From: Richard W.M. Jones <rjones@redhat.com>
Date: Mon, 14 Nov 2022 08:59:36 +0000 (+0000)
Subject: Talk about using virt-v2v in Kubevirt
X-Git-Url: http://git.annexia.org/?a=commitdiff_plain;h=65b3746ea784e2a089b992d6fe234fa232e25b24;p=libguestfs-talks.git

Talk about using virt-v2v in Kubevirt
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+Virt-v2v in Kubevirt
+====================
+
+(0) What is it
+
+Convert a virtual machine from VMware (usually) to run on KVM.
+Involves installing the correct device drivers inside the guest
+and making many other changes so it is bootable.
+
+Supports Windows and some Linux distros.
+
+First version of virt-p2v was written in 2007(!)  We've been
+serious about it since about 2008/2009.
+
+
+(1) Virt-v2v is a process, not a step
+
+Many different types of inputs supported:
+
+* VMware over HTTP
+
+* VMware over VDDK
+
+* VMware over SSH
+
+* Xen
+
+* local disk files
+
+* OVA files (GUI export or ovftool)
+
+* local VMX files
+
+* libvirt
+
+* from physical machines (p2v*)
+   *slightly different process
+
+Command line is complicated, but stick to the documentation and
+you'll be fine.
+
+
+(2) Correctness, supportability
+
+For a correct conversion, it's vitally important that we query
+VMware for the full metadata, and also vital that the metadata
+that virt-v2v writes is consumed by the target hypervisor.
+
+Metadata == VMware VMX data on the input side
+         == Kubevirt YAML on the output side
+
+Virt-v2v already knows how to do this, and also how to efficiently
+copy the guest.  There are many complex corner cases.
+Don't duplicate this work.
+
+We only support virt-v2v when used as directed.
+
+I'm the one who does third line support when things go wrong.
+
+I've been in several "difficult" calls with customers
+when we've fucked up over the years, and I'm not keen on being
+on any more.
+
+
+(3) What we've tried
+
+Modified Tomas's example volume populator
+(https://github.com/nyoxi/vmware-populator) so that it just runs
+virt-v2v.
+
+=> Ugly having to pass virt-v2v args
+
+   * could be cleaned up with some CRDs
+
+=> Only a single disk supported
+
+=> No place to write out the metadata
+
+=> Have to specify the size up front
+
+=> How to report errors?
+
+=> Possible we could use a filesystem PVC and write out:
+
+    * disk1.qcow2
+    * disk2.qcow2
+    * guest.yaml
+    * virt-v2v.log
+
+   but would involve an extra copying step (or else modifying
+   Kubevirt to be able to boot from this).
+
+   * The main point about reducing copies is reducing *remote* copies
+     because VDDK is expensive and finnicky.  Local copies of fully
+     sparsified data within the target cluster may be acceptable for a
+     first pass.
+
+
+(4) What we also talked about
+
+Could we just run virt-v2v in a pod?
+
+=> It would do the conversion and run kubectl / virtctl commands
+   in order to create resources and the final guest as needed.
+
+=> Cannot create PVCs
+
+Can we chain pods together?
+
+=> One pod sets up the PVCs, second pod does the conversion and
+   finishes up.
+
+I feel we are missing some "automation" thing in Kubernetes.
+Is this what operators are?
+
+
+(5) Miscellaneous
+
+We have an "-o kubevirt" output mode which generates Kubevirt YAML.
+It's not upstream, but could be once we've decided what to do.
+
+If we decide that some other process must create the PVC(s) in
+advance, then virt-v2v needs a way to estimate the number/size
+of disks needed.  (We had this in the past and removed it, but
+could add something again once it's clear what is exactly needed.)