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k8s-flannel-incluster.md

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Quick Start Guide with K8s and LoxiLB in-cluster mode

This guide will explain how to:

  • Deploy a single-node K8s cluster with flannel networking
  • Run loxilb in-cluster mode
  • Expose services with loxilb as an external load balancer

Pre-requisite

  • Single node with Linux (kernel version >=5.15) for running Kubernetes
  • Bastion or Host node to consume the services running in same network subnet as K8s node

Topology

For quickly bringing up loxilb with K8s, we will be deploying all components in a single node :

image

All components of loxilb run as part of the K8s cluster in this scenario. loxilb can be used with various HA options as well, but skipped here for simplicity.

Setup K8s node

We will setup the single node Kubernetes setup using kubeadm.

Prepare the node

# disable swap
sudo swapoff -a

# keeps the swap off during reboot
(crontab -l 2>/dev/null; echo "@reboot /sbin/swapoff -a") | crontab - || true
sudo apt-get update -y

# Kernel Forwarding 
cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
br_netfilter
EOF

# Set up required sysctl params, these persist across reboots.
cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

sudo sysctl --system

# Install docker to be used as container-runtime by Kubernetes
sudo apt install -y docker.io
sudo usermod -aG docker vagrant

Install docker container runtime (or any runtime as per user preference)

# cri-docker Install
VER=$(curl -s https://api.github.com/repos/Mirantis/cri-dockerd/releases/latest|grep tag_name | cut -d '"' -f 4|sed 's/v//g')
echo $VER
wget -q https://github.com/Mirantis/cri-dockerd/releases/download/v${VER}/cri-dockerd-${VER}.amd64.tgz --retry-connrefused  --waitretry=1 --read-timeout=20 --timeout=15 --tries=5 --continue
tar xvf cri-dockerd-${VER}.amd64.tgz
sudo mv cri-dockerd/cri-dockerd /usr/local/bin/

wget -q https://raw.githubusercontent.com/Mirantis/cri-dockerd/master/packaging/systemd/cri-docker.service --retry-connrefused  --waitretry=1 --read-timeout=20 --timeout=15 --tries=5 --continue
wget -q https://raw.githubusercontent.com/Mirantis/cri-dockerd/master/packaging/systemd/cri-docker.socket --retry-connrefused  --waitretry=1 --read-timeout=20 --timeout=15 --tries=5 --continue
sudo mv cri-docker.socket cri-docker.service /etc/systemd/system/
sudo sed -i -e 's,/usr/bin/cri-dockerd,/usr/local/bin/cri-dockerd,' /etc/systemd/system/cri-docker.service

sudo systemctl daemon-reload
sudo systemctl enable cri-docker.service
sudo systemctl enable --now cri-docker.socket

# cri-docker Active Check
sudo systemctl restart docker && sudo systemctl restart cri-docker
sudo systemctl status cri-docker.socket --no-pager

# Docker cgroup Change Require to Systemd
sudo mkdir -p /etc/docker || true
cat <<EOF | sudo tee /etc/docker/daemon.json
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF

sudo systemctl restart docker && sudo systemctl restart cri-docker

Install Kubernetes dependencies

sudo apt-get install -y apt-transport-https ca-certificates curl gpg
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.29.2/deb/Release.key | sudo gpg --no-tty --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.29.2/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list

sudo apt-get update -y
sudo apt-get install -y kubelet kubectl kubeadm
sudo apt-get update -y
sudo apt-get install -y jq
sudo apt-get install -y ipvsadm

Install Kubernetes with kubeadm

First create a kubeadm-config.yaml with following contents :

(Note that 192.168.80.250 is the nodeIP of the Kubernetes node)

apiVersion: kubeadm.k8s.io/v1beta3
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 192.168.80.250
  bindPort: 6443
nodeRegistration:
  imagePullPolicy: IfNotPresent
  name: master
  taints: null
  kubeletExtraArgs:
    node-ip: 192.168.80.250
  criSocket: unix:///var/run/cri-dockerd.sock
---
apiVersion: kubeadm.k8s.io/v1beta3
certificatesDir: /etc/kubernetes/pki
kind: ClusterConfiguration
apiServer:
  timeoutForControlPlane: 4m0s
  certSANs:
  - 192.168.80.250
controlPlaneEndpoint: 192.168.80.250:6443
clusterName: kubernetes
controllerManager: {}
dns: {}
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: registry.k8s.io
kubernetesVersion: v1.29.2
networking:
  dnsDomain: cluster.local
  podSubnet: 10.244.0.0/16
  serviceSubnet: 10.245.0.0/18
scheduler: {}
--
apiVersion: kubeproxy.config.k8s.io/v1alpha1
bindAddress: 0.0.0.0
clientConnection:
  acceptContentTypes: ""
  burst: 10
  contentType: application/vnd.kubernetes.protobuf
  kubeconfig: /var/lib/kube-proxy/kubeconfig.conf
  qps: 5
clusterCIDR: ""
configSyncPeriod: 15m0s
#featureGates: "SupportIPVSProxyMode=true"
enableProfiling: false
healthzBindAddress: 0.0.0.0:10256
hostnameOverride: ""
iptables:
  masqueradeAll: false
  masqueradeBit: 14
  minSyncPeriod: 0s
  syncPeriod: 30s
ipvs:
  excludeCIDRs: null
  minSyncPeriod: 0s
  scheduler: ""
  syncPeriod: 30s
kind: KubeProxyConfiguration
metricsBindAddress: 127.0.0.1:10249
nodePortAddresses: null
oomScoreAdj: -999
portRange: ""
---
kind: KubeletConfiguration
apiVersion: kubelet.config.k8s.io/v1beta1
cgroupDriver: systemd

Run kubeadm to complete installation:

sudo kubeadm init --ignore-preflight-errors Swap --config kubeadm-config.yaml

Setup kubeconfig for running kubectl conveniently (optional)

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

Label the node and remove taints to make sure pods are scheduled properly (since it is a single node setup)

kubectl label node $(hostname -s) node-role.kubernetes.io/worker=''
kubectl label node $(hostname -s) node.kubernetes.io/exclude-from-external-load-balancers-
kubectl taint nodes --all node-role.kubernetes.io/control-plane-

Deploying loxilb in K8s

Use the following command :

kubectl apply -f https://raw.githubusercontent.com/loxilb-io/kube-loxilb/refs/heads/main/manifest/in-cluster/loxilb-nobgp.yaml

Deploying kube-loxilb in K8s

kube-loxilb is used to deploy loxilb with Kubernetes.

wget https://raw.githubusercontent.com/loxilb-io/kube-loxilb/refs/heads/main/manifest/in-cluster/kube-loxilb.yaml

Change the contents of kube-loxilb.yaml "args" to the following (leaving others commented) :

        args:
          #- --loxiURL=http://192.168.80.10:11111
          - --cidrPools=defaultPool=192.168.80.100/32
          - --setRoles=0.0.0.0
          #- --setBGP=64512
          #- --listenBGPPort=1791
          #- --monitor
          #- --extBGPPeers=50.50.50.1:65101,51.51.51.1:65102
          #- --setLBMode=1

The CIDR is set to any unused IP/subnet in the local network.

Apply the yaml contents :

kubectl apply -f kube-loxilb.yaml

Spawn a test pod and create a LB service

cat << EOF | kubectl apply -f -
apiVersion: v1
kind: Service
metadata:
  name: tcp-lb-onearm
  annotations:
    loxilb.io/liveness: "yes"
    loxilb.io/lbmode: "onearm"
spec:
  externalTrafficPolicy: Local
  loadBalancerClass: loxilb.io/loxilb
  selector:
    what: tcp-onearm-test
  ports:
    - port: 55002
      targetPort: 80 
  type: LoadBalancer
---
apiVersion: v1
kind: Pod
metadata:
  name: tcp-onearm-test
  labels:
    what: tcp-onearm-test
spec:
  containers:
    - name: tcp-onearm-test
      image: ghcr.io/loxilb-io/nginx:stable
      ports:
        - containerPort: 80
EOF

For detailed explanation of various annotations, please check this guide.

Check the status

Check Kubernetes services status :

kubectl get svc
NAME            TYPE           CLUSTER-IP    EXTERNAL-IP          PORT(S)           AGE
kubernetes      ClusterIP      10.245.0.1    <none>               443/TCP           31m
tcp-lb-onearm   LoadBalancer   10.245.2.83   llb-192.168.80.100   55002:32057/TCP   45s

Check create LB rules in loxilb pod :

$ kubectl get pods -A |grep loxilb-lb
kube-system    loxilb-lb-sws2g                  1/1     Running   0          4m14s

$ kubectl exec -it -n kube-system loxilb-lb-sws2g  -- loxicmd get lb -o wide
|     EXT IP     | SEC IPS | HOST | PORT  | PROTO |         NAME          | MARK | SEL |  MODE  |    ENDPOINT    | EPORT | WEIGHT | STATE  | COUNTERS |
|----------------|---------|------|-------|-------|-----------------------|------|-----|--------|----------------|-------|--------|--------|----------|
| 192.168.80.100 |         |      | 55002 | tcp   | default_tcp-lb-onearm |    0 | rr  | onearm | 192.168.80.250 | 31640 |      1 | active | 11:818   |

Connect from host/client

$ curl http://192.168.80.100:55002
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>