Outline

• what's kind?
• other choices
• inside kind
  • docker in docker
  • LoadBalancers -
    cloud-provider-kind

Deep Dive: Kind

Nov 22, 2019

Deep Dive: Kind

• test kubernetes
• E2E testing
• 7:30 Networking Deep Dive (kindnet)

Testing your K8s apps with KIND

May 24, 2019

Quick start

https://kind.sigs.k8s.io/docs/user/quick-start/

# fetch release binary
curl -Lo ~/bin/kind https://kind.sigs.k8s.io/dl/v0.26.0/kind-linux-amd64 && chmod +x ~/bin/kind

$ kind create cluster

$ kind get clusters
kind

$ kubectl get nodes -o wide
NAME                 STATUS   ROLES           AGE   VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE                         KERNEL-VERSION                                        CONTAINER-RUNTIME
kind-control-plane   Ready    control-plane   52s   v1.32.0   10.89.0.2     <none>        Debian GNU/Linux 12 (bookworm)   6.13.0-0.rc1.20241206gitb8f52214c61a.19.fc42.x86_64   containerd://1.7.24

What is a kubernetes

What is a kind cluster? - kind nodes

$ podman ps

CONTAINER ID  IMAGE                                                                                           COMMAND     CREATED        STATUS        PORTS                      NAMES
13b1bfcafa48  docker.io/kindest/node@sha256:c48c62eac5da28cdadcf560d1d8616cfa6783b58f0d94cf63ad1bf49600cb027              3 minutes ago  Up 3 minutes  127.0.0.1:37513->6443/tcp  kind-control-plane

$  podman exec -it kind-control-plane bash
root@kind-control-plane:/# systemctl status kubelet.slice
● kubelet.slice - slice used to run Kubernetes / Kubelet
     Loaded: loaded (/etc/systemd/system/kubelet.slice; static)
     Active: active since Wed 2024-12-25 14:25:51 UTC; 5min ago
      Tasks: 174
     Memory: 460.4M
        CPU: 26.736s
     CGroup: /kubelet.slice
             ├─kubelet-kubepods.slice
...

containers in kind node

ctr  -n k8s.io c ls
CONTAINER                                                           IMAGE                                                          RUNTIME
0cc5dbdf2b34ff037bae5693ee6e64d3c9cb9f8ae32ab153d0e6cdc8a12eebd2    registry.k8s.io/pause:3.10                                     io.containerd.runc.v2
2584e9ca5a3c9725b76539ee7e736adee1c287ccd8d55031f5afdf9fa6c3390d    registry.k8s.io/kube-apiserver-amd64:v1.32.0                   io.containerd.runc.v2
37104ddf07cf3ce0bc8b56659d7a17304f017b6d4ce652301a91e5324b9cf82a    registry.k8s.io/kube-proxy-amd64:v1.32.0                       io.containerd.runc.v2
3f8dfdd4eac682e21a082eb89f6ff98f37cf666e1cc93be7b1bbdfd3b0dff320    registry.k8s.io/kube-scheduler-amd64:v1.32.0                   io.containerd.runc.v2

...

tips:

kubie

A more powerful alternative to kubectx and kubens
https://github.com/sbstp/kubie

• Shell prompt modification
• Split configuration files
• kubie exec

known-issues

• https://kind.sigs.k8s.io/docs/user/known-issues/
• like max_user_instances

privileged mode

https://learn.snyk.io/lesson/container-runs-in-privileged-mode/

systemd in Docker

from debian:11
run apt -y update
run apt -y install systemd

# first tell systemd that it is in docker (it will check for the container env)
# https://systemd.io/CONTAINER_INTERFACE/
ENV container=docker

# systemd exits on SIGRTMIN+3, not SIGTERM (which re-executes it)
# https://bugzilla.redhat.com/show_bug.cgi?id=1201657
STOPSIGNAL SIGRTMIN+3
# NOTE: this is *only* for documentation, the entrypoint is overridden later
RUN passwd -d root
ENTRYPOINT [ "/lib/systemd/systemd" ]

more deeper

• kubelet - https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet/
• kubeadm -
• kubelet plugin
• nvkind - https://github.com/NVIDIA/nvkind/
• cri-o in kind

kubeadm

https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/

cri-o in kind
https://github.com/cri-o/cri-o/blob/main/tutorials/crio-in-kind.md

cloud-provider-kind - one service one kindccm

podman ps

a0a8b3c02bab  docker.io/envoyproxy/envoy:v1.30.1                                                              bash -c echo -en ...  About an hour ago  Up About an hour  0.0.0.0:40617->10000/tcp   kindccm-KDNZI53UFUSNY4WSWHFWVBBUZDBQ3EQ5KR66Y5RJ

• kubectl port-forward service/doc-controller 8080：8080

https://kccnceu2024.sched.com/event/1YhhY/keep-calm-and-load-balance-on-kind-antonio-ojea-benjamin-elder-google

Other tips

• Local Registry
• kubie

nvkind

• https://github.com/NVIDIA/nvkind/

• https://github.com/NVIDIA/k8s-device-plugin/

• https://www.youtube.com/watch?v=jnHlwZKJiL4

• docker only