States tutorial, part 3 - Templating, Includes, Extends¶

注解

提示：本教程建立在:doc:part 1 <states_pt1> 和:doc:`part 2 <states_pt2>`之上，建议从它们开始阅读

这章教程我们将讨论更多 ``sls``文件的扩展模板和配置技巧。

模板SLS的模块¶

SLS模板块可能需要编程的逻辑或则嵌套的执行。这是通过模块的模板，默认的模块模板系统使用的是`Jinja2`，我们可以通过更改主配置的:conf_master:`renderer`值来改变这个。

当初始化时所有的状态类型都是通过模板系统获得。使用模板系统只需要简单的添加一些模板标记。SLS模板与模板标记的一个例子，看起来像下面这样。

{% for usr in ['moe','larry','curly'] %}
{{ usr }}:
  user.present
{% endfor %}

这个SLS模板文件一次性构造了如下的内容：

moe:
  user.present
larry:
  user.present
curly:
  user.present

这里有个更复杂点的例子：

# Comments in yaml start with a hash symbol.
# Since jinja rendering occurs before yaml parsing, if you want to include jinja
# in the comments you may need to escape them using 'jinja' comments to prevent
# jinja from trying to render something which is not well-defined jinja.
# e.g.
# {# iterate over the Three Stooges using a {% for %}..{% endfor %} loop
# with the iterator variable {{ usr }} becoming the state ID. #}
{% for usr in 'moe','larry','curly' %}
{{ usr }}:
  group:
    - present
  user:
    - present
    - gid_from_name: True
    - require:
      - group: {{ usr }}
{% endfor %}

使用grains模板¶

很多时候一个state 在不同的系统上行为要不一样， Salt grains 在模板文本中将可以被应用，`grains`可以被使用在模板内。

apache:
  pkg.installed:
    {% if grains['os'] == 'RedHat' %}
    - name: httpd
    {% elif grains['os'] == 'Ubuntu' %}
    - name: apache2
    {% endif %}

Using Environment Variables in SLS modules¶

You can use salt['environ.get']('VARNAME') to use an environment variable in a Salt state.

MYENVVAR="world" salt-call state.template test.sls

 Create a file with contents from an environment variable:
file.managed:
  - name: /tmp/hello
  - contents: {{ salt['environ.get']('MYENVVAR') }}

Error checking:

{% set myenvvar = salt['environ.get']('MYENVVAR') %}
{% if myenvvar %}

Create a file with contents from an environment variable:
  file.managed:
    - name: /tmp/hello
    - contents: {{ salt['environ.get']('MYENVVAR') }}

{% else %}

Fail - no environment passed in:
  test:
    A. fail_without_changes

{% endif %}

在模板中调用模块¶

所有的minion从模板系统中调用可用的模块。他们允许实时在目标机器上搜集数据。同时也允许运行简单shell命令在SLS模块中。

``salt:``一个可用的模块函数在salt模板中,就像下面这样。

moe:
  user.present:
    - gid: {{ salt['file.group_to_gid']('some_group_that_exists') }}

提示：在上面的例子运行中，some_group_that_exists 必须在状态文件模板引擎处理之前必须存在。

在下面的例子中使用``network.hw_addr``函数取回eth0的MAC地址。

salt['network.hw_addr']('eth0')

更高级的SLS模块语法¶

在最后，我们将讨论一些不可思议的好技巧在更复杂的state 树中。

Include declaration¶

A previous example showed how to spread a Salt tree across several files. Similarly, requisites span multiple files by using an Include declaration. For example:

python/python-libs.sls:

python-dateutil:
  pkg.installed

python/django.sls:

include:
  - python.python-libs

django:
  pkg.installed:
    - require:
      - pkg: python-dateutil

Extend declaration¶

You can modify previous declarations by using an Extend declaration. For example the following modifies the Apache tree to also restart Apache when the vhosts file is changed:

apache/apache.sls:

apache:
  pkg.installed

apache/mywebsite.sls:

include:
  - apache.apache

extend:
  apache:
    service:
      - running
      - watch:
        - file: /etc/httpd/extra/httpd-vhosts.conf

/etc/httpd/extra/httpd-vhosts.conf:
  file.managed:
    - source: salt://apache/httpd-vhosts.conf

对比扩展和`required`or watch

扩展申明申明是有别于``require``or watch,它是附加，而不是更改必要的组件。

Name declaration¶

You can override the ID declaration by using a Name declaration. For example, the previous example is a bit more maintainable if rewritten as follows:

apache/mywebsite.sls:

include:
  - apache.apache

extend:
  apache:
    service:
      - running
      - watch:
        - file: mywebsite

mywebsite:
  file.managed:
    - name: /etc/httpd/extra/httpd-vhosts.conf
    - source: salt://apache/httpd-vhosts.conf

Names declaration¶

Even more powerful is using a Names declaration to override the ID declaration for multiple states at once. This often can remove the need for looping in a template. For example, the first example in this tutorial can be rewritten without the loop:

stooges:
  user.present:
    - names:
      - moe
      - larry
      - curly

下一章¶

在 第四部分中 我们将讨论如何使用**Salt**的 file_roots 来建立一个工作流程状态提升从开发,测试,生产。