uablrek

Most CNI-plugins doesn't support pod-pod multicast. A way to fix that is to add an ipvlan network using Multus. Howto install Multus and the whereabouts IPAM in you environemt is not in the scope of this gist.

Assuming multus and whereabouts are installed, create a "NAD" for ipvlan on the main K8s network.

uablrek

When trying https://github.com/LionelJouin/network-dra with crio instead of containerd it fails. The reason, or at least the first encountered problem, is that the OCI state differs:

Containerd:

{
  "ociVersion": "1.0.2-dev",
  "id": "f8a629809a08c9b1c45fae0fd34328dc29ece873cbe1ece14aaf35a2e370042b",
  "status": "creating",
  "pid": 1151,

uablrek

#! /bin/sh
##
## pod-ping.sh <src-pod> <dst-selector>
## Env:
##   SRC_NS - Source pod namespace
##   DST_NS - Destination pods namespace
## Example:
##   pod-ping.sh tserver-569b74646b-tnwzj app=tserver
##
if test -z "$2"; then

uablrek

k8s-coredump

Specify a core pattern on the host:

echo "/var/log/dumps/core.%h.%e.%P" > /proc/sys/kernel/core_pattern

This is global and will be seen inside containers.

Create a binary that causes a core-dump:

uablrek

Ipv4 address preservation in K8s KinD

In large cluster IPv4 addresses can become a limiting resource. In this gist we explore a way to assign IPv4 addresses to PODs on just some nodes using the MultiCIDRRangeAllocator feature. Project Calico may present other possibilities.

Configuration

uablrek

/*
  Provided under the MIT No Attribution License
  https://opensource.org/license/mit-0/

  Copyright 2023 Lars Ekman <emil71se@yahoo.com>

  Permission is hereby granted, free of charge, to any person
  obtaining a copy of this software and associated documentation files
  (the “Software”), to deal in the Software without restriction,
  including without limitation the rights to use, copy, modify, merge,

uablrek

package main

import (
	"fmt"
	"log"
	"net"
	"os"
	"strings"
)

uablrek

Kubernetes sig-network e2e tests

The list was produced by executing e2e tests with --ginkgo.dryRun=true and post-processing the result.

kubetest --provider=skeleton --test \
  --test_args="--ginkgo.focus=\[sig-network\] --ginkgo.dryRun=true --ginkgo.noColor=true" > \
  /tmp/sig-network-tests-raw.txt
grep -oE 'PASSED[^"]*' sig-network-tests-raw.txt | sort > /tmp/sig-network-tests.txt
sed -i -e 's,PASSED ,,' /tmp/sig-network-tests.txt

uablrek

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"os"

	core "k8s.io/api/core/v1"

uablrek

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <unistd.h>
#include <netdb.h>
#include <time.h>