Puppet 简明教程

Puppet - Classes

Puppet 类定义为资源的集合，这些资源被分组在一起，以便使目标节点或机器处于所需状态。这些类在位于 Puppet 模块中的 Puppet 清单文件中定义。使用类的主要目的是减少任何清单文件或任何其他 Puppet 代码中的相同代码重复。

Puppet classes are defined as a collection of resources, which are grouped together in order to get a target node or machine in a desired state. These classes are defined inside Puppet manifest files which is located inside Puppet modules. The main purpose of using a class is to reduce the same code repetition inside any manifest file or any other Puppet code.

以下是 Puppet 类的示例。

Following is an example of Puppet class.

[root@puppetmaster manifests]# cat site.pp
class f3backup (
   $backup_home   = '/backup',
   $backup_server = 'default',
   $myname        = $::fqdn,
   $ensure        = 'directory',
) {
   include '::f3backup::common'
   if ( $myname == '' or $myname == undef ) {
      fail('myname must not be empty')
   }
   @@file { "${backup_home}/f3backup/${myname}":
      # To support 'absent', though force will be needed
      ensure => $ensure,
      owner  => 'backup',
      group  => 'backup',
      mode   => '0644',
      tag    => "f3backup-${backup_server}",
   }
}

在上面的示例中，我们有两个用户需要存在的客户端。如可以注意到的，我们重复了相同资源两次。一种不执行相同任务的方法是组合两个节点。

In the above example, we have two clients where the user needs to exist. As can be noticed we have repeated the same resource twice. One way of not doing the same task in combining the two nodes.

[root@puppetmaster manifests]# cat site.pp
node 'Brcleprod001','Brcleprod002' {
   user { 'vipin':
      ensure => present,
      uid    => '101',
      shell  => '/bin/bash',
      home   => '/home/homer',
   }
}

以这种方式合并节点来执行配置不是一个好习惯。这可以通过创建一个类，并将创建的类包含在节点中来轻松实现，如下所示。

Merging nodes in this fashion to perform the configuration is not a good practice. This can be simply achieved by creating a class and including the created class in nodes which is shown as follows.

class vipin_g01063908 {
   user { 'g01063908':
      ensure => present,
      uid    => '101',
      shell  => '/bin/bash',
      home   => '/home/g01063908',
   }
}
node 'Brcleprod001' {
   class {vipin_g01063908:}
}
node 'Brcleprod002' {
   class {vipin_g01063908:}
}

需要注意的是类结构的外观，以及我们如何使用 class 关键字添加新资源。Puppet 中的每个语法都有其自己的特征。因此，选择哪种语法取决于条件。

The point to be noticed is how the class structure looks like and how we added a new resource using the class keyword. Each syntax in Puppet has its own feature. Hence, the syntax one picks depend on the conditions.

Parameterized Class

如上面的示例中所示，我们已经了解了如何创建类并将其包含在节点中。现在，有时我们需要在每个节点上具有不同的配置，例如当需要使用同一类在每个节点上具有不同用户时。此功能在 Puppet 中使用参数化类提供。新类的配置将如下面的示例所示。

As in the above example, we have seen how to create a class and include it in a node. Now there are situations when we need to have different configurations on each node such as when one needs to have different users on each node using the same class. This feature is provided in Puppet using parameterized class. The configuration for a new class will look as shown in the following example.

[root@puppetmaster ~]# cat /etc/puppet/manifests/site.pp
class user_account ($username){
   user { $username:
      ensure => present,
      uid    => '101',
      shell  => '/bin/bash',
      home   => "/home/$username",
   }
}
node 'Brcleprod002' {
   class { user_account:
      username => "G01063908",
   }
}
node 'Brcleprod002' {
   class {user_account:
      username => "G01063909",
   }
}

当我们对节点应用上述 site.pp 清单时，每个节点的输出将如下所示。

When we apply the above site.pp manifest on nodes, then the output for each node will look like the following.

Brcleprod001

[root@puppetagent1 ~]# puppet agent --test
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Caching catalog for puppetagent1.testing.dyndns.org
Info: Applying configuration version '1419452655'

Notice: /Stage[main]/User_account/User[homer]/ensure: created
Notice: Finished catalog run in 0.15 seconds
[root@brcleprod001 ~]# cat /etc/passwd | grep "vipin"
G01063908:x:101:501::/home/G01063909:/bin/bash

Brcleprod002

[root@Brcleprod002 ~]# puppet agent --test
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Caching catalog for puppetagent2.testing.dyndns.org
Info: Applying configuration version '1419452725'

Notice: /Stage[main]/User_account/User[bart]/ensure: created
Notice: Finished catalog run in 0.19 seconds
[root@puppetagent2 ~]# cat /etc/passwd | grep "varsha"
G01063909:x:101:501::/home/G01063909:/bin/bash

还可以设置类参数的默认值，如以下代码所示。

One can also set the default value of a class parameter as shown in the following code.

[root@puppetmaster ~]# cat /etc/puppet/manifests/site.pp
class user_account ($username = ‘g01063908'){
   user { $username:
      ensure => present,
      uid    => '101',
      shell  => '/bin/bash',
      home   => "/home/$username",
   }
}
node 'Brcleprod001' {
   class {user_account:}
}
node 'Brcleprod002' {
   class {user_account:
      username => "g01063909",
   }
}