(#13974) Add predicate functions for interface facts

If one wishes to test if a host has a particular IP address (such as a floating
virtual address) or has an interface on a particular network (such as a
secondary management network), the facts that provide this information are
difficult to use within Puppet.

This patch addresses these needs by implementing functions
‘has_ip_address(value)’ and ‘has_ip_network(value)’. These functions look
through all interfaces for ipaddress_<interface> and network_<interface>
(respectively) having the requested <value>.

These functions are implemented on top of a lower-level predicate
function, ‘has_interface_with(kind, value)’, which iterates through the
interfaces in the ‘interfaces’ fact and checks the facts <kind>_<interface>
looking for <value>.

Additionally, the existence of a particular named interface can be checked for
by calling with only a single argument: has_interface_with(interface).

A Boolean is returned in all cases.

1 files changed, 52 insertions, 0 deletions

diff --git a/lib/puppet/parser/functions/has_interface_with.rb b/lib/puppet/parser/functions/has_interface_with.rb
new file mode 100644
index 0000000..7f150a7
--- /dev/null
+++ b/lib/puppet/parser/functions/has_interface_with.rb
@@ -0,0 +1,52 @@
+#
+# has_interface_with
+#
+
+module Puppet::Parser::Functions
+  newfunction(:has_interface_with, :type => :rvalue, :doc => <<-EOS
+Returns boolean based on kind and value:
+  * macaddress
+  * netmask
+  * ipaddress
+  * network
+
+has_interface_with("macaddress", "x:x:x:x:x:x")
+has_interface_with("ipaddress", "127.0.0.1")    => true
+etc.
+
+If no "kind" is given, then the presence of the interface is checked:
+has_interface_with("lo")                        => true
+    EOS
+  ) do |args|
+
+    raise(Puppet::ParseError, "has_interface_with(): Wrong number of arguments " +
+          "given (#{args.size} for 1 or 2)") if args.size < 1 or args.size > 2
+
+    interfaces = lookupvar('interfaces')
+
+    # If we do not have any interfaces, then there are no requested attributes
+    return false if (interfaces == :undefined)
+
+    interfaces = interfaces.split(',')
+
+    if args.size == 1
+      return interfaces.member?(args[0])
+    end
+
+    kind, value = args
+
+    if lookupvar(kind) == value
+      return true
+    end
+
+    result = false
+    interfaces.each do |iface|
+      if value == lookupvar("#{kind}_#{iface}")
+        result = true
+        break
+      end
+    end
+
+    result
+  end
+end