rename infrastructure-guide to engineering guide

engineering-guide/puppet/components/utils.rst

@@ -0,0 +1,32 @@
+``utils``
+=========
+
+This module contains a number of utility functions used at PSI. It is the
+PSI-specific analogue to Puppetlabs' ``stdlib``.
+
+
+Functions
+---------
+
+
+``check_os``
+~~~~~~~~~~~~
+
+Accepts an arbitrary number of arguments, each of which is a string of the form
+``$osfamily $majorversion`` as reported by ``facter(8)``. If the facts of the
+client system **do not** match any of the arguments, the function aborts the
+Puppet run.
+
+
+``rand_time``
+~~~~~~~~~~~~~
+
+This function takes a parameter specifying a time window and returns a specific
+time within this window based on the MD5 on the hostname. This allows scheduling
+cron jobs etc uniformly across a fleet of system within a given window, while
+keeping the time on each system predictable.
+
+The format for the argument specifying the time window is ``HH:MM--HH:MM``. The
+window must not include midnight.
+
+The format of the return value is ``HH:MM``.