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# frozen_string_literal: true
require 'digest/md5'
require 'digest/sha2'
Puppet::Parser::Functions.newfunction(:fqdn_rand, :arity => -2, :type => :rvalue, :doc =>
"Usage: `fqdn_rand(MAX, [SEED], [DOWNCASE])`. MAX is required and must be a positive
integer; SEED is optional and may be any number or string; DOWNCASE is optional
and should be a boolean true or false.
Generates a random Integer number greater than or equal to 0 and less than MAX,
combining the `$fqdn` fact and the value of SEED for repeatable randomness.
(That is, each node will get a different random number from this function, but
a given node's result will be the same every time unless its hostname changes.) If
DOWNCASE is true, then the `fqdn` fact will be downcased when computing the value
so that the result is not sensitive to the case of the `fqdn` fact.
This function is usually used for spacing out runs of resource-intensive cron
tasks that run on many nodes, which could cause a thundering herd or degrade
other services if they all fire at once. Adding a SEED can be useful when you
have more than one such task and need several unrelated random numbers per
node. (For example, `fqdn_rand(30)`, `fqdn_rand(30, 'expensive job 1')`, and
`fqdn_rand(30, 'expensive job 2')` will produce totally different numbers.)") do |args|
max = args.shift.to_i
initial_seed = args.shift
downcase = !!args.shift
fqdn = self['facts'].dig('networking', 'fqdn')
fqdn = fqdn.downcase if downcase
# Puppet 5.4's fqdn_rand function produces a different value than earlier versions
# for the same set of inputs.
# This causes problems because the values are often written into service configuration files.
# When they change, services get notified and restart.
# Restoring previous fqdn_rand behavior of calculating its seed value using MD5
# when running on a non-FIPS enabled platform and only using SHA256 on FIPS enabled
# platforms.
if Puppet::Util::Platform.fips_enabled?
seed = Digest::SHA256.hexdigest([fqdn, max, initial_seed].join(':')).hex
else
seed = Digest::MD5.hexdigest([fqdn, max, initial_seed].join(':')).hex
end
Puppet::Util.deterministic_rand_int(seed, max)
end
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