Added a $PIPE_ONCE lookup plugin, that caches the result so it is only evaluated one time.

lib/ansible/runner/lookup_plugins/pipe_once.py

@@ -0,0 +1,45 @@
+# (c) 2012, Daniel Hokka Zakrisson <daniel@hozac.com>
+#
+# This file is part of Ansible
+#
+# Ansible is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+import subprocess
+from ansible import utils, errors
+
+CACHE = {}
+
+class LookupModule(object):
+
+    def __init__(self, basedir=None, **kwargs):
+        self.basedir = basedir
+
+    def run(self, terms, **kwargs):
+
+
+        if isinstance(terms, basestring):
+            terms = [ terms ]
+        ret = []
+        for term in terms:
+            if term in CACHE:
+                ret.append(CACHE.get(term)
+            p = subprocess.Popen(term, cwd=self.basedir, shell=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+            (stdout, stderr) = p.communicate()
+            if p.returncode == 0:
+                result = stdout.strip()
+                CACHE[term] = result
+                ret.append(result)
+            else:
+                raise errors.AnsibleError("lookup_plugin.pipe(%s) returned %d" % (term, p.returncode))
+        return ret