1.example.com
www-atl-2.example.com

[boston-webservers]
www-bos-1.example.com
www-bos-2.example.com

[atlanta-dbservers]
db-atl-1.example.com
db-atl-2.example.com

[boston-dbservers]
db-bos-1.example.com

# webservers in all geos
[webservers:children]
atlanta-webservers
boston-webservers

# dbservers in all geos
[dbservers:children]
atlanta-dbservers
boston-dbservers

# everything in the atlanta geo
[atlanta:children]
atlanta-webservers
atlanta-dbservers

# everything in the boston geo
[boston:children]
boston-webservers
boston-dbservers

• 使用 group_vars / host_vars 来设定变量

# 使用上一条的示例

---
# file: group_vars/atlanta
ntp: ntp-atlanta.example.com
backup: backup-atlanta.example.com

---
# file: group_vars/webservers
apacheMaxRequestsPerChild: 3000
apacheMaxClients: 900

---
# file: group_vars/all
ntp: ntp-boston.example.com
backup: backup-boston.example.com

---
# file: host_vars/db-bos-1.example.com
foo_agent_port: 86
bar_agent_port: 99

• 顶层的playbook只包含Role，非常简短

  • site.yml 中定义基础结构，只包含别的playbooks

  ---
  # file: site.yml
  - include: webservers.yml
  - include: dbservers.yml
  

  • playbook中只包含Roles

  ---
  # file: webservers.yml
  - hosts: webservers
    roles:
      - common
      - webtier
  

• 使用 Role 组织 Task 和 Handler

其他

• 多环境使用策略：不同环境（生产或测试）使用不同的inventory配置文件，使用 -i 来选择对应的配置
• 标明 modules的状态，不管 state 是 present 或 absent
• 对不同角色的host进行分组(groups)
• 鼓励使用空格来分隔内容,用 ‘#’ 来写注释
• 给 Tasks 命名或者增加描述(name)
• 不要试图一次性使用 Ansible 的所有的特性，仅仅使用对你有用的即可，保持简洁简单。
• 使用版本控制系统来管理ansible脚本