Month: December 2019

Live backups with VMWare ESXi, and no vSphere

To make live backups of a guest on an ESXi host’s SSH UNIX shell, you need to utilize the fact that when a snapshot of a VMDK file gets made, the original VMDK file turns so called read-only. Releasing the locks that would otherwise withhold vmkfstools from creating a clone.

This means that if you make a snapshot that you can use vmkfstools of the non-snapshot VMDK files from which the snapshot was made.

Let’s get started scripting this.

GUEST="GUESTNAME"
DISKS="$GUEST EXTRADISK"
SRC=/vmfs/volumes/STORAGE/$GUEST
DST=/vmfs/volumes/STORAGE/backup/$GUEST

First get the VmId:

VMID=`vim-cmd vmsvc/getallvms | grep $GUEST | cut -d " " -f -1`

Create a poor man’s backup snapshot on $GUEST:

vim-cmd vmsvc/snapshot.create $VMID backup poor-mans-backup 0 0

Create the clones of the non-snapshot VMDK files (the one without numbers after $DISK)

mkdir -p $DST
for DISK in $DISKS; do
   vmkfstools -i $SRC/$DISK.vmdk $DST/$DISK.vmdk -d sesparse
done

Now remove the snapshots from $GUEST:

vim-cmd vmsvc/snapshot.removeall $VMID

Now, copy the VMX file:

cp $SRC/$GUEST.vmx $DST/$GUEST.vmx

Alternatively you can use ghettoVCB which is a little program that does the same thing.

Automated provisioning with VMWare ESXi

For a Jenkins environment I had to automate the creation of a lot of identical build agents. Identical up until of course the network configuration. Sure I could have used Docker or what not. But the organization standardized on VMWare ESXi. So I had to work with the tools I got.

A neat trick that you can do with VMWare is to write so called guestinfo variables in the VMX file of your guests.

You can get SSH access to the UNIX-like environment of a VMWare ESXi host. In that environment you can do typical UNIX scripting.

First we prepare a template that has VMWare guest tools installed. We punch the zeros of the vmdk file and all that stuff. So that it’s nicely packaged and quick to make clones from. On the guest you do:

dd if=/dev/zero of=/largefile bs=10M ; rm /largefile

On the ESXi host you do:

vmkfstools --punchzero /vmfs/volumes/STORAGE/template/DISK.vmdk

Now you can for example do this (on the ESXi host’s UNIX environment):

SRC=/vmfs/volumes/STORAGE/template
DST=/vmfs/volumes/STORAGE/auto
mkdir -p $DST/$1

# Don't use cp to make copies of vmdk files. It'll just
# take ages longer as it will copy 0x0 bytes too.
# vmkfstools is what you should use instead
vmkfstools -i $SRC/DISK.vmdk $DST/$1/DISK.vmdk -d thin

# Replace some values in the destination VMX file
cat $SRC/TEMPLATE.vmx | sed s/TEMPLATE/$1/g > $DST/$1/$1.vmx

And now of course you add the guestinfo variables:

echo "guestinfo.HOSTN=$1" >> $DST/$1/$1.vmx
echo "guestinfo.EXTRA=$2" >> $DST/$1/$1.vmx

Now when the guest boots, you can make a script to read those guestinfo things out and let it for example configure itself (on the guest):

#! /bin/sh
HOSTN=`vmtoolsd --cmd "info-get guestinfo.HOSTN"`
EXTRA=`vmtoolsd --cmd "info-get guestinfo.EXTRA"`
if test "$EXTRA" = "provision"; then
   echo $HOSTN > /etc/hostname
   reboot
fi

Some other useful VMWare ESXi commands:

# Register the VMX as a new virtual machine
VIMID=`vim-cmd /solo/register $DST/$1/$1.vmx`

# Turn it on
vim-cmd /vmsvc/power.on $VIMID &

# Answer 'Copied' on the question whether it got
# copied or moved
sleep 2
VMMSG=`vim-cmd /vmsvc/message $VIMID | grep "Virtual machine message" | cut -d : -f -1 | cut -d " " -f 4`
if [ ! -z $VMMSG ]; then
    vim-cmd /vmsvc/message $VIMID $VMMSG 2
fi

That should be all you need. I’m sure we can adapt the $1.vmx file such that the question doesn’t get asked. But my solution with answering the question also worked for me.

Next thing we know you’re putting a loop around this and you just ‘programmed’ creating a few hundred Jenkins build agents on some powerful piece of ESXi equipment. Imagine that. Bread on the table and the entire flock of programmers of your customer happy.

But! Please don’t hire me to do your DevOps. I’ve been there before several times. It sucks. You get to herd brogrammers. They suck the blood out of you with their massive ignorance on almost all really simple standard things (like versioning, building, packaging, branching, etc. Anything that must not be invented here). Instead of people who take the time to be professional about their job and read five lines of documentation, they’ll waste your time with their nonsense self invented crap. Which you end up having to automate. Which they always make utterly impossible and (of course) non-standard. While the standard techniques are ten million times better and more easy.

I just hacked my Lay Z Spa’s water flow sensor

Yesterday I fixed my Bestway Lay Z Spa. It gave the infamous E02.

Opening up the thing it was. Because in a video the guy explained about the water flow sensor being a magnetic switch I decided to try taking the sensor itself out of the component. Then I tried with a external magnet to get the detached switch to close. The error was gone and I could make the motor run without any water flowing. That’s probably not a great idea if you don’t want to damage anything. So, of course, I didn’t do that for too long.

However. When I reinserted the sensor into the component, and closed the valve myself, the ER02 error did still happen. I figured the magnet that gets pushed to the ceiling of the component was somehow weakened.

Then I noticed a little notch on it. I marked it in a red circle:

I decided to take a flat file and file it off. When I now closed the valve myself, I could just like with the magnet make the motor run without any water flowing.

I reassembled it all. Reattached the device to the bath tube. It all works. Warm water this evening! I hope there will be stars outside.

Jeff Hoeyberghs laat een scheet

Het land in crisis: alle hoofdredacteuren van het land schrijven opiniestukken!

Honderden vrouwen naar de rechtbank. Christine Mussche fantaseert zich al rijk: driehonderd keer een factuur van een paar duizend Euro! Dat is een villa. Dat zal vast een vruchtgebruik worden. Want haar kuuroord voor misnoegde vrouwen kan nadien nog omgetoverd worden in een sauna- en massagesalon of een heus bedevaartsoord voor het Belgisch feminisme.

Met wat mevrouw de advocaat er waarschijnlijk aan gaat verdienen hadden we er ook een begrotingstekort van een gemiddeld groot dorp mee kunnen oplossen, er een school of een typisch gemeentelijk zwembad mee kunnen bouwen.

Meanwhile: we hebben ook al maanden geen regering. Nobody cares.