【SaltStack官方版】—— states教程, part 3 - 定义，包括，延伸

STATES TUTORIAL, PART 3 - TEMPLATING, INCLUDES, EXTENDS

本教程建立在第1部分和第2部分涵盖的主题上。建议您从此开始。这章教程我们将讨论更多  sls 文件的扩展模板和配置技巧。

templating sls modules

SLS modules may require programming logic or inline execution. This is accomplished with module templating. The default module templating system used is Jinja2 and may be configured by changing the renderer value in the master config.

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。

All states are passed through a templating system when they are initially read. To make use of the templating system, simply add some templating markup. An example of an sls module with templating markup may look like this:

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 %}

This templated sls file once generated will look like this:

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

Here's a more complex example:

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 %}

using grains in sls modules

Often times a state will need to behave differently on different systems. Salt grains objects are made available in the template context. The grains can be used from within sls modules:

很多时候，一个state需要在不同的系统上表现不同。Salt grains 对象能在模版上下文中可用。

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.

您可以使用salt ['environ.get']（'VARNAME'）在Salt状态下使用环境变量。

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.fail_without_changes

{% endif %}

calling salt modules from templates

All of the Salt modules loaded by the minion are available within the templating system. This allows data to be gathered in real time on the target system. It also allows for shell commands to be run easily from within the sls modules.

所有由minion加载的Salt模块都可在模板系统中使用。 这允许在目标系统上实时收集数据。 它还允许从sls模块中轻松运行shell命令。

The Salt module functions are also made available in the template context as salt:

Salt模块函数也可以在模板上下文中作为salt使用：

The following example illustrates calling the group_to_gid function in the file execution module with a single positional argument called some_group_that_exists.

以下示例说明使用称为some_group_that_exists的单个位置参数在文件执行模块中调用group_to_gid函数。

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

One way to think about this might be that the gid key is being assigned a value equivelent to the following python pseudo-code:

思考这个问题的一种方法可能是，把gid key当作与下面的python伪代码等效的值：

import salt.modules.file
file.group_to_gid('some_group_that_exists')

Note that for the above example to work, some_group_that_exists must exist before the state file is processed by the templating engine.

请注意，要使上述示例正常工作，在模板引擎处理状态文件之前，必须存在some_group_that_exists。

Below is an example that uses the network.hw_addr function to retrieve the MAC address for eth0:

以下是使用network.hw_addr函数检索eth0的MAC地址的示例：

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

To examine the possible arguments to each execution module function, one can examine the module reference documentation </ref/modules/all>:

检查每个执行模块函数的可能参数，大家可以检查 module reference documentation </ref/modules/all>:

advanced sls module syntax (更高级的SLS模块语法)

Lastly, we will cover some incredibly useful techniques for more complex State trees.

在最后，我们将介绍更复杂的状态树的一些非常有用的技术。

include declaration(包括声明)

A previous example showed how to spread a Salt tree across several files. Similarly, Requisites and Other Global State Arguments span multiple files by using an Include declaration. For example:

前一个示例展示了如何在多个文件中传播Salt 树。 同样，通过使用Include声明，requisites和其他全局状态参数跨越多个文件。 例如：

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:

您可以使用扩展声明修改以前的声明。 例如，以下内容修改了Apache树，以便在vhosts文件更改时重新启动Apache：

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

Using extend with require or watch

The extend statement works differently for require or watch. It appends to, rather than replacing the requisite component.
扩展语句对于require或watch有不同的作用。它附加在，而不是取代必要的组件。

name declaration(命名声明)

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:

您可以使用名称声明覆盖ID声明。 例如，如果按照以下方式进行重写，前面的示例可以更容易维护：

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:

更强大的是使用Names声明来一次覆盖多个状态的ID声明。 这通常可以消除在模板中循环的需要。 例如，本教程中的第一个示例可以在没有循环的情况下重写：

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

In part 4 we will discuss how to use salt's file_roots to set up a workflow in which states can be "promoted" from dev, to QA, to production.

在第4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，在这个工作流程中，可以将状态从开发，质量保证，到生产“推广”。