Vagrant external inventory file, to dynamically determine your vagrant vm ip.

plugins/inventory/vagrant.py

+#!/usr/bin/env python
+"""
+Vagrant external inventory script. Automatically finds the IP of the booted vagrant system, and
+returns it under the host group 'vagrant'
+
+Example Vagrant configuration using this script:
+
+    config.vm.provision :ansible do |ansible|
+      ansible.playbook = "./provision/your_playbook.yml"
+      ansible.inventory_file = "./provision/inventory/vagrant.py"
+      ansible.verbose = true
+    end
+"""
+
+# Copyright (C) 2013  Mark Mandel <mark@compoundtheory.com>
+#
+# This program 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.
+#
+# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import subprocess
+import re
+
+output = subprocess.check_output(["vagrant", "ssh-config"])
+ip = re.search("HostName ([0-9\.]+)", output).group(1)
+
+print '{ "vagrant" : ["'+ ip +'"] }'
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