Update of "Concepts"
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Artifact ID: 4cb8c5829f11889a2d655e252af46004c8c87bb0
Page Name:Concepts
Date: 2017-01-14 16:04:59
Original User: vitus
Mimetype:text/x-markdown
Parent: 7768da8a2ee0a485678d7f9605657a33898191d4 (diff)
Content

Concepts

Use vws script.

Although there is start script in the directory of virtual machine, which is theoretically can be used to start machine without vws script, most operations witb virtual workstations should be done via vws.

You can edit start script direcrtly and add options vws doesn't know about yet, but it should be done with care - vws might parse and edit this script. We would take as much care as we can to preserve user modifications.

There are also things in the start script which should be kept intact or vws would be unable to perform some operations - such as attach cdrom on start.

Note that vws start command is able to pass arbitrary qemu optyions.

If you want to send commands to qemu monitor, preferrable way to do so is

vws monitor

command. It interacts nicely with other qemu commands, so you can be sure that if you use some vws command while monitor is open, it would not break things.

Start brings you GUI

By default, if user have DISPLAY variable defined, vws start command starts spice client. If it finds, that machine is already running, it just starts the client, If not, it starts machine and than client.

So vws start machine actually means «I want console of this virtual machine on this screen».

Console is set of devices

When you connect to console of virtual machine, you get not only picture on your screen and ability to send keyboard and mouse events. By default, vws virtual machines have emulated sound card and sounds are forwarded to client. Also by default, at least one USB device on the client machine can be redirected to VM. When vws usb command operates with server devices, i.e. devices on machine where VM is running, spice-client allows to redirect devices from the machine where user sits.

Remote access

By default, vws virtual machines listen for spice connection on loopback interface only. Of course, you always can use ssh port forwarding if you want to access spice GUI of machine, you've not started for remote use.

But if you start machine with environment SPICE_PASSWORD defined, it binds to all interfaces and allows access to anybody who knows this password.

Option --password for vws start command does this. But it cannot change configuration of already started machine. If qemu monitor allows to change password interactively, it doesn't allow to change list of interfaces spice server listen on.

If you want some machine to always start in the network-accessable mode, you can define SPICE_PASSWORD directy in the machine's start script. It is only way to allow network access for autostart VMs.

Personal and shared VMs

vws supports personal and shared VMs. By default, vws create creates personal vm in the ~/VWs. If you want to create shared VM, use --shared option.

~/VWs may be symlink to another partition where there is enough space for virtual machines.

If you want to share already created VM, just move it to shared VMs directory, as specified in /etc/vws.conf and chgrp it to vm_group (as specified in the same file). You should be able to do so without superuser rights, because shared VM directory should be writable to vm_group (if vws is properly set up) and you must be member of this group to use kvm at all.

VMs are created group writable anyway, both shared and personal. It does no harm to have personal VMs group-writable, because modern Linuxes have personal group for each user.

Autostart VMs

Sometimes it is desirable that some VMs start upon system bootup. In vws autostart VMs are considered shared.

/etc/vws.conf lists two directories for shaed vms SharedVMs and AutostartVMs. VMs in first directory should be started explicitely one by one using vws start command.

VMs in the second one are started at once by vws autostart.

vws distribution provides init.d script for system V init and service file for systemd, to autostart machines.

Note that there also is vws shutdown command which tries to stop any running VM it finds - shared or personal, autostarted or not.

Creating Virtual Machines

There are reasonable defaults for almost all machine parameters in the

/etc/vws.conf
. So, you just speciy those parameters you want to change.

Importing images from other systems

VM in vws consists of at least disk image and start script. So, if you want to use VM disk image created by some other virtualization system (virsh, oVirt, VirtualBox, VMWare), you have to create VM from existing image.

Just specify your image in the --image option of create command, and it would be converted from its original format to qemu qcow2 format and start file would be written.

Creating VMs by installation from ISO image

If you specify ISO image via --install option to vws create, newly created virtual machine would be started immediately and given image attached to its virtual CD-ROM drive, so installation process starts.