Gilang Virga Perdana gilangvperdana

Change default DNS nameserver used by Kubernetes pods

This can be applied generically but usually applies to Linux nodes that have a local caching nameserver running, which means pointing to an IP in the loopback range (127.0.0.0/8). Ubuntu 18.04 Bionic Beaver does this by default.

Option 1: Change host configuration

sudo systemctl mask systemd-resolved
rm -f /etc/resolv.conf
sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf

IP Tables (iptables) Cheat Sheet

IPTables is the Firewall service that is available in a lot of different Linux Distributions. While modifiying it might seem daunting at first, this Cheat Sheet should be able to show you just how easy it is to use and how quickly you can be on your way mucking around with your firewall.

Resources

The following list is a great set of documentation for iptables. I used them to compile this documentation.

How-To Geek: The Beginner’s Guide to iptables, the Linux Firewall: https://www.howtogeek.com/177621/the-beginners-guide-to-iptables-the-linux-firewall/
IPTables Essentials: Common Firewall Rules and COmmands https://www.digitalocean.com/community/tutorials/iptables-essentials-common-firewall-rules-and-commands

Virt-Manager Installation (for ubuntu based distrib)

This gist will give you all installation steps needed to install properly virt-manager with all dependencies.

Dependencies

Here is the list of all dependencies required to install properly virt-manager on your ubuntu based distrib.

libvirt-bin
qemu

How to setup Let's Encrypt for Nginx on Ubuntu 18.04 (including IPv6, HTTP/2 and A+ SLL rating)

Virtual hosts

Let's say you want to host domains first.com and second.com.

Create folders for their files:

	# Source: https://stackoverflow.com/a/43317244
	$path = ".\aws-ec2-key.pem"
	# Reset to remove explict permissions
	icacls.exe $path /reset
	# Give current user explicit read-permission
	icacls.exe $path /GRANT:R "$($env:USERNAME):(R)"
	# Disable inheritance and remove inherited permissions
	icacls.exe $path /inheritance:r

	Some notes from engineering.

	1) Identify the partition

	Mnesia('rabbit@juju-machine-30-lxd-11'): ERROR mnesia_event got {inconsistent_database, running_partitioned_network, 'rabbit@juju-machine-29-lxd-9'}

	$ sudo rabbitmqctl cluster_status

	2) Pick the most reliable node as the master.

	#!/usr/bin/env bash

	# set -x

	if [[ $EUID -ne 0 ]]; then
	echo "You must be root to run this script"
	exit 1
	fi

	# Returns all available interfaces, except "lo" and "veth*".


	user nginx;

	# one(1) worker or equal the number of _real_ cpu cores. 4=4 core cpu
	worker_processes 4;

	# renice workers to reduce priority compared to system processes for
	# machine health. worst case nginx will get ~25% system resources at nice=15
	worker_priority -5;

	# The full public facing url
	#root_url = %(protocol)s://%(domain)s:%(http_port)s/
	root_url = http://localhost:80/grafana/

	qemu-img convert -O vdi gnome.qcow2 gnome.vdi


	#if its a raw image then:
	VBoxManage convertdd opnstk.raw VBox.vdi --format VDI