Type aliases allow you to create reusable and descriptive data and resource types.
Type aliases are written as:
type <MODULE NAME>::<ALIAS NAME> = <TYPE DEFINITION>
The <MODULE NAME>
must be named after the module that contains the type alias, and both the <MODULE NAME>
and <ALIAS NAME>
begin with a capital letter and must not be a reserved word.
For example, you can create a type alias named MyType
that is equivalent to the Integer
data type:
type MyModule::MyType = Integer
You can then declare a parameter using the alias as though it were a unique data type:
MyModule::MyType $example = 10
By using type aliases, you can:
IPv6Addr
, instead of creating or using a complex pattern-based type.Type aliases are transparent, which means they are fully equivalent to the types of which they are aliases. For instance, this example’s notice
returns true
because MyType
is an alias of the Integer
type:
type MyModule::MyType = Integer
notice MyModule::MyType == Integer
Note: The internal types
TypeReference
andTypeAlias
are never values in Puppet code.
If you define type aliases inside of manifests that contain other Puppet code, you make it more difficult to find where and how they are defined. It’s easier to maintain and diagnose problems with type aliases by placing them into files within their own directory of your Puppet module.
Store type aliases as .pp
files in your module’s types
directory, which is a top-level directory and sibling of the manifests
and lib
directories. Define only one alias per file, and name the file after the type alias name converted to lowercase. For example, MyType
is expected to be loaded from a file named mytype.pp
.
You can create recursive types:
type MyModule::Tree = Array[Variant[Data, Tree]]
This Tree
type alias is defined as a being built out of Arrays that contain Data, or a Tree:
[1,2 [3], [4, [5, 6], [[[[1,2,3]]]]]]
A recursive alias can refer to the alias being declared, or to other types.
This powerful mechanism allows you to define complex, descriptive type definitions instead of using the Any
type.
You can also create aliases to resource types.
type MyModule::MyFile = File
When defining an alias to a resource type, use its short form (such as File
) instead of its long form (such as Resource[File]
).