[lnst] Common: Adding VirtUtils module

[Jiří Pírko]

commit fd3977338b84246c1d3001262f2e5d125d1cc57e
Author: Radek Pazdera <rpazdera(a)redhat.com&gt;
Date:   Mon Aug 13 12:01:51 2012 +0200

    Common: Adding VirtUtils module
    
    This commit adds VirtUtils module to Common.
    
    VirtUtils is a set of classes that can be used to manage virtual
    domains and networks.
    
    VirtDomainCtl can control libvirt domains,
    VirtNetCtl can control libvirt networks,
    BridgeCtl can control network bridges.
    
    Signed-off-by: Radek Pazdera <rpazdera(a)redhat.com&gt;

 Common/VirtUtils.py |  242 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 242 insertions(+), 0 deletions(-)
---
diff --git a/Common/VirtUtils.py b/Common/VirtUtils.py
new file mode 100644
index 0000000..28a3d7e
--- /dev/null
+++ b/Common/VirtUtils.py
@@ -0,0 +1,242 @@
+"""
+Utilities for manipulating virtualization host, its guests and
+connections between them
+
+Copyright 2012 Red Hat, Inc.
+Licensed under the GNU General Public License, version 2 as
+published by the Free Software Foundation; see COPYING for details.
+"""
+
+__author__ = """
+rpazdera(a)redhat.com (Radek Pazdera)
+"""
+
+import os
+import re
+import copy
+import time
+import logging
+from tempfile import NamedTemporaryFile
+from xml.dom import minidom
+from ExecCmd import exec_cmd, ExecCmdFail
+from Common.NetUtils import normalize_hwaddr, scan_netdevs
+
+class VirtUtilsError(Exception):
+    pass
+
+def _ip(cmd):
+    try:
+        exec_cmd("ip %s" % cmd)
+    except ExecCmdFail as err:
+        raise VirtUtilsError("ip command error: %s" % err)
+
+def _brctl(cmd):
+    try:
+        exec_cmd("brctl %s" % cmd)
+    except ExecCmdFail as err:
+        raise VirtUtilsError("brctl error: %s" % err)
+
+def _virsh(cmd):
+    try:
+        exec_cmd("virsh %s" % cmd)
+    except ExecCmdFail as err:
+        raise VirtUtilsError("virsh error: %s" % err)
+
+
+class VirtDomainCtl:
+    _name = None
+
+    def __init__(self, domain_name):
+        self._name = domain_name
+
+    def start(self):
+        _virsh("start %s" % self._name)
+
+    def stop(self):
+        _virsh("destroy %s" % self._name)
+
+    def restart(self):
+        _virsh("reboot %s" % self._name)
+
+    def attach_interface(self, hwaddr, net_name, net_type="bridge"):
+        _virsh("attach-interface %s %s %s --mac %s" % \
+                            (self._name, net_type, net_name, hwaddr))
+        self.ifup(hwaddr)
+
+    def detach_interface(self, hwaddr, net_type="bridge"):
+        _virsh("detach-interface %s %s %s" % (self._name, net_type, hwaddr))
+
+    def ifup(self, hwaddr):
+        _virsh("domif-setlink %s %s up" % (self._name, hwaddr))
+
+    def ifdown(self, hwaddr):
+        _virsh("domif-setlink %s %s down" % (self._name, hwaddr))
+
+class NetCtl(object):
+    _name = None
+
+    def __init__(self, name):
+        self._name = name
+
+    def get_name(self):
+        return self._name
+
+    def init(self):
+        pass
+
+    def cleanup(self):
+        pass
+
+class VirtNetCtl(NetCtl):
+    _addr = None
+    _mask = None
+
+    _dhcp_from = None
+    _dhcp_to = None
+    _static_mappings = []
+    _lease_file = None
+
+    def setup_dhcp_server(self, addr, mask, range_start, range_end,
+                                    static_map=None):
+        self._addr = addr
+        self._mask = mask
+        self._dhcp_from = range_start
+        self._dhcp_to = range_end
+        self._lease_file = "/var/lib/libvirt/dnsmasq/%s.leases" % self._name
+        if static_map:
+            self._static_mappings = static_map
+
+    def get_dhcp_mapping(self, hwaddr, timeout=30):
+        wait = timeout
+        while True:
+            addr = self._get_map(hwaddr)
+            if addr or not wait:
+                break
+
+            time.sleep(1)
+            wait -= 1
+
+        return addr
+
+    def _get_map(self, hwaddr):
+
+        try:
+            leases_file = open(self._lease_file, "r")
+        except IOError as err:
+            raise VirtUtilsError("Unable to resolve IP mapping (%s)" % err)
+
+        addr = None
+        normalized_hwaddr = normalize_hwaddr(hwaddr)
+        for entry in leases_file:
+            match = re.match(r"\d+\s+([0-9a-f:]+)\s+([0-9\.]+)", entry)
+            if match:
+                entry_hwaddr = normalize_hwaddr(match.group(1))
+                entry_addr = match.group(2)
+                if entry_hwaddr == normalized_hwaddr:
+                    addr = entry_addr
+                    break
+
+        leases_file.close()
+        return addr
+
+
+    def init(self):
+        tmp_file = NamedTemporaryFile(delete=False)
+        doc = self._get_net_xml_dom()
+
+        doc.writexml(tmp_file)
+        tmp_file.close()
+
+        _virsh("net-create %s" % tmp_file.name)
+        os.unlink(tmp_file.name)
+
+    def cleanup(self):
+        _virsh("net-destroy %s" % self._name)
+        exec_cmd("rm -f %s" % self._lease_file)
+
+    def _get_net_xml_dom(self):
+        doc = minidom.Document()
+
+        net = doc.createElement("network")
+        doc.appendChild(net)
+
+        name = doc.createElement("name")
+        name_text = doc.createTextNode(self._name)
+        name.appendChild(name_text)
+        net.appendChild(name)
+
+        if self._addr:
+            ip = doc.createElement("ip")
+            ip.setAttribute("address", self._addr)
+            ip.setAttribute("netmask", self._mask)
+            net.appendChild(ip)
+
+            dhcp = doc.createElement("dhcp")
+            ip.appendChild(dhcp)
+
+            dhcp_range = doc.createElement("range")
+            dhcp_range.setAttribute("start", self._dhcp_from)
+            dhcp_range.setAttribute("end", self._dhcp_to)
+            dhcp.appendChild(dhcp_range)
+
+            for mapping in self._static_mappings:
+                hwaddr, addr = mapping
+                host = doc.createElement("host")
+                host.setAttribute("mac", hwaddr)
+                host.setAttribute("ip", addr)
+                dhcp.appendChild(host)
+
+        return doc
+
+class BridgeCtl(NetCtl):
+    _remove = False
+
+    def __init__(self, name=None):
+        if not name:
+            name = self._generate_name()
+
+        self._check_name(name)
+        self._name = name
+
+    @staticmethod
+    def _check_name(name):
+        if len(name) > 16:
+            msg = "Bridge name '%s' longer than 16 characters" % name
+            raise VirtUtilsError(msg)
+
+    @staticmethod
+    def _generate_name():
+        devs = scan_netdevs()
+
+        index = 0
+        while True:
+            name = "lnstbr%d" % index
+            index += 1
+            unique = True
+            for dev in devs:
+                if name == dev["name"]:
+                    unique = False
+                    break
+
+            if unique:
+                return name
+
+    def _exists(self):
+        devs = scan_netdevs()
+        for dev in devs:
+            if self._name == dev["name"]:
+                return True
+
+        return False
+
+    def init(self):
+        if not self._exists():
+            _brctl("addbr %s" % self._name)
+            self._remove = True
+
+        _ip("link set %s up" % self._name)
+
+    def cleanup(self):
+        if self._remove:
+            _ip("link set %s down" % self._name)
+            _brctl("delbr %s" % self._name)