Python Jinja2的简单使用

参考链接： https://jinja.palletsprojects.com/en/2.11.x/
下面测试使用jinja2版本： version = "2.11.2" , python版本： version = "3.7.4"

Template使用

from jinja2 import Template
template = Template('Hello {{ name }}')
print(template.render(name='dsg'))
# > output: Hello dsg

template = Template('service: {{ service.name }}, version: {{ service.version }}')
service = {'name': 'mysql', 'version': 5.7}
print(template.render(service=service))
# > output: service: mysql, version: 3.7

template = Template('service: {{ service.name }}, version: {{ service.version }}')
service = {'service': {'name': 'mysql', 'version': 5.7}}
print(template.render(service))

template = Template('service list: {% for s in services %} {{s}};{% endfor %}')
services = {'services': ['mysql', 'nginx']}
print(template.render(services))
# > output: service list:  mysql; nginx;

去除空格

template = Template('service list: {% for s in services -%} {{s}};{%- endfor %}')
services = {'services': ['mysql', 'nginx']}
print(template.render(services))
# > output: service list: mysql;nginx;

直接读j2文件, j2文件示例：

# filename service.j2
name: {{ name }}
version: {{ version }}

with open('app/tmp/service.j2', 'r') as f:
    buffer = f.read()
    service = {'name': 'mysql', 'version': 5.7}
    template = Template(buffer)
    print(template.render(service))
# output:
# > name: mysql
# > version: 5.7

使用模板文件实现部署替换配置文件

# .
# |-- app
# |   |-- __init__.py   # 必须，
# |   |-- tmp
# |       |-- service.js   # 配置文件模板
# |       |-- nginx.js           # 配置文件模板
from jinja2 import Environment, PackageLoader

env = Environment(loader=PackageLoader('app', 'tmp'))
template = env.get_template('service.j2')
content = template.render(name='mysql', version='5.8')

with open('./config', 'w') as f:
    f.write(content)
print(content)
# output:
# > name: mysql
# > version: 5.7

import yaml
with open('app/config.yml') as f:
    y = yaml.safe_load(f)
    print(y)
    template = Template('basedir = {% for node in nodes %} {% if "nginx" in nodes[node].modules %} {{ nodes[node].basedir }} {% endif %}{% endfor %}')
    print(template.render(y))
# output:
# {'nodes': {'node1': {'host': '10.0.0.2', 'basedir': '/data1', 'modules': ['mysql', 'nginx']}, 'node2': {'host': '10.0.0.3', 'basedir': '/data2', 'modules': ['nginx']}}, 'services': {'mysql': {'config': {'port': 3306, 'passwd': 123456}}, 'nginx': {'config': {'port': 8088}}}}
# basedir =   /data1   /data2


env = Environment(loader=PackageLoader('app', 'tmp'))
template = env.get_template('nginx.j2')
content = template.render(y)

with open('./config', 'w') as f:
    f.write(content)
print(content)

nginx.j2文件内容：

version: '2'
services:
  nginx:
    image: nginx:11
    container_name: nginx
    ports:
      - {{ services.nginx.config.port }}:80
    volumes:
    - {% for node in nodes -%} {%- if "nginx" in nodes[node].modules %}{{nodes[node].basedir}}{%- endif %} {%- endfor %}/nginx/logs/:/var/lib/nginx/logs/
    - /usr/share/zoneinfo/Asia/Shanghai:/etc/localtime
    restart: always
    networks:
      - default_bridge
networks:
  default_bridge:
    external: true

config.yml文件内容：

nodes:
  node1:
    host: 10.0.0.2
    basedir: /data1
    modules:
      - mysql
      - nginx
  node2:
    host: 10.0.0.3
    basedir: /data2
    modules:
      - nginx

services:
  mysql:
    config:
      port: 3306
      passwd: 123456
  nginx:
    config:
      port: 8088

config文件最后写入的内容：

version: '2'
services:
  nginx:
    image: nginx:11
    container_name: nginx
    ports:
      - 8088:80
    volumes:
    - /data1/data2/nginx/logs/:/var/lib/nginx/logs/
    - /usr/share/zoneinfo/Asia/Shanghai:/etc/localtime
    restart: always
    networks:
      - default_bridge
networks:
  default_bridge:
    external: true

上面并没有得到我们想要的结果，如果nginx只在一台机器部署的话，结果会是我们想要的，但是多机部署就不行了。
这里我建议尽量少在模板文件中写逻辑判断，逻辑判断应该用python去实现，我们再真实环境中去替换nginx配置的basedir时都是by机器的，我们可以用python先解析出如下格式的数据：

{'10.0.0.2':{'nginx':{'basedir':'/data1'}},
 '10.0.0.2':{'mysql':{'basedir':'/data1'}},
 '10.0.0.3':{'nginx':{'basedir':'/data2'}}
}

如果我们要部署给10.0.0.2部署nginx时就能够正确获取basedir了。 具体怎么实现， 看大家了。

yml里面字典和列表

config.yml

nodes:
  node1:
    host: 10.0.0.2
    basedir: /data1
    modules:
      - mysql
      - nginx
  node2:
    host: 10.0.0.3
    basedir: /data2
    modules:
      - nginx

template = Template(' {{ nodes }}')
print(template.render(y))
# 输出：
 {'node1': {'host': '10.0.0.2', 'basedir': '/data1', 'modules': ['mysql', 'nginx']}, 'node2': {'host': '10.0.0.3', 'basedir': '/data2', 'modules': ['nginx']}}

config.xml

nodes:
  - node1:
      host: 10.0.0.2
      basedir: /data1
      modules:
        - mysql
        - nginx
  - node2:
      host: 10.0.0.3
      basedir: /data2
      modules:
        - nginx

template = Template(' {{ nodes }}')
print(template.render(y))
# 输出：
[{'node1': {'host': '10.0.0.2', 'basedir': '/data1', 'modules': ['mysql', 'nginx']}}, {'node2': {'host': '10.0.0.3', 'basedir': '/data2', 'modules': ['nginx']}}]

yml格式不同，取值就会不同。