Policy Style Guide

Style is a very personal choice and the contents of this guide should only be considered suggestions. We invite you to contribute to the growth of this guide.

Style Summary

  • one indent = 2 spaces
  • avoid letting line length surpass 80 characters.
  • vertically align opening and closing curly braces unless on same line
  • promise type = 1 indent
  • context class expression = 2 indents
  • promiser = 3 indents
  • promise attributes = (we suggest 3 or 4 indents)

Whitespace and Line Length

Spaces are preferred to tab characters. Lines should not have trailing whitespace. Generally line length should not surpass 80 characters.

Curly brace alignment

Generally if opening and closing braces are not on a single line they should be aligned vertically.

Example:

    bundle agent example
    {
      vars:
          "people" slist => {
                              "Obi-Wan Kenobi",
                              "Luke Skywalker",
                              "Chewbacca",
                              "Yoda",
                              "Darth Vader",
                            };

          "cuddly" slist => { "Chewbacca", "Yoda" };
    }

Promise types

Promise types should have 1 indent and each promise type after the first listed should have a blank line before the next promise type.

This example illustrates the blank line before the "classes" type.

    bundle agent example
    {
      vars:
          "policyhost" string => "MyPolicyServerHostname";

      classes:
          "EL5" or => { "centos_5", "redhat_5" };
          "EL6" or => { "centos_6", "redhat_6" };
    }

Context class expressions

Context class expressions should have 2 indents and each context class expression after the first listed within a given promise type should have a blank line preceding it.

This example illustrates the blank line before the second context class expression (solaris) in the files type promise section:

    bundle agent example
    {
      files:
        any::
          "/var/cfengine/inputs/"
            copy_from    => update_policy( "/var/cfengine/masterfiles","$(policyhost)" ),
            classes      => policy_updated( "policy_updated" ),
            depth_search => recurse("inf");

        solaris::
          "/var/cfengine/inputs"
            copy_from => update_policy( "/var/cfengine/masterfiles", "$(policyhost" ),
            classes   => policy_updated( "policy_updated" );
    }

Policy Comments

In-line policy comments are useful for debugging and explaining why something is done a specific way. We encourage you to document your policy throughly.

Comments about general body and bundle behavior and parameters should be placed after the body or bundle definition, before the opening curly brace and should not be indented. Comments about specific promise behavior should be placed before the promise at the same indention level as the promiser or on the same line after the attribute.

    bundle agent example(param1)
    # This is an example bundle to illustrate comments
    # param1 - string - 
    {
      vars:
          "copy_of_param1" string => "$(param1)";

          "jedi" slist => { 
                            "Obi-Wan Kenobi",
                            "Luke Skywalker",
                            "Yoda",
                            "Darth Vader", # He used to be a Jedi, and since he
                                           # tossed the emperor into the Death
                                           # Star's reactor shaft we are including
                                           # him.
                          };
      classes:
          # Most of the time we don't need differentiation of redhat and centos
          "EL5" or => { "centos_5", "redhat_5" };
          "EL6" or => { "centos_6", "redhat_6" };
    }

Hashrockets (=>)

Hash rockets should be aligned within a promise body scope and for grouped single line promises.

Example:

    bundle agent example
    {
      files:
        any::
          "/var/cfengine/inputs/"
            copy_from    => update_policy( "/var/cfengine/masterfiles","$(policyhost)" ),
            classes      => policy_updated( "policy_updated" ),
            depth_search => recurse("inf");

          "/var/cfengine/modules"
            copy_from => update_policy( "/var/cfengine/modules", "$(policyhost" ),
            classes   => policy_updated( "modules_updated" );

      classes:
          "EL5" or => { "centos_5", "redhat_5" };
          "EL6" or => { "centos_6", "redhat_6" };
    }

Automatic reindentation

You can run contrib/reindent.pl FILE1.cf FILE2.c FILE3.h to reindent files, if you don't want to set up Emacs. It will rewrite them with the new indentation, using Emacs in batch mode.

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