Functions in Puppet context

Question

What are functions in puppet?

Answer 1

Functions are plug-ins, written in Ruby, that you can call during catalog compilation. A call to any function is an expression that resolves to a value. Most functions accept one or more values as arguments, and return a resulting value.

Puppet supports functions.It supports two types of functions known with the name of statement and rvalue functions.

• Statements stand on their own and they do not have any return type. They are used for performing standalone tasks like importing other Puppet modules in the new manifest file.
• Rvalue returns values and can only be used when the statement requires a value, such as an assignment or a case statement.

You can write your own functions in the Puppet language to transform data and construct values. A function can optionally take one or more parameters as arguments. A function returns a calculated value from its final expression.

Function Syntax in Puppet: 

function <MODULE NAME>::<NAME>(<PARAMETER LIST>) >> <RETURN TYPE> {  ... body of function ...  final expression, which will be the returned value of the function}

Function Example in Puppet: ​

function apache::bool2http(Variant[String, Boolean] $arg) >> String {  case $arg {    false, undef, /(?i:false)/ : { 'Off' }    true, /(?i:true)/          : { 'On' }    default               : { "$arg" }  }}