Nikita Tokarchuk

Hello! Ny name is
Nikita Tokarchuk

I'm a Hacker on its true meaning. Simply saying a computer technology enthusiast.
I focus my interests on backend engineering in all ones kind.
From 2017 and continuing nowadays I use Golang at most.

Feel free to check my CV: Download PDF

I started to grow as a professional in 2012 and since that time I've solved a huge amount of business problems by using several technologies:

  • by using JavaScript and NodeJS I used to make highload backends and fancy web apps;
  • used a lot of C++ for making highload backends as well as efficient apps for embedded projects;
  • configured tons of GNU/Linux based servers together with OSsoftware with the help of ansible;
  • helped to store incredible amount of data in different databases such as MongoDB and *SQL;
  • collected millions of metrics and clicks in ClickHouse what were proceed through either Kafka or RabbitMQ;
  • run and used a variety of kubernetes setups from bare-metal to EKS;
  • deployed some amount of helm charts with the help of tiller and then without one;
  • saved a lot of money with the well planned configuration in GCP and AWS;
  • automated boring routine with the help of Jenkins and GH Actions;
  • and more...

See some myown OSS projects on my git:

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quay docker image for linux/arm64

there is no official linux/arm64 quay image at the moment

Yes, quay is being built for linux/ppc64le in addition to a «default» linux/amd64 one.

ok, solution

I've started building a multiplatform quay docker image that supports both linux/amd64 and linux/arm64. Nothing custom but just an image. This runs natively on arm64 now.

So if you need one, pull it:

docker pull

This is a place where builds are happening:

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how to create EFI-compatible rhel installation usb


RedHat provides several ISO images that let you install a system. They are DD compatible and one can flash an ISO into USB drive by using either DD or Fedora Media Writer.

If you are lucky enough you may boot this USB in a BIOS-legacy mode, but not in the EFI mode. The installation also continues in BIOS-legacy and doesn't create any EFI-compatible partitions. No secure boot at all.

For those who care about UEFI in their system there are no structured information on RedHat docs.

see into an image

An official ISO has a both isolinux bootloader (bios-mode) and grub (efi-mode). The latter one disappear when you DD the image to USB drive. It may be just because of some misconfiguration during the ISO creating process. I tried to repack an ISO but had no luck about EFI mode.

efi-mode easy way

EFI boot was desinged to be very simple. There are no hidden magic stuff (almost) behind the bootloader. EFI-enabled partitions is just a VFAT-formatted partition with a custom PART-GUID. There are some limitations about the size and some others between different platforms, but let's keep it simple for now.
EFI partitions has type code «EF00» and PART-GUID «C12A7328-F81F-11D2-BA4B-00A0C93EC93B».

GPT fdisk (gdisk) version 1.0.9

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): p
Disk disk.raw: 3104768 sectors, 1.5 GiB
Sector size (logical): 512 bytes
Disk identifier (GUID): 2A2619EB-3FA6-4C34-A716-1DCA94AD43B7
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 3104734
Partitions will be aligned on 2048-sector boundaries
Total free space is 4029 sectors (2.0 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         3102719   1.5 GiB     EF00  EFI system partition

Command (? for help): x

Expert command (? for help): i
Using 1
Partition GUID code: C12A7328-F81F-11D2-BA4B-00A0C93EC93B (EFI system partition)
Partition unique GUID: 2A1143B9-AFE9-48CE-8B47-21535F031770
First sector: 2048 (at 1024.0 KiB)
Last sector: 3102719 (at 1.5 GiB)
Partition size: 3100672 sectors (1.5 GiB)
Attribute flags: 0000000000000000
Partition name: 'EFI system partition'

gdisk util makes everything simple. To prepare an EFI-compatible partition you need to set the type to «EF00» during the creating process, then PART-GUID will be filled automatically:

Command (? for help): n
Partition number (1-128, default 1):
First sector (34-3104734, default = 2048) or {+-}size{KMGTP}:
Last sector (2048-3104734, default = 3102719) or {+-}size{KMGTP}:
Current type is 8300 (Linux filesystem)
Hex code or GUID (L to show codes, Enter = 8300): ef00
Changed type of partition to 'EFI system partition'

almost it

Let's mount everything we need to make it work. First, locate an RedHat installation ISO, e.g. «rhel-baseos-9.0-x86_64-boot.iso». Then locate a newly created EFI partition, e.g. «/dev/sdc1».

$ realpath rhel-baseos-9.0-x86_64-boot.iso
$ stat /dev/sdc1
  File: /dev/sdc1

EFI partition needs to be formatted first, please notice a «label» argument «-n RHEL9». This is necessary for the bootloader to find a boot root partition by label.

# sudo mkfs.fat -F 32 -n RHEL9 /dev/sdc1
mkfs.fat 4.2 (2021-01-31)

Now mount everything. Be aware of ephemeral directory I use in exmaples, do not copy them blindly.

# mktemp -d --suffix=-iso-mount

# mktemp -d --suffix=-efi-mount

# mount -o loop /home/mainnika/rhel-baseos-9.0-x86_64-boot.iso /tmp/tmp.SR9TpfSV5U-iso-mount
mount: /tmp/tmp.SR9TpfSV5U-iso-mount: WARNING: source write-protected, mounted read-only.

# mount /dev/sdc1 /tmp/tmp.A7IJSAwhHy-efi-mount

# mount
/home/mainnika/rhel-baseos-9.0-x86_64-boot.iso on /tmp/tmp.SR9TpfSV5U-iso-mount type iso9660
/dev/sdc1 on /tmp/tmp.A7IJSAwhHy-efi-mount type vfat

Prepare/copy EFI bootloader. The EFI bootloader is just a «EFI» folder located in root.

# cp -r /tmp/tmp.SR9TpfSV5U-iso-mount/EFI /tmp/tmp.A7IJSAwhHy-efi-mount

For some weird reason there is an invalid bootloader in EFI folder, «BOOTX64.EFI». Let's replace it with grub which is right there as well and remove some of leftovers.

# mv /tmp/tmp.A7IJSAwhHy-efi-mount/EFI/BOOT/grubx64.efi /tmp/tmp.A7IJSAwhHy-efi-mount/EFI/BOOT/BOOTX64.EFI
# rm /tmp/tmp.A7IJSAwhHy-efi-mount/EFI/BOOT/mmx64.efi

The most important step is to change a «grub.cfg» and let him use right paths and kernel. You might see here the «label» we've used during formatting.

# sed -i 's/RHEL-9-0-0-BaseOS-x86_64/RHEL9/g' /tmp/tmp.A7IJSAwhHy-efi-mount/EFI/BOOT/grub.cfg
# sed -i 's/images\/pxeboot/isolinux/g' /tmp/tmp.A7IJSAwhHy-efi-mount/EFI/BOOT/grub.cfg

The last step is to copy installation files from ISO media to EFI partition.

# cp -r /tmp/tmp.SR9TpfSV5U-iso-mount/{images,isolinux} /tmp/tmp.A7IJSAwhHy-efi-mount

that's it

Examine a filesystem tree for the EFI partition.

# tree /tmp/tmp.A7IJSAwhHy-efi-mount/
├── EFI
│   └── BOOT
│       ├── BOOTX64.EFI
│       ├── fonts
│       │   └── unicode.pf2
│       └── grub.cfg
├── images
│   ├── efiboot.img
│   └── install.img
└── isolinux
    ├── boot.msg
    ├── grub.conf
    ├── initrd.img
    ├── isolinux.bin
    ├── isolinux.cfg
    ├── ldlinux.c32
    ├── libcom32.c32
    ├── libutil.c32
    ├── memtest
    ├── splash.png
    ├── vesamenu.c32
    └── vmlinuz

Unmount everything and eject USB drive,

# umount /tmp/tmp.SR9TpfSV5U-iso-mount /tmp/tmp.A7IJSAwhHy-efi-mount
# sync
# eject /dev/sdc

then boot it!

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stream coding process to discord using OBS

Nowadays code streaming become more popular. There is even Twitch channel with software developing.

Usually for the streaming people use OBS software. Basically it allows you to combine several video/audio/etc sources into the one scene that is being streamed to the service.

Discord is another super popular app. The app let people be connected inside some community. For example the group of graphic illustrators can share their works and discuss in voice chats.

Discord live streaming is not very popular but sometimes can be increadibly useful. But Discord doesn't support custom streaming at the moment and the only choice you have is to stream window or entire screen.

a couple of tiny tricks

I use OBS Studio from the website It is free and open-source!

Let's take a look!

image capture

First I move all controls into floating windows by using «windowed» button at the left of the control:

Now all your controls are separated and floating under the main window. You may want to adust its properties and size to fill the window with the scene:

That's all! The main OBS window can be a source for the discord live stream:

Go live!


Using window source Discord takes sound from the window as well.
By enabling sound monitoring we make the window emit sound that will be captured.
The tricky part here is to avoid loops in the sound. But this part is hardly depends on your requirements and hardware.

As the simple solution to capture everything I can hardly recommend VB-Cable app that is basically a pipe source-sink. See for details.

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