tf-kubeadm-otc

Install Kubeadm OTC with Tofu

Pre-requirements

• install tofu
• have a OTC tenant and AK/SK credentials

Deployment

• Create a terraform.tfvars file in the main folder

mandatory flags:

# app
environment    = <environment name>  # e.g. "kubeadm-test"
kubeadm_host   = <hostname>          # e.g. "kubeadm"
kubeadm_domain = <fqdn>              # e.g. "example.com"
create_dns     = "true"
flavor_id      = "c3.xlarge.2"
# secret
access_key     = <otc access key>
secret_key     = <otc secret key>
domain_name    = <otc user domain>"
public_key     = <public ssh key vor ECS>

additional features (optional):

create_dns     = <create dns zone/zonerecord in otc for rancher_host/rancher_dom> # e.g. "true"
admin_email    = <admin email address for DNS/LetsEncrypt> # e.g. "[email protected]"

tofu init
tofu plan
tofu apply -auto-approve

kubeadm installation

There are various steps to prepare Kubernetes installation done by cloud-init

• set kernel parameters
• set container engine
• install kubeadm, kubelet, kubectl
• create the cluster (single node)
• untain the control-node and make this as worker
• install tooling like helm
• install local-storage provisioner
• generate kube config credential file to download via ssh

Output

After tofu apply or tofu output show a lot of information to access the cluster:

Outputs:

kubeadm-api = "https://kubeadm.otc.mcsps.de"
kubeadm-info = [
  "Welcome to Kubeadm at OTC! It will take up to 5 minutes before your cluster is ready and accessable",
  "To get kubeadm config from lighttpd server:",
  "curl -o kubeadm.config http://164.30.35.56:8085/cvivcfat6mol7te0e4jxr5zez0m0ig53/kubeadm.config",
  "export KUBECONFIG=$(pwd)/kubeadm.config",
  "To get kubeadm config via scp:",
  "scp [email protected]:/var/www/html/cvivcfat6mol7te0e4jxr5zez0m0ig53/kubeadm.config .;export KUBECONFIG=./kubeadm.config",
  "To access the server via ssh:",
  "ssh [email protected]",
  "We provided some additional resource via install script on /install-software.sh",
  "To get: curl -o install-software.sh http://164.30.35.56:8085/cvivcfat6mol7te0e4jxr5zez0m0ig53/install-software.sh",
]

$ scp [email protected]:/var/www/html/cvivcfat6mol7te0e4jxr5zez0m0ig53/kubeadm.config .;export KUBECONFIG=./kubeadm.config
$ kubectl get nodes
NAME                   STATUS   ROLES           AGE     VERSION
kubeadm-test-kubeadm   Ready    control-plane   6m19s   v1.28.15

Software

Within cloud-init a file named /install-software.sh will installed. It can be executed to install

• kube-prometheus-stack
• kube-logging
• ingress-nginx
• kube-vip

see hints in the file for further information

Shutdown-Mode

Since Version 1.23.6 Terraform Open Telekom Cloud can handle ECS instance power state.

Shutoff:

tofu apply -auto-approve --var power_state=shutoff

Active:

tofu apply -auto-approve --var power_state=active

Retirement:

tofu destroy

Credits:

Frank Kloeker [email protected]

Life is for sharing. If you have an issue with the code or want to improve it, feel free to open an issue or an pull request.