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--- unix:virtualization:virtlib:quickreference [2022/07/19 19:17] – rodolico
+++ unix:virtualization:virtlib:quickreference [2022/10/31 23:12] – c/libvirt/ rodolico
@@ Line 1: / Line 1: @@
 ====== virt-lib Quick Reference ======
+virtlib stores its configuration for each //domain// (virtual) in /etc/libvirt/qemu*.xml. You should not manually modify anything in this directory, but you can safely do any read-only operation. To edit/export/whatever, the //virsh// command has several options that will help you out.
+The xml files are, well, xml. The format is documented at https://libvirt.org/formatdomain.html which is guaranteed to either help you, or put you to sleep.
 ===== virt-top =====
@@ Line 37: / Line 41: @@
 This is actually not intuitive. I'm going to describe how to do this from a pretty complex setup with no GUI; adjust as needed. In this case, we need to boot the virtual myvirt from a gparted cdrom image located in /media/isos/gparted-live-1.3.0-1-amd64.iso so we can modify the partitions. However, we did not have a cdrom image for the installation, so one has not been created.
-Both assume the virtual has been turned of <code bash>virsh shutdown myvirt</code>
+Both assume the virtual has been turned off <code bash>virsh shutdown myvirt</code>
-===== without editing configuration =====
+Some people do not want to manually edit the XML used to configure the virtuals, others prefer it. Some things, like setting a boot menu with a realistic timeout appear to require it; I have not found a way to do it through the virsh command.
-First, see if there is a cdrom installed. One simple way is to dump the xml and grep for cdrom
-<code bash>virsh dumpxml myvirt | grep cdrom</code>
-Once this is done and you have a cdrom, you should be able to tell which one it is with
-<code bash>virsh domblklist myvirt</code>
-which shows the block devices attached to myvirt.
-===== I"m not afraid to edit the config =====
+I use the --config flag a lot. If you use this flag, any changes you make are written to the config file and will persist across boots.
+=== without manually editing configuration ===
+  - First, see if there is a cdrom installed. One simple way is to dump the xml and grep for cdrom<code bash>virsh dumpxml myvirt | grep cdrom</code>
+  - Once this is done and you have a cdrom, you should be able to tell which one it is with<code bash>virsh domblklist myvirt</code> which shows the block devices attached to myvirt.
+  - Mount your image on the CDROM
+    - If you have one and you know which drive it is<code bash>virsh change-media dd-113-virt hdb /media/xen-store/isos/gparted-live-1.3.0-1-amd64.iso --insert --config</code>This is assuming the drive was hdb
+    - If you do not have a CDROM, use<code bash>virsh attach-disk myvirt /media/xen-store/isos/gparted-live-1.3.0-1-amd64.iso hdb --driver file --type cdrom --mode readonly --config</code>This assumes hdb did not show up as used in your domblklist above.
+=== I'm not afraid to edit the config ===
   - Edit the config file with <code bash>virsh edit myvirt</code>
   - Look for something like //<disk type='file' device='cdrom'>//
@@ Line 54: / Line 62: @@
     - This will enable the boot menu, and have a wait of 5 seconds (5000 milliseconds) for you to choose.
   - If you want, change the boot order by adding <code xml><boot dev='cdrom'/></code> //above// the boot entry if it is not already set.
+=== Starting the virtual ===
+  - Start the virtual with <code bash>virsh start myvirt</code>
+  - Immediately make the VNC connection (if you followed the manual edit, you have 5 seconds)
+  - When prompted, press ESC to choose the CDROM drive (assuming you didn't set it as the default)
+=== Cleanup ===
+Do the following if you want to remove the CDROM when you're done. Note: this is likely required if you set the CDROM as the primary boot device.
+<code bash>virsh change-media myvirt hdb --eject --config</code>
@@ Line 238: / Line 254: @@
 In my case, I had built a Windows domain without using virtio, and I wanted to change it. This was actually the simplest way I found to do it.
-==== Links ====
+===== Naming Network Links =====
+to give a domain interface a static name when it is run, you can add the following to the interface definition.
+<code xml><target dev='dom113'/></code>
+NOTE: the name must not begin with 'vnet', 'vif', 'macvtap', or 'macvlan', which are prefixes reserved by libvirt and certain hypervisors. See
+https://libvirt.org/formatdomain.html#overriding-the-target-element
+<code xml>
+   <interface type='bridge'>
+      <mac address='00:16:3e:6b:f4:da'/>
+      <source bridge='br_lan'/>
+      <target dev='dom113'/>
+      <model type='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </interface>
+</code>
+You can now do things like <code bash>ifconfig dom113</code> or <code bash>ip a show dom113</code>
+===== Links =====
   * https://www.caretech.io/2017/10/18/converting-windows-vm-hard-disk-interface-to-virtio-with-proxmox-ve-5/
@@ Line 245: / Line 280: @@
   * https://serverfault.com/questions/672253/how-to-configure-and-use-qemu-guest-agent-in-ubuntu-12-04-my-main-aim-is-to-get#691616
   * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/virtualization_administration_guide/sect-qemu_guest_agent-running_the_qemu_guest_agent_on_a_windows_guest
+  * https://libvirt.org/formatdomain.html