examples.cf (39ee1ca62336deb692ae3b7544faee909bb7e47a8c586afa6740f30b4efe5f18)

2.4 kB, 73 lines, CFEngine policy:

bundle agent probabilistic_usebundle(probability, bundlename)
# @brief activate named bundle probabilistically
# @param probability probability that the named bundle will be activated during
# a given agent execution
# @param bundlename the bundle to activate based on the probability
#
# **Example:**
#
# ```cf3
# bundle agent example
# {
#    methods:
#      "Toss Coin"
#        usebundle => probabilistic_usebundle("50", "heads"),
#        comment => "Call bundle heads ~ 50% of the time";
#
#      "Trick Coin"
#        usebundle => probabilistic_usebundle("75", "heads"),
#        comment => "Call bundle heads ~ 75% of the time";
# }
# ```
{
  classes:
    "fifty_fifty"
      expression => strcmp("$(probability)", "50"),
      comment => "We have to special case 50 because of the way dist classes
                  work you would always get 50 defined";
    "not_fifty_fifty" expression => "!fifty_fifty";
    "have_remainder" expression => isvariable("remainder");

    fifty_fifty.have_remainder::
      "activate_bundle"
        dist => { "$(probability)000", "$(remainder)"};

    not_fifty_fifty.have_remainder::
      "activate_bundle"
        dist => { "$(probability)", "$(remainder)"};

  vars:
    fifty_fifty::
      "remainder"
        string => format("%d", eval("((100 - $(probability)) * 1000) +1", "math", "infix"));

    not_fifty_fifty::
      "remainder"
        string => format("%d", eval("100 - $(probability)", "math", "infix"));

  methods:
    fifty_fifty::
      "Activate bundle probabilistically"
        handle => "probabilistic_usebundle_methods_special_case_fifty_fifty_activate_bundle",
        usebundle => $(bundlename),
        if => "activate_bundle_$(probability)000",
        comment => "Activate $(bundlename) $(probability)%ish of the time";

    not_fifty_fifty::
      "Activate bundle probabilistically"
        handle => "probabilistic_usebundle_methods_activate_bundle",
        usebundle => $(bundlename),
        if => "activate_bundle_$(probability)",
        comment => "Activate $(bundlename) $(probability)% of the time";


  reports:
    DEBUG.fifty_fifty::
      "$(this.bundle) Special case for 50/50";

      "$(this.bundle) activate_bundle_$(probability)000"
        if => "activate_bundle_$(probability)000";

      "$(this.bundle) activate_bundle_$(probability)001"
        if => "activate_bundle_$(probability)001";
}