Archana Shinde amshinde

Getting docker to work with corporate proxy

Docker's conf file /etc/docker/daemon.json :

{  
   "dns":[  
      "10.248.2.1",
      "10.22.224.196"
   ],
 "dns-search":[

Resources for guest time sync:

Beta support for raw block volumes is available in K8s 1.13: https://kubernetes.io/blog/2019/03/07/raw-block-volume-support-to-beta/

The following in-tree volumes types support raw blocks:

AWS EBS
Azure Disk
Cinder

curl -O https://storage.googleapis.com/golang/go1.22.4.linux-amd64.tar.gz
sudo rm -rf /usr/local/go && sudo tar -C /usr/local -xzf go1.22.4.linux-amd64.tar.gz
sudo ln -sf /usr/local/go/bin/go /usr/bin/go

vim ~/.bashrc
export GOPATH=$HOME/go
export PATH=$PATH:/usr/local/go/bin:$GOPATH/bin

vim /etc/profile

#side by side terminal diff
git difftool -y -x "sdiff -w $COLUMNS" | less

Setting up a overlay network using point to multi-point GRE tunnels

Multi-Point GRE Tunnels

Typically VxLAN is used to setup a point to multi-point overlay networks. However GRE also offers a similar capability which is often not heavily used. This document calls out how to setup an effient overlay mesh network to link up multiples sits together using multi point GRE tunnels.

Setup

The setup used in this case assumes there is a need to link three sites hosting three different subnets together using a simple overlay mesh network.

The netfilter hooks in the kernel and where they hook in the packet flow

The figure below calls out

The netfilter hooks
The order of table traversal

Failed to add inotify watch : no space left on disk

This is due to the inotify watch limit being hit. cat /proc/sys/fs/inotify/max_user_watches

sudo sysctl fs.inotify.max_user_watches=524288

or edit

How to use VFIO to assign a device to nested VM

Here the vfio-pci device is passed in into the L1 VM
The L1 VM is setup with kernel_irqchip=split
The L0 exposes a virtual IOMMU to the L1 VM

qemu-system-x86_64 \
    -machine q35,accel=kvm,kernel_irqchip=split \
    -enable-kvm \

	sudo -E qemu-lite-system-x86_64 -machine pc,accel=kvm,kernel_irqchip -cpu host -m 2G,slots=3,maxmem=16G -object memory-backend-file,id=mem,size=2G,mem-path=/dev/shm,share=on -numa node,memdev=mem -device virtio-serial-pci,id=serial0 -device virtio-blk-pci,drive=image -drive if=none,id=image,file=kata-containers.img,format=raw -kernel vmlinuz.container -append 'console=ttyS0 console=hvc0 iommu=false root=/dev/vda1 rw rootfstype=ext4 data=ordered rcupdate.rcu_expedited=1 tsc=reliable no_timer_check loglevel=7 apic=verbose noapic noapictimer virtio_mmio.device=0x200@0x540000000:14' -smp 2,maxcpus=4 -device virtconsole,chardev=charconsole0,id=console0 -chardev stdio,id=charconsole0 -monitor telnet:127.0.0.1:55555,server,nowait -device isa-debugcon,iobase=0x402,chardev=debugcon -chardev file,path=/tmp/debug-log,id=debugcon -device isa-debugcon,iobase=0x3f8,chardev=serialcon -chardev file,path=/tmp/serial-log,id=serialcon
	[sudo] password for amshinde:
	[ 0.223920] brd: module loaded
	[ 0.226454]