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自动化运维工具Ansible(10)Jinja2模板

一、Ansible Jinja2模板背景介绍

目前Nginx的配置文件在所有的服务器上都是相同的,但能根据每一台服务器的性能去定制服务的启动进程。同时定制每一台Nginx服务的响应头,以便于当某台服务出现问题时能快速定位到具体的服务器。要做这样的定制势必会导致一个问题,Nginx 在每台物理服务器上的配置文件都不一样,这样的配置文件如何管理呢?再使用copy 模块去做管理显然已经不合适。此时使用Ansible 提供的另一个模板(template) 功能解决问题。


二、JinJa2 模板

Jinja2是基于Python书写的模板引擎。功能比较类似于PHP的smarty模板。

  • jinja2 文件以 `.j2` 为后缀, 也可以不写后缀。
  • jinja2 中存在 三种定界符
注释:  {# 注释内容 #}
变量引用: {{ var }}
逻辑表达: {% %}

JinJa2 逻辑控制

{% if %}
...
{% elif %}
...
{% else %}
...
{% endif %}
{# 如果定义了 idc 变量, 则输出 #}
{% if idc is defined %}
{{ idc }}
{% elif %}
没有定义
{% endif %}

循环控制

{% for %}
...
...
{% endfor %}
{# 列举出 dbservers 这个 group 中的所有主机 #}
{% for host in groups['dbservers'] %}
{{ host }}
{% endfor %}


三、使用模板

一个基于Facts的Jinja2

{# use variable example #}
wlecome host {{ ansible_hostname }}, os is {{ ansible_os_family }}
today is {{ ansible_date_time.date }}
cpucore numbers {{ ansible_processor_vcpus }}

{# use condition example #}
{% if ansible_processor_vcpus > 1 %}
OS CPU more than one core
{% endif %}

{% for m in ansible_mounts if m['mount'] != "/" %}
mount {{ m['mount'] }}, total size is {{m['size_total']}}, free size is {{m['size_available']}}
{% endfor %}

在Ansible 中使用模板

---
- name: a template example
hosts: all
remote_user: root
tasks:
- name: update jinja2 config
template: src=config.j2 dest=/tmp/config.conf
...


四、演示

[root@localhost home]# vim nginx.conf.j2

user nginx;
{# start process equal cpu cores #}
worker_processes {{ ansible_processor_vcpus }};

error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;

events {
worker_connections 1024;
}

http {
include /etc/nginx/mime.types;
default_type application/octet-stream;

log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';

sendfile on;
tcp_nopush on;

keepalive_timeout 0;

gzip on;
gzip_min_length 1k;
gzip_buffers 8 64k;
gzip_http_version 1.0;
gzip_comp_level 5;
gzip_types text/plain application/x-javascript text/css application/json application/xml application/x-shockwave-flash application/javascript image/svg+xml image/x-icon;
gzip_vary on;
{# add_header {{ ansible_hostname }}; #}
add_header x-hostname {{ ansible_hostname }};

include /etc/nginx/conf.d/*.conf;
}

优化PlayBook, 支持模板

- name: template playbook example
hosts: webservers
vars:
createuser:
- tomcat
- www
- mysql
tasks:
- name: create user
user: name={{ item }} state=present
with_items: "{{ createuser }}"

- name: yum nginx webserver
yum: name=nginx state=present

name: yum nginx webserver
yum: name=nginx state=present
src: nginx.conf.j2
dest: /etc/nginx/nginx.conf
tags: updateconfig
notify: reload nginx server

- name: add virtualhost config
copy:
src: www.qfedu.com.conf
dest: /etc/nginx/conf.d/
tags: updateconfig
notify: reload nginx server

- name: check nginx syntax
shell: /usr/sbin/nginx -t
register: nginxsyntax
tags: updateconfig

- name: check nginx running
stat: path=/var/run/nginx.pid
register: nginxrunning
tags: updateconfig

- name: print nginx syntax
debug: var=nginxsyntax

- name: start nginx server
service: name=nginx state=started
when:
- nginxsyntax.rc == 0
- nginxrunning.stat.exists == false
handlers:
- name: reload nginx server
service: name=nginx state=started
when:
- nginxsyntax.rc == 0
- nginxrunning.stat.exists == true


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