K8S Study Environment

Requirements

1. Vagrant
2. Kubectl

Execute

Execute on the current folder:

vagrant up

After the process finish, a new file will be created on the local folder (kubernetes_config.conf). This file is the k8s config file.

Use the KUBECONFIG environment variable to use this k8s instance.

export KUBECONFIG="$(pwd)/kubernetes_config.conf"

To test:

$ kubectl get nodes
NAME               STATUS   ROLES           AGE     VERSION
k8s-controlplane   Ready    control-plane   80m     v1.26.1
k8s-worker-1       Ready    <none>          9m31s   v1.26.1
k8s-worker-2       Ready    <none>          3m56s   v1.26.1

Delete the env

vagrant destroy

Use suspend/resume to pause de execution

vagrant suspend
vagrant resume

Enable MetalLB

Based on MetalLB doc

Enable strictARP

kubectl get configmap kube-proxy -n kube-system -o yaml | \
sed -e "s/strictARP: false/strictARP: true/" | \
kubectl apply -f - -n kube-system

Install MetalLB

kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.13.9/config/manifests/metallb-native.yaml

Configure MetalLB

1. Create a YAML file (metallb-conf.yaml)

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: metallb-addr-pool
  namespace: metallb-system
spec:
  addresses:
  - 192.168.121.100-192.168.121.199

---
apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: metallb-l2advertisement
  namespace: metallb-system

2. Apply the config file

kubectl apply -f metallb-conf.yaml

Remove all vagrant instances

This command stops the running machine Vagrant is managing and destroys all resources that were created during the machine creation process.

vagrant destroy

Run Ansible on remote servers

To run the ansible playbook on remote servers, first create a inventory file inside kubernetes-setup directory

[all:vars]
ansible_user=root

[controlplane]
192.168.165.10

[workers]
192.168.165.11
192.168.165.12

[storage]
192.168.165.15

Run ansible main playbook

ansible-playbook -i inventory k8s-cluster.yml

Enable K8S Metrics Server

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

If the metrics server doesn't work correctly, perform the following configuration changes

Fonte: https://www.devopszones.com/2022/06/kubernetes-error-from-server.html

kubectl patch deployments -n kube-system metrics-server \
   --type=json -p '{"spec": {"template": {"spec": {"hostNetwork": true, "dnsPolicy": "ClusterFirst"}}}}'

# Only when using invalid certificates.. (x509: cannot validate certificate)
kubectl patch deployments.apps -n kube-system metrics-server \
   --type=json -p '[{"op": "add", "path": "/spec/template/spec/containers/0/args/-", "value": "--kubelet-insecure-tls" }]'