[libvirt] [question]Is there a good way to get the mac of guest interface after I attached it to a guest
Now I working on a new KVM management tool base on html5 and libvirt we will support a REST API for detach and attach guest interface. we want to use mac as the identifier of the network interface. That meas we should get the mac after the user create a interface. also other people may be doing the exact same thing at the exact same time to create a interface. Here are the demo codes: dom = self._get_vm(vm) xml = """ <interface type='network'> <source network='default'/> </interface> """ dom.attachDeviceFlags(xml, libvirt.VIR_DOMAIN_AFFECT_CURRENT) # now I want to get the mac, how to get it? I have check libvirt use this code to generate a mac address. does libvirt can gurantee that the MAC address generated is unique? void virMacAddrGenerate(const unsigned char prefix[VIR_MAC_PREFIX_BUFLEN], virMacAddrPtr addr) { addr->addr[0] = prefix[0]; addr->addr[1] = prefix[1]; addr->addr[2] = prefix[2]; addr->addr[3] = virRandomBits(8); addr->addr[4] = virRandomBits(8); addr->addr[5] = virRandomBits(8); } libvirt also use the KVM prefix as default as it's in the privately administered range: 52:54:00:XX:XX:XX -- Thanks and best regards! Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
----- Original Message -----
Now I working on a new KVM management tool base on html5 and libvirt
we will support a REST API for detach and attach guest interface.
we want to use mac as the identifier of the network interface.
That meas we should get the mac after the user create a interface. also other people may be doing the exact same thing at the exact same time to create a interface.
Here are the demo codes:
dom = self._get_vm(vm) xml = """ <interface type='network'> <source network='default'/> </interface> """
This interface xml is partial, and it is not recommended according to 'man virsh': " Note: using of partial device definition XML files may lead to unexpected results as some fields may be autogenerated and thus match devices other than expected. " And there is a way to find out the mac address specified by libvirt, we can check /var/lib/libvirt/dnsmasq/default.leases, newer one is on top # cat /var/lib/libvirt/dnsmasq/default.leases 1390549166 52:54:00:ea:9f:58 192.168.122.106 * * 1390547957 52:54:00:9d:43:38 192.168.122.134 * * 1390547828 52:54:00:0b:2f:ec 192.168.122.76 localhost * But seems there is some latency, :(
dom.attachDeviceFlags(xml, libvirt.VIR_DOMAIN_AFFECT_CURRENT) # now I want to get the mac, how to get it?
I have check libvirt use this code to generate a mac address. does libvirt can gurantee that the MAC address generated is unique?
yes, I also have this question.
void virMacAddrGenerate(const unsigned char prefix[VIR_MAC_PREFIX_BUFLEN], virMacAddrPtr addr) { addr->addr[0] = prefix[0]; addr->addr[1] = prefix[1]; addr->addr[2] = prefix[2]; addr->addr[3] = virRandomBits(8); addr->addr[4] = virRandomBits(8); addr->addr[5] = virRandomBits(8); } libvirt also use the KVM prefix as default as it's in the privately administered range: 52:54:00:XX:XX:XX
-- Thanks and best regards!
Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
On 01/24/2014 02:40 PM, Jincheng Miao wrote:
----- Original Message -----
Now I working on a new KVM management tool base on html5 and libvirt
we will support a REST API for detach and attach guest interface.
we want to use mac as the identifier of the network interface.
That meas we should get the mac after the user create a interface. also other people may be doing the exact same thing at the exact same time to create a interface.
Here are the demo codes:
dom = self._get_vm(vm) xml = """ <interface type='network'> <source network='default'/> </interface> """ This interface xml is partial, and it is not recommended according to 'man virsh': " Note: using of partial device definition XML files may lead to unexpected results as some fields may be autogenerated and thus match devices other than expected. "
And there is a way to find out the mac address specified by libvirt, we can check /var/lib/libvirt/dnsmasq/default.leases, newer one is on top # cat /var/lib/libvirt/dnsmasq/default.leases 1390549166 52:54:00:ea:9f:58 192.168.122.106 * * 1390547957 52:54:00:9d:43:38 192.168.122.134 * * 1390547828 52:54:00:0b:2f:ec 192.168.122.76 localhost *
But seems there is some latency, :( yes, but only the vm is running, we can get the mac and IP.
dom.attachDeviceFlags(xml, libvirt.VIR_DOMAIN_AFFECT_CURRENT) # now I want to get the mac, how to get it?
I have check libvirt use this code to generate a mac address. does libvirt can gurantee that the MAC address generated is unique? yes, I also have this question.
void virMacAddrGenerate(const unsigned char prefix[VIR_MAC_PREFIX_BUFLEN], virMacAddrPtr addr) { addr->addr[0] = prefix[0]; addr->addr[1] = prefix[1]; addr->addr[2] = prefix[2]; addr->addr[3] = virRandomBits(8); addr->addr[4] = virRandomBits(8); addr->addr[5] = virRandomBits(8); } libvirt also use the KVM prefix as default as it's in the privately administered range: 52:54:00:XX:XX:XX
-- Thanks and best regards!
Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
-- Thanks and best regards! Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
On Fri, Jan 24, 2014 at 10:37:20AM +0800, Sheldon wrote:
Now I working on a new KVM management tool base on html5 and libvirt
we will support a REST API for detach and attach guest interface.
we want to use mac as the identifier of the network interface.
That meas we should get the mac after the user create a interface. also other people may be doing the exact same thing at the exact same time to create a interface.
Here are the demo codes:
dom = self._get_vm(vm) xml = """ <interface type='network'> <source network='default'/> </interface> """ dom.attachDeviceFlags(xml, libvirt.VIR_DOMAIN_AFFECT_CURRENT) # now I want to get the mac, how to get it?
You have to parse the XML back and find it.
I have check libvirt use this code to generate a mac address. does libvirt can gurantee that the MAC address generated is unique?
No, as mentioned in the second subthread, the XML you provided is incomplete and can cause address clashing. So te best answer to your question in $SUBJ would be "generate it yourself and add it to the XML before attaching". Martin
void virMacAddrGenerate(const unsigned char prefix[VIR_MAC_PREFIX_BUFLEN], virMacAddrPtr addr) { addr->addr[0] = prefix[0]; addr->addr[1] = prefix[1]; addr->addr[2] = prefix[2]; addr->addr[3] = virRandomBits(8); addr->addr[4] = virRandomBits(8); addr->addr[5] = virRandomBits(8); } libvirt also use the KVM prefix as default as it's in the privately administered range: 52:54:00:XX:XX:XX
-- Thanks and best regards!
Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
On 01/24/2014 03:55 PM, Martin Kletzander wrote:
On Fri, Jan 24, 2014 at 10:37:20AM +0800, Sheldon wrote:
Now I working on a new KVM management tool base on html5 and libvirt
we will support a REST API for detach and attach guest interface.
we want to use mac as the identifier of the network interface.
That meas we should get the mac after the user create a interface. also other people may be doing the exact same thing at the exact same time to create a interface.
Here are the demo codes:
dom = self._get_vm(vm) xml = """ <interface type='network'> <source network='default'/> </interface> """ dom.attachDeviceFlags(xml, libvirt.VIR_DOMAIN_AFFECT_CURRENT) # now I want to get the mac, how to get it?
You have to parse the XML back and find it.
I have check libvirt use this code to generate a mac address. does libvirt can gurantee that the MAC address generated is unique?
No, as mentioned in the second subthread, the XML you provided is incomplete and can cause address clashing.
So te best answer to your question in $SUBJ would be "generate it yourself and add it to the XML before attaching".
now I define a mac address generator in our management tool. it will generate a mac and assign it xml before create the interface. + def randomMAC(): + mac = [0x52, 0x54, 0x00, + random.randint(0x00, 0x7f), + random.randint(0x00, 0xff), + random.randint(0x00, 0xff)] + mac = randomMAC() + xml = """ + <interface type='network'> + <source network='default'/> + <mac address='%s' > + </interface> + """ % mac should I gurantee that the MAC address generated is unique by myself? check every interface mac of every guest, and make sure no address clashing? I wonder can libvirt support a API to generate mac address?
Martin
void virMacAddrGenerate(const unsigned char prefix[VIR_MAC_PREFIX_BUFLEN], virMacAddrPtr addr) { addr->addr[0] = prefix[0]; addr->addr[1] = prefix[1]; addr->addr[2] = prefix[2]; addr->addr[3] = virRandomBits(8); addr->addr[4] = virRandomBits(8); addr->addr[5] = virRandomBits(8); } libvirt also use the KVM prefix as default as it's in the privately administered range: 52:54:00:XX:XX:XX
-- Thanks and best regards!
Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
-- Thanks and best regards! Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
On Fri, Jan 24, 2014 at 04:34:12PM +0800, Sheldon wrote:
On 01/24/2014 03:55 PM, Martin Kletzander wrote:
On Fri, Jan 24, 2014 at 10:37:20AM +0800, Sheldon wrote:
Now I working on a new KVM management tool base on html5 and libvirt
we will support a REST API for detach and attach guest interface.
we want to use mac as the identifier of the network interface.
That meas we should get the mac after the user create a interface. also other people may be doing the exact same thing at the exact same time to create a interface.
Here are the demo codes:
dom = self._get_vm(vm) xml = """ <interface type='network'> <source network='default'/> </interface> """ dom.attachDeviceFlags(xml, libvirt.VIR_DOMAIN_AFFECT_CURRENT) # now I want to get the mac, how to get it?
You have to parse the XML back and find it.
I have check libvirt use this code to generate a mac address. does libvirt can gurantee that the MAC address generated is unique?
No, as mentioned in the second subthread, the XML you provided is incomplete and can cause address clashing.
So te best answer to your question in $SUBJ would be "generate it yourself and add it to the XML before attaching".
now I define a mac address generator in our management tool. it will generate a mac and assign it xml before create the interface.
+ def randomMAC(): + mac = [0x52, 0x54, 0x00, + random.randint(0x00, 0x7f), + random.randint(0x00, 0xff), + random.randint(0x00, 0xff)] + mac = randomMAC()
+ xml = """ + <interface type='network'> + <source network='default'/> + <mac address='%s' > + </interface> + """ % mac
should I gurantee that the MAC address generated is unique by myself? check every interface mac of every guest, and make sure no address clashing?
Yes, exactly. You may be trying how the systems behave when MAC addresses clash, you may have different subnets which are not connected and you want have the same MAC address, but libvirt will never know if you want to connect them together, you may have two machines defined with slight differences (one with numa one without) and run the one you want each time, etc. And libvirt can't possibly know about this. IIRC, virt-manager can do the thing you want, but that's probably not applicable for you, so you'll have to go through the list of VMs you don't want the addresses to clash and check whether the MAC is ok or not. Or assign a MAC using a function according to some unique element of yours and you don't have to check anything.
I wonder can libvirt support a API to generate mac address?
Patches are welcome :-) Martin
Martin
void virMacAddrGenerate(const unsigned char prefix[VIR_MAC_PREFIX_BUFLEN], virMacAddrPtr addr) { addr->addr[0] = prefix[0]; addr->addr[1] = prefix[1]; addr->addr[2] = prefix[2]; addr->addr[3] = virRandomBits(8); addr->addr[4] = virRandomBits(8); addr->addr[5] = virRandomBits(8); } libvirt also use the KVM prefix as default as it's in the privately administered range: 52:54:00:XX:XX:XX
-- Thanks and best regards!
Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
-- Thanks and best regards!
Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
On Fri, Jan 24, 2014 at 04:34:12PM +0800, Sheldon wrote:
On 01/24/2014 03:55 PM, Martin Kletzander wrote:
On Fri, Jan 24, 2014 at 10:37:20AM +0800, Sheldon wrote:
Now I working on a new KVM management tool base on html5 and libvirt
we will support a REST API for detach and attach guest interface.
we want to use mac as the identifier of the network interface.
That meas we should get the mac after the user create a interface. also other people may be doing the exact same thing at the exact same time to create a interface.
Here are the demo codes:
dom = self._get_vm(vm) xml = """ <interface type='network'> <source network='default'/> </interface> """ dom.attachDeviceFlags(xml, libvirt.VIR_DOMAIN_AFFECT_CURRENT) # now I want to get the mac, how to get it?
You have to parse the XML back and find it.
I have check libvirt use this code to generate a mac address. does libvirt can gurantee that the MAC address generated is unique?
No, as mentioned in the second subthread, the XML you provided is incomplete and can cause address clashing.
So te best answer to your question in $SUBJ would be "generate it yourself and add it to the XML before attaching".
now I define a mac address generator in our management tool. it will generate a mac and assign it xml before create the interface.
+ def randomMAC(): + mac = [0x52, 0x54, 0x00, + random.randint(0x00, 0x7f), + random.randint(0x00, 0xff), + random.randint(0x00, 0xff)] + mac = randomMAC()
+ xml = """ + <interface type='network'> + <source network='default'/> + <mac address='%s' > + </interface> + """ % mac
should I gurantee that the MAC address generated is unique by myself? check every interface mac of every guest, and make sure no address clashing?
Yes, exactly. You may be trying how the systems behave when MAC addresses clash, you may have different subnets which are not connected and you want have the same MAC address, but libvirt will never know if you want to connect them together, you may have two machines defined with slight differences (one with numa one without) and run the one you want each time, etc. And libvirt can't possibly know about this. IIRC, virt-manager can do the thing you want, but that's probably not applicable for you, so you'll have to go through the list of VMs you don't want the addresses to clash and check whether the MAC is ok or not. Or assign a MAC using a function according to some unique element of yours and you don't have to check anything.
I wonder can libvirt support a API to generate mac address?
Patches are welcome :-)
On 01/24/2014 05:30 PM, Martin Kletzander wrote: libvirt.virDomain.macAddrGenerate() or libvirt.virConnect.macAddrGenerate() ?
Martin
Martin
void virMacAddrGenerate(const unsigned char prefix[VIR_MAC_PREFIX_BUFLEN], virMacAddrPtr addr) { addr->addr[0] = prefix[0]; addr->addr[1] = prefix[1]; addr->addr[2] = prefix[2]; addr->addr[3] = virRandomBits(8); addr->addr[4] = virRandomBits(8); addr->addr[5] = virRandomBits(8); } libvirt also use the KVM prefix as default as it's in the privately administered range: 52:54:00:XX:XX:XX
-- Thanks and best regards!
Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
-- Thanks and best regards!
Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
-- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
-- Thanks and best regards! Sheldon Feng(冯少合)<shaohef@linux.vnet.ibm.com> IBM Linux Technology Center
On Sat, Jan 25, 2014 at 12:06:10AM +0800, Sheldon wrote:
On Fri, Jan 24, 2014 at 04:34:12PM +0800, Sheldon wrote:
On 01/24/2014 03:55 PM, Martin Kletzander wrote:
On Fri, Jan 24, 2014 at 10:37:20AM +0800, Sheldon wrote:
Now I working on a new KVM management tool base on html5 and libvirt
we will support a REST API for detach and attach guest interface.
we want to use mac as the identifier of the network interface.
That meas we should get the mac after the user create a interface. also other people may be doing the exact same thing at the exact same time to create a interface.
Here are the demo codes:
dom = self._get_vm(vm) xml = """ <interface type='network'> <source network='default'/> </interface> """ dom.attachDeviceFlags(xml, libvirt.VIR_DOMAIN_AFFECT_CURRENT) # now I want to get the mac, how to get it?
You have to parse the XML back and find it.
I have check libvirt use this code to generate a mac address. does libvirt can gurantee that the MAC address generated is unique?
No, as mentioned in the second subthread, the XML you provided is incomplete and can cause address clashing.
So te best answer to your question in $SUBJ would be "generate it yourself and add it to the XML before attaching".
now I define a mac address generator in our management tool. it will generate a mac and assign it xml before create the interface.
+ def randomMAC(): + mac = [0x52, 0x54, 0x00, + random.randint(0x00, 0x7f), + random.randint(0x00, 0xff), + random.randint(0x00, 0xff)] + mac = randomMAC()
+ xml = """ + <interface type='network'> + <source network='default'/> + <mac address='%s' > + </interface> + """ % mac
should I gurantee that the MAC address generated is unique by myself? check every interface mac of every guest, and make sure no address clashing?
Yes, exactly. You may be trying how the systems behave when MAC addresses clash, you may have different subnets which are not connected and you want have the same MAC address, but libvirt will never know if you want to connect them together, you may have two machines defined with slight differences (one with numa one without) and run the one you want each time, etc. And libvirt can't possibly know about this. IIRC, virt-manager can do the thing you want, but that's probably not applicable for you, so you'll have to go through the list of VMs you don't want the addresses to clash and check whether the MAC is ok or not. Or assign a MAC using a function according to some unique element of yours and you don't have to check anything.
I wonder can libvirt support a API to generate mac address?
Patches are welcome :-)
On 01/24/2014 05:30 PM, Martin Kletzander wrote: libvirt.virDomain.macAddrGenerate() or libvirt.virConnect.macAddrGenerate() ?
I'd say it depends on what you want it to do. If you want it *only* to generate the mac address, then I see no point in exposing it; that'd be like exposing a STRPREFIX macro :) Martin
participants (3)
-
Jincheng Miao -
Martin Kletzander -
Sheldon