Kubernetes

https://kubernetes.io/docs/reference/kubectl/cheatsheet/#kubectl-context-and-configuration

service kubelet stop
docker rm -f $(docker ps -a -q --filter "name=k8s")
service containerd stop

systemctl status kubelet
journalctl -xeu kubelet

Cluster Info

kubectl cluster-info
kubectl get nodes
kubectl get pods --all-namespaces -o wide
kubectl describe pod -n kubernetes-dashboard

SWAP OFF

Kubernetes does not run with swap enabled, because it may interfere. It must be disabled

swapoff /var/swapfile

SWAP ON

dd if=/dev/zero of=/var/swapfile bs=1M count=4128
mkswap /var/swapfile
chmod 777 /var/swapfile
echo "/var/swapfile none swap sw 0 0" >> /etc/fstab
swapon /var/swapfile

Rebuild Cluster

curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"

curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.30/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
sudo chmod 644 /etc/apt/keyrings/kubernetes-apt-keyring.gpg
echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.30/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo chmod 644 /etc/apt/sources.list.d/kubernetes.list

/etc/modules-load.d/modules.conf
overlay
br_netfilter

/etc/sysctl.d/ipv4_forward.conf
net.ipv4.ip_forward = 1

sudo apt install kubeadm kubelet containerd

/etc/containerd/config.toml
version = 2
root = "/var/lib/containerd"
state = "/run/containerd"
oom_score = 0
[plugins]
  [plugins."io.containerd.grpc.v1.cri"]
    [plugins."io.containerd.grpc.v1.cri".containerd]
      default_runtime_name = "runc"
      [plugins."io.containerd.grpc.v1.cri".containerd.runtimes]
      default_runtime_name = "runc"
      [plugins."io.containerd.grpc.v1.cri".containerd.runtimes]
        [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
          privileged_without_host_devices = false
          runtime_type = "io.containerd.runc.v2"
          [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
            BinaryName = "/usr/sbin/runc"
            SystemdCgroup = true

kubeadm reset
rm -rf /etc/cni/net.d
ip link delete cni0
ip link delete flannel.1

kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=10.0.0.203

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

kubeadm token create --print-join-command
kubeadm join 10.0.0.230:6443 --token 9uujzu.c1wjk2y65uiasfwf \
   --discovery-token-ca-cert-hash sha256:0ed142167d4edf1c96ec21522d2dda6b564cc139c03513a289016c357d5dc97b

kubectl get nodes
kubectl label node build node-role.kubernetes.io/worker=worker
kubectl describe node | grep -i taint
kubectl taint nodes build node-role.kubernetes.io/control-plane:NoSchedule-

kubectl get pods --all-namespaces -o wide
kubectl get events --namespace=kube-system
kubectl get endpoints  --namespace=kube-system
kubectl get endpoints  --namespace=kubernetes-dashboard

Flannel Network

kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml

DNS Troubleshoot

https://kubernetes.io/docs/tasks/administer-cluster/dns-debugging-resolution/

kubectl apply -f https://k8s.io/examples/admin/dns/dnsutils.yaml
kubectl get pods dnsutils
kubectl exec -i -t dnsutils -- nslookup kubernetes.default

Kubernetes Dashboard

helm upgrade --install kubernetes-dashboard kubernetes-dashboard/kubernetes-dashboard --create-namespace --namespace kubernetes-dashboard
helm repo add kubernetes-dashboard https://kubernetes.github.io/dashboard/

kubectl -n kubernetes-dashboard port-forward svc/kubernetes-dashboard-kong-proxy 8443:443

https://github.com/kubernetes/dashboard/blob/master/docs/user/access-control/creating-sample-user.md

kubectl apply -f serviceaccount.yaml
kubectl apply -f cluserbinding.yaml
kubectl -n kubernetes-dashboard create token admin-user

HAPROXY Ingress Helm

helm repo add haproxytech https://haproxytech.github.io/helm-charts helm repo update helm install haproxy haproxytech/kubernetes-ingress \

 --set controller.kind=DaemonSet --set controller.daemonset.useHostPort=true

HAPROXY Ingress Deployment

https://www.haproxy.com/blog/announcing-haproxy-kubernetes-ingress-controller-1-5/ https://www.haproxy.com/documentation/kubernetes/latest/configuration/controller/

kubectl apply -f https://raw.githubusercontent.com/haproxytech/kubernetes-ingress/master/deploy/haproxy-ingress.yaml

kubectl describe pod -n haproxy-controller haproxy-ingress-67f7c8b555-lw6cs kubectl describe pod -n haproxy-controller ingress-default-backend-78f5cc7d4c-2kvqv

NGINX

kubectl create namespace nginx
kubectl apply -f deployment-nginx.yaml -n nginx
kubectl create service nodeport nginx --tcp=80:80 -n nginx
kubectl apply -f nginx-ingress.yaml -n nginx

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:alpine
        ports:
        - containerPort: 80
EOF

spec:
  clusterIP: 10.105.252.237
  externalTrafficPolicy: Cluster
    greeting: hello
  ports:

ClusterIP: Exposes the Service on a cluster-internal IP. Choosing this value makes the Service only reachable from within the cluster. This is the default ServiceType. NodePort: Exposes the Service on each Node's IP at a static port (the NodePort). A ClusterIP Service, to which the NodePort Service routes, is automatically created. You'll be able to contact the NodePort Service, from outside the cluster, by requesting <NodeIP>:<NodePort>.

LoadBalancer: Exposes the Service externally using a cloud provider's load balancer. NodePort and ClusterIP Services, to which the external load balancer routes, are automatically created.

ExternalName: Maps the Service to the contents of the externalName field (e.g. foo.bar.example.com), by returning a CNAME record with its value. No proxying of any kind is set up.

Helm Mediawiki

helm repo add bitnami https://charts.bitnami.com/bitnami
helm install my-release bitnami/mediawiki
helm install 1.35.1 bitnami/mediawiki

redis
mediawiki
asterisk

Helm Bitnami

helm repo add bitnami https://charts.bitnami.com/bitnami helm install mediawiki bitnami/mediawiki

NAME: mediawiki
LAST DEPLOYED: Sun Feb  7 09:53:38 2021
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
###############################################################################
### ERROR: You did not provide an external host in your 'helm install' call ###
###############################################################################

This deployment will be incomplete until you configure Mediawiki with a resolvable
host. To configure Mediawiki with the URL of your service:

Get the Mediawiki URL by running:

kubectl get svc --namespace default -w mediawiki

export APP_HOST=$(kubectl get svc --namespace default mediawiki --template "Template:Range (index .status.loadBalancer.ingress 0){{ . }}Template:End")
export APP_PASSWORD=$(kubectl get secret --namespace default mediawiki -o jsonpath="{.data.mediawiki-password}" | base64 --decode)
export MARIADB_ROOT_PASSWORD=$(kubectl get secret --namespace default mediawiki-mariadb -o jsonpath="{.data.mariadb-root-password}" | base64 --decode)
export MARIADB_PASSWORD=$(kubectl get secret --namespace default mediawiki-mariadb -o jsonpath="{.data.mariadb-password}" | base64 --decode)

helm upgrade mediawiki bitnami/mediawiki \
   --set mediawikiHost=$APP_HOST,mediawikiPassword=$APP_PASSWORD,mariadb.auth.rootPassword=$MARIADB_ROOT_PASSWORD,mariadb.auth.password=$MARIADB_PASSWORD

kubectl get secret --namespace default mediawiki -o jsonpath="{.data.mediawiki-password}" | base64 --decode

OpenEBS

https://github.com/openebs/lvm-localpv/blob/develop/docs/storageclasses.md

helm repo add openebs https://openebs.github.io/openebs

helm repo update

helm install openebs --namespace openebs openebs/openebs --create-namespace

helm ls -n openebs

kubectl apply -f sc.yaml

kubectl get sc

Gluster

https://kubernetes.io/docs/concepts/storage/volumes/

https://github.com/kubernetes/examples/tree/master/volumes/glusterfs

https://github.com/gluster/glusterfs/issues/268

https://github.com/gluster/glusterfs/blob/master/libglusterfs/src/syncop.c

https://github.com/gluster/glusterfs/blob/master/doc/developer-guide/syncop.md

pthread context / getcontext, swapcontext, makecontext

SUSv2, POSIX.1-2001. POSIX.1-2008 removes the specifications of makecontext() and swapcontext(), citing portability issues, and recommending that applications be rewritten to use POSIX threads instead.

brickmux-thread-reduction.md

LVM Resize

lvreduce -L -24G /dev/vg-data/data
lvcreate -L 24G -n kubernetes vg-data
mkfs.xfs -i size=512 /dev/vg-data/kubernetes
mkdir -p /export/kubernetes/brick
echo "/dev/vg-data/kubernetes /export/kubernetes xfs defaults 0 0"  >> /etc/fstab
mount -a

gluster volume create gv0 ubuntu:/export/kubernetes/brick
gluster volume create gv0 replica 2 ubuntu:/export/kubernetes/brick u2:/export/kubernetes/brick
gluster volume info
gluster volume start gv0

mount -t glusterfs acer:gv0 /mnt/glusterfs

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Endpoints
metadata:
  name: glusterfs-cluster
subsets:
- addresses:
  - ip: 10.0.0.250
  ports:
  - port: 1
EOF

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - name: glusterfs
    image: nginx
    volumeMounts:
    - mountPath: "/usr/share/nginx/html/"
      name: glusterfsvol
  volumes:
  - name: glusterfsvol
    glusterfs:
      endpoints: glusterfs-cluster
      path: gv0
      readOnly: true
EOF

kubectl cp index.html nginx:/usr/share/nginx/html/

mount -t glusterfs acer:gv0 /mnt/glusterfs
cp ~/index.html .

apiVersion: v1
kind: PersistentVolume
metadata:
  name: gluster-pv
spec:
  capacity:
    storage: 24Gi
  storageClassName: standard
  accessModes:
  - ReadWriteMany    
  glusterfs:         
    endpoints: gluster-cluster 
    path: /gv0
    readOnly: false
  persistentVolumeReclaimPolicy: Retain

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: nginx-pvc
spec:
  accessModes:
    - ReadOnlyMany
  resources:
    requests:
      storage: 1Gi
  selector:
    matchLabels:
      name: standard

kind: PersistentVolume
apiVersion: v1
metadata:
  name: gluster-pv
  labels:
    name: models-1-0-0
spec:
  capacity:
    storage: 200Gi
  storageClassName: standard
  accessModes:
    - ReadOnlyMany
  gcePersistentDisk:
    pdName: models-1-0-0
    fsType: ext4
    readOnly: true
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: nginx-pvc
spec:
  accessModes:
    - ReadOnlyMany
  resources:
    requests:
      storage: 1Gi
  selector:
    matchLabels:
      name: glusterfs

lvreduce -L -24G /dev/vg-data/data
lvcreate -L 24G -n kubernetes vg-data
mkfs.xfs -i size=512 /dev/vg-data/kubernetes
mkdir -p /export/kubernetes/brick
echo "/dev/vg-data/kubernetes /export/kubernetes xfs defaults 0 0"  >> /etc/fstab
mount -a

sudo gluster volume info
gluster volume create gv0 ubuntu:/export/kubernetes/brick
gluster volume create gv0 replica 2 ubuntu:/export/kubernetes/brick u2:/export/kubernetes/brick
gluster volume info
gluster volume start gv0

mount -t glusterfs acer:gv0 /mnt/glusterfs
mount -t glusterfs ubuntu:gv0 /mnt/glusterfs
mount -t glusterfs ubuntu:gv1 /mnt/glusterfs
mount -t glusterfs ubuntu:gv2 /mnt/glusterfs

https://kubernetes.io/docs/concepts/storage/volumes/ https://github.com/kubernetes/examples/tree/master/volumes/glusterfs

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: PersistentVolume
metadata:
  name: gfs-pv0
spec:
  capacity:
    storage: 8Gi
  accessModes:
  - ReadWriteMany
  glusterfs:
    endpoints: gfs-cluster
    path: /gv0
    readOnly: false
  persistentVolumeReclaimPolicy: Retain
---
kind: PersistentVolume
apiVersion: v1
metadata:
  name: gfs-pv1
spec:
  capacity:
    storage: 8Gi
  accessModes:
  - ReadWriteMany
  glusterfs:
    endpoints: gfs-cluster
    path: /gv1
    readOnly: false
  persistentVolumeReclaimPolicy: Retain
---
kind: PersistentVolume
apiVersion: v1
metadata:
  name: gfs-pv2
spec:
  capacity:
    storage: 8Gi
  accessModes:
  - ReadWriteMany
  glusterfs:
    endpoints: gfs-cluster
    path: /gv2
    readOnly: false
  persistentVolumeReclaimPolicy: Retain
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: mariadb
spec:
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 8Gi
---
apiVersion: v1
kind: Endpoints
metadata:
  name: gfs-cluster
subsets:
- addresses:
  - ip: 10.0.0.230
  ports:
  - port: 1
---
apiVersion: v1
kind: Service
metadata:
  name: gfs-cluster
spec:
  ports:
  - port: 1
EOF

helm uninstall mariadb
helm install mariadb bitnami/mariadb --set primary.persistence.existingClaim=mariadb

kubectl get pods -w --namespace default -l release=mariadb
kubectl get secret --namespace default mariadb -o jsonpath="{.data.mariadb-root-password}" | base64 --decode
kubectl run mariadb-client --rm --tty -i --restart='Never' --image  docker.io/bitnami/mariadb:10.5.8-debian-10-r69 --namespace default --command -- bash

mysql -h mariadb.default.svc.cluster.local -uroot -p my_database

ROOT_PASSWORD=$(kubectl get secret --namespace default mariadb -o jsonpath="{.data.mariadb-root-password}" | base64 --decode)
helm upgrade mariadb bitnami/mariadb --set auth.rootPassword=$ROOT_PASSWORD

Azure EKS

Import-Module Az.Accounts
Connect-AzAccount
Install-AzAksKubectl
Write-Output $Env:Path
Import-AzAksCredential -ResourceGroupName cluster -Name cluster

kubectl version
kubectl config view --minify -o jsonpath='{.clusters[0].cluster.server}'
kubectl get nodes
kubectl get namespace
kubectl apply -f https://raw.githubusercontent.com/Azure-Samples/azure-voting-app-redis/master/azure-vote-all-in-one-redis.yaml
kubectl get pods
kubectl get services

kubectl cordon $(kubectl get nodes -o name)
kubectl.exe apply -f .\vote.yaml

https://azure.github.io/application-gateway-kubernetes-ingress/features/private-ip/ https://azure.github.io/application-gateway-kubernetes-ingress/

Remove-AzResourceGroup -Name cluster

kubectl apply -f https://raw.githubusercontent.com/Azure/application-gateway-kubernetes-ingress/master/deploy/azuredeploy.json

wget https://raw.githubusercontent.com/Azure/application-gateway-kubernetes-ingress/master/deploy/azuredeploy.json

resourceGroupName="cluster"
location="westeurope"
deploymentName="ingress-appgw"

Google GCP GKE

gcloud container clusters get-credentials your-first-cluster-1 --zone europe-north1-c --project third-light

gcloud compute ssh username@gke-your-first-cluster-1-pool-1-34a9d362
ssh -i id_ed25519 username@35.228.24.238
ssh -i .ssh/google_compute_engine username@35.228.239.240 -L 8444:10.3.255.31:8444
curl -vk https://localhost:8444

kube.config

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: LS0tLBVEUtLS0tLQo=
    server: https://35.228.120.76
  name: gke_third-light-233710_europe-north1-c_your-first-cluster-1
contexts:
- context:
    cluster: gke_third-light-233710_europe-north1-c_your-first-cluster-1
    user: gke_third-light-233710_europe-north1-c_your-first-cluster-1
    name: gke_third-light-233710_europe-north1-c_your-first-cluster-1
current-context: gke_third-light-233710_europe-north1-c_your-first-cluster-1
kind: Config
preferences: {}
users:
- name: gke_third-light-233710_europe-north1-c_your-first-cluster-1
  user:
    auth-provider:
      config:
        access-token: ya29.GlsjB2Z-Sk3dGWQVofpYCb7-06xo2ZLnpNJ7Ml67pkH
        cmd-args: config config-helper --format=json
        cmd-path: /usr/bin/gcloud
        expiry: "2019-06-09T09:39:47Z"
        expiry-key: '{.credential.token_expiry}'
        token-key: '{.credential.access_token}'
      name: gcp

Ignition

https://www.codetab.org/post/kubernetes-cluster-virtualbox/

storage:
  files:
    - path: /etc/sysctl.d/20-silence-audit.conf
      contents:
        inline: |
          kernel.printk=4
    - path: /etc/hostname
      mode: 420
      contents:
        source: "data:,fcos"

https://docs.okd.io/4.11/architecture/architecture-rhcos.html

sudo podman run --pull=always --privileged --rm \
   -v /dev:/dev -v /run/udev:/run/udev -v .:/data -w /data \
   quay.io/coreos/coreos-installer:release \
   install /dev/vdb -i config.ign

Alpine

https://wiki.alpinelinux.org/wiki/K8s

OpenEBS

kubectl apply -f https://openebs.github.io/charts/cstor-operator.yaml