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Contents
require 'digest/sha2'
Puppet::Parser::Functions::newfunction(:fqdn_rand, :arity => -2, :type => :rvalue, :doc =>
"Usage: `fqdn_rand(MAX, [SEED])`. MAX is required and must be a positive
integer; SEED is optional and may be any number or string.
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.)
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
# We are consciously not using different hash algs based on fips mode here
# since the randomness is not guaranteed to be predictable for a given node
# It just needs to be unique for a given node
seed = Digest::SHA256.hexdigest([self['::fqdn'],max,args].join(':')).hex
Puppet::Util.deterministic_rand_int(seed,max)
end
Version data entries
11 entries across 11 versions & 2 rubygems