[WSL2/Win10] virt-manager for kvm on Windows

kvm Virtualisiation is great, however, useable tools to create and manage said VMs are rare. The best tool for the job, virt-manager is only available for Linux machines. But what if you want to manage said VMs also via Windows 10? WSL2 to the rescue: Just install WSL2 as shown by the excellent Microsoft Guide, install i.e. a Debian/GNU Linux instance and then launch into it.

You should update the instance to the latest version first:

sudo apt update && sudo apt upgrade -y && sudo apt dist-upgrade -y

then you can install virt-manager

sudo apt install -y virt-manager ssh-askpass

the last thing you would need is to install an X server on your windows machine, i.e. Xming or MobaXterm (which contains Xming) and launch it. Then you need to setup the X forwarding in your WSL2 instance, by entering

export DISPLAY="grep nameserver /etc/resolv.conf | sed 's/nameserver //':0"
export DISPLAY="sed -n 's/nameserver //p' /etc/resolv.conf:0"
export DISPLAY=$(ip route|awk '/^default/{print $3}'):0.0

after that, you can launch virt-manager by entering

virt-manager

and configure it to connect to your KVM instance via SSH.

Ubuntu 20.04 Update bricked KVM Virt

I updated an older Ubuntu 18.04 LTS system to the latest LTS and had (among other things) Docker and KVM installed. KVM is actually quite nice if you "just need" a small VM (pfsense ;)). I actually prefer Proxmox and ESXi, but hey, the right tool for the right job.

After the upgrade to 20.04, kvm did not work anymore and I got a lot of lvm2 errors during apt update / apt upgrade sessions, so a short google later I found this. I was a bit nervous, but the fix did neither hurt my kvm nor my Docker instances

sudo apt purge lvm2 && sudo apt install lvm2

(The fix is deleting and reinstalling lvm2)

After reinstalling lvm2, I could successfully execute a virsh list and got my list of running KVM machines back:

 Id   Name      State
-------------------------
 1    pfsense   running

[Win10] Random ports blocked while using Docker / WSL / HyperV

I have been using Windows Subsystem for Linux (WSL) and Docker on my Laptop since a long time. And during last Docker Con, WSL 2 was released to which I switched instantly - which I did not regret.

(Note: Upgrading to WSL 2 and the native Docker for WSL 2 version will cost you your containers and Docker images, there is even a Thanos meme coming around - so I have to give this fair warning ;))

However: Said Laptop started acting strange as suddenly local MariaDB instances or Apache2 did cease to work and even some nodeJS projects on port 9000. All these ports were not taken directly by any application, but somehow it did not work anymore. It turns out that a faulty HyperV update led to the hypervisor reserving too many ports across the board.

Luckily there is a solution to correct this issue as shown here by Christopher Pietrzykowski.

To make it easy and fast: Open up a powershell or cmd prompt as admin user and enter

netsh int ipv4 show dynamicport tcp
netsh int ipv6 show dynamicport tcp

If it comes up with startport 1025 and a huge number of reserved ports, you are experiencing the same problem. Please enter these commands to realign the startport to 49152 for both IPv4 and IPv6

netsh int ipv4 set dynamic tcp start=49152 num=16384
netsh int ipv6 set dynamic tcp start=49152 num=16384

after a reboot, everything should be fixed again 🙂

Bash for sending and receiving raw IP packets

I stumbled across this feature during my bachelor studies:

echo "Hello World" > /dev/tcp/127.0.0.1/5000
echo "Hello World" > /dev/udp/127.0.0.1/5000

You need to be root (obviously) and its supported in bash environment - but not on all systems. You can also cat on the ports and use dns adresses. Its neat to just get a byte out :).

And if you need something more sophisicated, be sure to use the good old netcat ("nc")

Quickly check python imports

If you happen to write a lot of python scripts and just want to check which of the added "imports" are actually needed to function - and do not want to use an IDE - just check out https://pypi.org/project/importchecker/ - it comes down to a quick 

easy_install importchecker

and afterwards you can check your scripts by using

importchecker myScript.py

It will only output the imports NOT needed, which you can then remove by hand

Upgrade SonarQube 6.7 to 7.9

That was surprisingly easy: Just swaped the "sonarqube:6.7-community" for the "sonarqube:7.9-community" image entry in my docker-compose.yml and restarted the Docker container. Upon boot, the container restarted due to an error:

ERROR: [2] bootstrap checks failed
[1]: max file descriptors [4096] for elasticsearch process is too low, increase to at least [65535]
[2]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]

This could be resolved by executing sudo sysctl -w vm.max_map_count=262144 on my Ubuntu 18.04 LTS / Docker Host. After another restart of the container, it worked and I could start the update using a webbrowser under http://IP:9000/setup

(also add the option vm.max_map_count=262144 to the /etc/sysctl.conf)

[Paper] apex: A new commercial off-the-shelf on-board computer platform for sounding rockets

In order to supersede the aging Microchip ATMEGA328P as the de facto standard for Commercial off-the-shelf (COTS) On-Board Computers (OBCs) with a more powerful system for different kinds of high-speed sensors and image acquisition applications, we developed advanced processors, encryption, and security experiment (apex). The platform consisting of a newly developed OBC using COTS components has been flight tested during the ATEK/MAPHEUS-8 sounding rocket campaign. The main advantages of the apex OBC lies in the speed and simplicity of the design while maintaining operational security with a redundant master-master microcontroller system, as well as dual flash storage within each master. Additionally, a single board computer with a containerized and failure-resistant Operating System (OS) (balenaOS) was included to allow usage of a high-definition camera or other more compute-intensive tasks. The bench and flight tests were performed successfully and already showed feasible ways to further improve operational performance.

Published by "American Institute of Physics" (AIP) in "Review of Scientific Instruments" ( ISSN: 0034-6748 / DOI: 10.1063/1.5118855 )

Download (Paper): DLR Elib

Watch Video of flight on Youtube

Release on balena.io Blog (09.10.2019)

Release on Hackaday (11.10.2019)

Release on thenewstack.io (03.11.2019)

balena in Space Talk (11.06.2021)

2nd generation apex Mk.2/Mk.3 studies

SonarQube 6.7 Community with Postgres 9.6 in Docker on Ubuntu

This is a very quick install for SonarQube on Ubuntu 18.04 LTS. I presume you got the latest Docker CE 18.09 and docker-compose 1.24 installed.

# create folders for sonarqube files and postgres
sudo mkdir -p /var/sonarqube/{conf,data,logs,extensions}
sudo chown -R 999:999 /var/sonarqube
sudo mkdir -p /var/sonarqube/postgres
# make folder for all Docker files in home
mkdir ~/sonarqube
cd sonarqube
# create docker-compose.yml with following content
version: '3.1'
services:
  db:
    image: postgres:9.6-alpine
    restart: unless-stopped
    volumes:
      - /var/sonarqube/postgres:/var/lib/postgresql/data
    environment:
     - POSTGRES_USER=sonar
     - POSTGRES_PASSWORD=sonar

  sonarqube:
    image: sonarqube:6.7-community
    ports:
      - 9000:9000
      - 9092:9092
    restart: unless-stopped
    volumes:
      - /var/sonarqube/conf:/opt/sonarqube/conf
      - /var/sonarqube/data:/opt/sonarqube/data
      - /var/sonarqube/logs:/opt/sonarqube/logs
      - /var/sonarqube/extensions:/opt/sonarqube/extensions
    environment:
      - SONARQUBE_HOME=/opt/sonarqube
      - SONARQUBE_JDBC_USERNAME=sonar
      - SONARQUBE_JDBC_PASSWORD=sonar
      - SONARQUBE_JDBC_URL=jdbc:postgresql://db/sonar
# launch 
docker-compose up -d

You can then access your SonarQube instance on http://<ServerIP>:9000 with the credential admin/admin.