POC environments

Single master Kubernetes clusters (POC). One with embedded etcd, the other one with external etcd as a PostgreSQL database.

Note: Run once at a time. Place a .deact suffix to external.tf or embeded.tf file.

Demo APP: Guestbook

$ kubectl apply -f https://k8s.io/examples/application/guestbook/redis-master-deployment.yaml
$ kubectl apply -f https://k8s.io/examples/application/guestbook/redis-master-service.yaml
$ kubectl apply -f https://k8s.io/examples/application/guestbook/redis-slave-deployment.yaml
$ kubectl apply -f https://k8s.io/examples/application/guestbook/redis-slave-service.yaml
$ kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-deployment.yaml
$ kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-service.yaml
$ kubectl scale deployment frontend --replicas=5

Backup & Restore: external DB Cluster

Step By Step

# Get the instance certificate:
$ terraform output external_tls_private_key > cluster.key && chmod 600 cluster.key
# Enter the instance
$ ssh -i cluster.key external@$(terraform output external_master_public_ip)
# Wait for Kubectl to be running. Check number of nodes. Then run a sample nginx
master$ kubectl run nginx --image nginx:latest --port 80 --expose --replicas=3
master$ kubectl expose deployment nginx --type NodePort --target-port 80 --name nginx-external
# Backup PKI
master$ sudo tar -zcvf /tmp/pki.tar.gz /etc/kubernetes/pki
# Download Backup
$ scp -i cluster.key external@$(terraform output external_master_public_ip):/tmp/pki.tar.gz pki.tar.gz
pki.tar.gz

Destroy master via AWS Console

$ terraform plan
$ terraform apply --auto-approve
$ scp -i cluster.key pki.tar.gz external@$(terraform output external_master_public_ip):/tmp/pki.tar.gz
$ ssh -i cluster.key external@$(terraform output external_master_public_ip)
master$ tar -zxvf /tmp/pki.tar.gz
master$ sudo kubeadm reset -f
restore pki
master$ sudo mv etc/kubernetes/pki/ /etc/kubernetes/
master$ sudo kubeadm init --config /etc/kubernetes/kubeadm.config.yaml --ignore-preflight-errors=ExternalEtcdVersion --node-name=$(hostname -f)

Enjoy

Backup & Restore: embedded DB Cluster

Step By Step

• Create the cluster: terraform apply --auto-approve (remove, if any, the master_backup_ami value)
  • Enter the master node: terraform output embeded_tls_private_key > key && chmod 600 key && ssh -i key embeded@$(terraform output embeded_master_public_ip)
  • Wait for every node to join the cluster. Run watch kubectl get nodes in the master node.
• Scale CoreDNS: kubectl scale deploy coredns -n kube-system --replicas=5
• Deploy guestbook application (see commands above)
  • test it (Get the public IP of a worker instance from the AWS Console, get the port number of the frontend service)
    • http://IP:SVC-NODEPORT
    • http://IP:SVC-NODEPORT/guestbook.php?cmd=get&key=messages
• Create an AMI snapshot (Don't forget to mark to don't restart the instance while snapshotting)
  • Wait for the completion
• Deploy a pod (alter the etcd state somehow)
• Destroy the master instance
  • ATTENTION: During the destroy, some errors could happen
  • Check everything continues working
    • http://IP:SVC-NODEPORT
    • http://IP:SVC-NODEPORT/guestbook.php?cmd=get&key=messages
• terraform apply (with the master_backup_ami value)
• Check everything continues working
  • Wait for everything working
    • http://IP:SVC-NODEPORT
    • http://IP:SVC-NODEPORT/guestbook.php?cmd=get&key=messages
• Restart worker kubelets
• $ ssh -i key [email protected] sudo systemctl restart kubelet
• kubectl rollout restart ds kube-proxy -n kube-system
• kubectl run nginx --image nginx:latest

Enjoy