Wednesday, July 3, 2019

Scalable Jenkins with Kubernetes cluster

I wrote a short tutorial on GitHub about creating a scalable Jenkins on a Kubernetes cluster. The main pod is the master which creates slave pods per need and then deletes those pods when they are no longer needed.
You can find the tutorial at the same GitHub repo here:

Friday, March 11, 2016

VSphere | Advanced snapshot trobuleshooting - Part 3 - Example: Invalid snapshot configuration

Unable to consolidate because of invalid snapshot configuration

This is Part 3 of the short tutorial series:
vSphere | Advanced snapshot troubleshooting

This is much more advanced than our previous example.  You will see these two errors if you attempt to consolidate, clone or migrate the VM:

Detected and invalid snapshot configuration


... vmdk was not found

VSphere | Advanced snapshot trobuleshooting - Part 2 - Example: Unable to consolidate because the file is locked

This is Part 2 of the short tutorial series:
vSphere | Advanced snapshot troubleshooting

Virtual Machine consolidation attempts result with bellow error:
Unable to access file since it is locked

VSphere | Advanced snapshot trobuleshooting - Part 1 - The ESXi shell is your friend

I am writing this article as an extension to my previous post A VM is showing disk size of 0B where I will attempt to make a general explanation on how to troubleshoot and successfully solve snapshots and consolidation problems in your vSphere with a number of examples. Because the general article was so big, I decided to split it into three parts. This Part 1, is where I am describing the commands which are used to solve most of the snapshot problems and in the next two parts I will describe the process of troubleshooting via examples.

Saturday, February 13, 2016

Linux | Don't reboot after adding a new disk on a VM

It is quite common practice when adding a new drive to a Linux system to reboot the system afterwards so that the server can re-scan its hardware and detect the change. However, every now and then we get to make changes to a server that we don't want to reboot it for some reason. Or maybe you are lazy, like me and don't want to wait 1 min to reboot. In any case, bellow is a way to make your system re-scan the hardware and detect the changes.

Thursday, February 4, 2016

Linux | How to search for a particular string in multiple files

Every now and then I find myself into a situation where I have to search for a particular string from a set of files, and every time I have to remind myself again.

As the old proverb says: "The fool remembers, the smart writes down."

That is why I decided to write this down, so that I can come back and find it again.

# grep -rnw '/path/to/somewhere/' -e "pattern"

Here -r or -R is recursive, -n is line number and -w stands match the whole word. We can also add -l (lower-case L) to just give the file name of matching files.

So in my current example, I work on Nagios and I want to find the file containing that check_snmp command i would type:

# grep -rnw '/etc/nagios/objects/' -e 'check_snmp'

Which will produce the output:

/etc/nagios/objects/commands.cfg:147:# 'check_snmp' command definition
/etc/nagios/objects/commands.cfg:149:        command_name    check_snmp

From here we can basically see the file where check_snmp is defined along with the line number of that file.

Extending the command with --include or --exclude parameter we can create neatly commands to also search for files with particular extension. The bellow command will check only .cfg or .conf files.

# grep --include=\*.{cfg,conf} -rnw '/etc/nagios/objects/' -e 'check_snmp'

# grep --exclue=\*.0 -rnw '/etc/nagios/objects/' -e 'check_snmp'

And as always:


# man grep

Tuesday, January 19, 2016

CentOS V2V | Hyper-V to VMware - The easy way

I had a task to export a Hyper-V, CentOS 6 VM and deploy it to a vSphere cluster. Due to the nature of the VM we had to preserve it because the VM was already set up and it was too long for us to build a new one with the same settings.

Before start I would like to point out that if this is a Linux VM you are doing, then because there will be a complete hardware change you may end up with unbootable clone, which can be fixed. This did not happen to me though, but in the end of this article I will also point those things out as potential issues.