A bundle is a collection of promises. They allow to group related promises together into named building blocks that can be thought of as "subroutines" in the CFEngine promise language. A bundle that groups a number of promises related to configuring a web server or a file system would be named "webserver" or "filesystem", respectively.

Most promise types are specific to a particular kind of interpretation that requires a typed interpreter - the bundle type. Bundles belong to the agent that is used to keep the promises in the bundle. So cf-agent has bundles declared as:

    bundle agent my_name

while cf-serverd has bundles declared as:

    bundle server my_name

and cf-monitord has bundles declared as

    bundle monitor my_name

A number of promises can be made in any kind of bundle since they are of a generic input/output nature. These are vars, classes, defaults, meta and reports promises.

Bundles of type common may only contain the promise types that are common to all bodies. Their main function is to define cross-component global definitions.

     bundle common globals

       "global_var" string = "value";


       "global_class" expression = "value";

Common bundles are observed by every agent, whereas the agent specific bundle types are ignored by components other than the intended recipient.

Bundles can be parameterized, allowing for code re-use. If you need to do the same thing over and over again with slight variations, using a promise bundle is an easy way to avoid unnecessary duplication in your promises.

    bundle agent hello_world
          "myfiles"     => "/tmp/world.txt";
          "desired_content" string => "hello";

          "Hello World"
            usebundle => ensure_file_has_content("$(myfiles)", "$(desired_content)");


    bundle agent ensure_file_has_content(file, content)

            handle => "$(this.bundle)_file_content",
            create => "true",
            edit_defaults => empty,
            edit_line => append_if_no_line("$(content)"),
            comment => "Ensure that the given parameter for file '$(file)' has only
                        the contents of the given parameter for content '$(content)'";



Variables and classes defined inside bundles are not directly visible outside those bundles. All variables in CFEngine are globally accessible. However, if you refer to a variable by ‘$(unqualified)’, then it is assumed to belong to the current bundle. To access any other (scalar) variable, you must qualify the name, using the name of the bundle in which it is defined:


Bundles of type common may contain common promises. Classes defined in common bundles have global scope.