Add openbsd_pkg: package management for OpenBSD.

* Code influenced by the service module but without classes.
* Thanks to @dhozac for input and review.
* Thanks to @johanwiren for getting me to push this out the door.

library/openbsd_pkg

+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# (c) 2013, Patrik Lundin <patrik.lundin.swe@gmail.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 re
+
+DOCUMENTATION = '''
+---
+module: openbsd_pkg
+author: Patrik Lundin
+version_added: 1.1
+short_description: Manage packages on OpenBSD.
+description:
+    - Manage packages on OpenBSD using the pkg tools.
+options:
+    name:
+        required: true
+        description:
+        - Name of the package.
+    state:
+        required: true
+        choices: [ present, latest, absent ]
+        description:
+          C(present) will make sure the package is installed.
+          C(latest) will make sure the latest version of the package is installed.
+          C(absent) will make sure the specified package is not installed.
+examples:
+    - description: Make sure nmap is installed
+      code: "openbsd_pkg: name=nmap state=present"
+    - description: Make sure nmap is the latest version
+      code: "openbsd_pkg: name=nmap state=latest"
+    - description: Make sure nmap is not installed
+      code: "openbsd_pkg: name=nmap state=absent"
+'''
+
+# select whether we dump additional debug info through syslog
+syslogging = False
+
+# Function used for executing commands. 
+def execute_command(cmd, syslogging):
+    if syslogging:
+        syslog.openlog('ansible-%s' % os.path.basename(__file__))
+        syslog.syslog(syslog.LOG_NOTICE, 'Command %s' % '|'.join(cmd))
+
+    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    (out, err) = p.communicate()
+    rc = p.returncode
+    return (rc, out, err)
+
+# Function used for getting the name of a currently installed package.
+def get_current_name(name, specific_version):
+    info_cmd = 'pkg_info'
+    (rc, stdout, stderr) = execute_command("%s" % (info_cmd), syslogging)
+    if rc != 0:
+        return (rc, stdout, stderr)
+
+    if specific_version:
+        syntax = "%s"
+    else:
+        syntax = "%s-"
+
+    for line in stdout.splitlines():
+        if syntax % name in line:
+           current_name = line.split()[0]
+
+    return current_name
+
+# Function used to find out if a package is currently installed.
+def get_package_state(name, specific_version):
+    info_cmd = 'pkg_info -e'
+
+    if specific_version:
+        syntax = "%s %s"
+    else:
+        syntax = "%s %s-*"
+
+    rc, stdout, stderr = execute_command(syntax % (info_cmd, name), syslogging)
+
+    if rc == 0:
+        return True
+    else:
+        return False
+
+# Function used to make sure a package is present.
+def package_present(name, installed_state):
+    install_cmd = 'pkg_add -I'
+    if installed_state is False:
+        rc, stdout, stderr = execute_command("%s %s" % (install_cmd, name), syslogging)
+        # pkg_add returns 0 even if the package does not exist
+        # so depend on stderr instead if something bad happened.
+        if stderr:
+            rc = 1
+            changed=False
+        else:
+            changed=True
+    else:
+        rc = 0
+        stdout = ''
+        stderr = ''
+        changed=False
+
+    return (rc, stdout, stderr, changed)
+
+# Function used to make sure a package is the latest available version.
+def package_latest(name, installed_state, specific_version):
+
+    upgrade_cmd = 'pkg_add -u'
+    pre_upgrade_name = ''
+    post_upgrade_name = ''
+    if installed_state is True:
+
+        # pkg_add -u exits 0 even if no update was needed, so compare the
+        # installed package before and after to know if we changed anything.
+        pre_upgrade_name = get_current_name(name, specific_version)
+
+        (rc, stdout, stderr) = execute_command("%s %s" % (upgrade_cmd, name), syslogging)
+
+        # 'pkg_add -u' returns 0 even when something strange happened, stdout
+        # should be empty if everything went fine.
+        if stdout:
+            rc=1
+
+        post_upgrade_name = get_current_name(name, specific_version)
+
+        if pre_upgrade_name == post_upgrade_name:
+            changed = False
+        else:
+            changed = True
+
+        return (rc, stdout, stderr, changed)
+
+    else:
+        # If package was not installed at all just make it present.
+        return package_present(name, installed_state)
+
+# Function used to make sure a package is not installed.
+def package_absent(name, installed_state):
+    remove_cmd = 'pkg_delete -I'
+    if installed_state is True:
+        rc, stdout, stderr = execute_command("%s %s" % (remove_cmd, name), syslogging)
+
+        if rc == 0:
+            changed=True
+        else:
+            changed=False
+    else:
+        rc = 0
+        stdout = ''
+        stderr = ''
+        changed=False
+
+    return (rc, stdout, stderr, changed)
+
+# ===========================================
+# Main control flow
+
+def main():
+    module = AnsibleModule(
+        argument_spec = dict(
+            name = dict(required=True),
+            state = dict(required=True, choices=['absent', 'installed', 'latest', 'present', 'removed']),
+        )
+    )
+
+    name      = module.params['name']
+    state     = module.params['state']
+
+    rc = 0
+    stdout = ''
+    stderr = ''
+    result = {}
+    result['name'] = name
+    result['state'] = state
+
+    # Decide if the name contains a version number.
+    # This regex is based on packages-specs(7).
+    match = re.search("-[0-9]", name)
+    if match:
+        specific_version = True
+    else:
+        specific_version = False
+
+    # Get package state
+    installed_state = get_package_state(name, specific_version)
+
+    # Perform requested action
+    if state in ['installed', 'present']:
+        (rc, stdout, stderr, changed) = package_present(name, installed_state)
+    elif state in ['absent', 'removed']:
+        (rc, stdout, stderr, changed) = package_absent(name, installed_state)
+    elif state == 'latest':
+        (rc, stdout, stderr, changed) = package_latest(name, installed_state, specific_version)
+
+    if rc != 0:
+        if stderr:
+            module.fail_json(msg=stderr)
+        else:
+            module.fail_json(msg=stdout)
+
+    result['changed'] = changed
+
+    module.exit_json(**result)
+
+# this is magic, see lib/ansible/module_common.py
+#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
+main()