马哥博客作业第十二周
1、通过Ansible Roles编排实现 httpd 角色的部署
1)、首先创建角色相关文件夹
[root@CentOS7 ~]#tree /roles/
/roles/
└── httpd
├── files
├── handlers
└── tasks
2)、创建角色相关文件(main.yml是tasks的入口文件)
[root@CentOS7 httpd]#cat tasks/main.yml
- include: install.yml
- include: config.yml
- include: modify.yml
- include: index.yml
- include: service.yml
[root@CentOS7 httpd]#cat tasks/install.yml
- name: install httpd
yum: name=httpd
[root@CentOS7 httpd]#cat tasks/config.yml
- name: install configure file
copy: src=httpd.conf dest=/etc/httpd/conf/
[root@CentOS7 httpd]#cat tasks/modify.yml
- name: modify config
lineinfile:
path: /etc/httpd/conf/httpd.conf
regexp: "^Listen"
line: "Listen 8088"
notify: restart service
[root@CentOS7 httpd]#cat tasks/index.yml
- name: web page
copy: src=index.html dest=/var/www/html/
[root@CentOS7 httpd]#cat tasks/service.yml
- name: start service
service: name=httpd state=started enabled=yes
[root@CentOS7 httpd]#cat handlers/main.yml
- name: restart service
service: name=httpd state=restarted
3)、在files目录下准备两个文件
[root@CentOS7 httpd]#ls files/
httpd.conf index.html
4)、目录树结构如下
[root@CentOS7 ~]#tree roles/httpd/
roles/httpd/
├── files
│ ├── httpd.conf
│ └── index.html
├── handlers
│ └── main.yml
└── tasks
├── config.yml
├── index.yml
├── install.yml
├── main.yml
├── modify.yml
└── service.yml
3 directories, 9 files
5)、在playbook中调用角色
[root@CentOS7 ~]#cat role_httpd.yml
---
# role httpd install
- hosts: 10.0.0.211
remote_user: root
gather_facts: no
roles:
- httpd
6)、运行playbook
[root@CentOS7 ~]#ansible-playbook role_httpd.yml
2、简述 MySQL 数据库访问的执行过程。
- 客户端发送一条查询给服务器;
- 服务器先检查查询缓存,如果命中了缓存,则立刻返回存储在缓存中的结果。否则进入下一阶段。
- 服务器端进行SQL解析、预处理,在优化器生成对应的执行计划;
- mysql根据优化器生成的执行计划,调用存储引擎的API来执行查询。
- 将结果返回给客户端。
3、SELECT 语句的完整语法较复杂,但至少包括的部分是 ( A )
A.仅SELECT
B.SELECT ,FROM
C.SELECT ,GROUP
D.SELECT ,INTO
4、一张表的主键个数为 ( C )
A.至多 3 个
B.没有限制
C.至多 1 个
D.至多 2 个