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https://github.com/philippechepy/exoscale-kubernetes-crio

Installation of Kubernetes with CRI-O on Exoscale platform through Packer and Terraform
https://github.com/philippechepy/exoscale-kubernetes-crio

cluster cluster-autoscaler cri-o exoscale hashicorp-packer hashicorp-terraform kubeadm kubernetes kubernetes-cluster packer terraform

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Installation of Kubernetes with CRI-O on Exoscale platform through Packer and Terraform

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# Autoscalable Kubernetes cluster at Exoscale, using Packer and Terraform



![Kubernetes](.documentation/images/kubernetes-logo.svg)



## TL;DR



The purpose of this repository is to install [Kubernetes](https://kubernetes.io) 1.20 with support for cluster autoscaling.

The cloud provider used is [Exoscale](https://www.exoscale.com). However this repository can be adapted to other providers.



The container runtime is [CRI-O](https://cri-o.io).

The network is managed by [Calico](https://www.projectcalico.org). It was chosen for its ease of installation (by default), and its polyvalence. Indeed, its performance is excellent in most use-cases compared to other alternatives, while keeping a reasonable resource consumption.



Two steps are involved in the installation of the cluster:



* The creation of a system image using [Packer](https://www.packer.io) and the Exoscale plugin. This image contains the packages for Kubernetes, [kubeadm](https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/) and CRI-O.

* The provisioning of the cluster using [Terraform](https://www.terraform.io) and the Exoscale provider (blazingly fast!)



## Explanations



This repository is explained in depth (in French) here :



* [Partie 1 : Préparation du dépôt](https://easyadmin.tech/tutoriel-comment-deployer-kubernetes-chez-exoscale-avec-packer-et-terraform-preparation-depot)

* [Partie 2 : Création d'une image de machine virtuelle](https://easyadmin.tech/tutoriel-comment-deployer-kubernetes-chez-exoscale-avec-packer-et-terraform-creation-image-machine-virtuelle)

* [Partie 3 : Création de l'infrastructure](https://easyadmin.tech/tutoriel-comment-deployer-kubernetes-chez-exoscale-avec-packer-et-terraform-creation-infrastructure)



## Installation



You must have docker installed locally in order to make the work done. Packer and Terraform are run using containers.



### First step: building the system image



```shell

# Download the Exoscale plugin for packer

make packer.deps



# Build and upload Kubernetes base system image in your Exoscale account's custom templates

# This step can take up to 10~15mn

make packer.build

```



### Update terraform variables



Next, you must create a `terraform/terraform.tfvars` file containing the template id you just built with packer (visible in the previous command output, or in the Exoscale interface).



```hcl

control_plane_template_id = "..."

node_template_id = "..."

```



### Build the final infrastructure



```shell

# Initialize terraform

make terraform.init



# Create the Kubernetes cluster

# This process usually takes 1 to 2 minutes to complete

make terraform.apply

```



## Connection to control-plane



```shell

# After provisioning your cluster

make ssh-cp

```



After connecting to the control-plane, you can play with kubectl.



# Infrastructure design



## Network



The communication between nodes is done via a managed private network (`exoscale_network` in Terraform).



All virtual machines are protected by a firewall which allows access to the necessary ports from the public network (`exoscale_security_group` and `exoscale_security_group_rules`). The default policy is to block all other connections (as in the Exoscale platform).



* The control-plane server allows inbound connections on port `22` (ssh) only.

* Workers allow incoming connections on ports `30000` to `32767` (TCP and UDP). Those ports match Kubernetes' NodePort range and allow the implementation of various `Services`.



* Outgoing connections are allowed from all virtual machines to the following ports:

TCP: `22` (SSH), `80` (HTTP), `443` (HTTPS), `11371` (HKP)

UDP: `53` (DNS)



## Virtual Machines



The Kubernetes cluster consists in a single virtual machine for the control-plane (`exoscale_compute` in Terraform). This machine hosts the Kubernetes API server along with Etcd.



Workers are implemented as an instance pool (`exoscale_instance_pool` in Terraform). This pool is configured to contain a single agent upon creation of the infrastructure. The autoscaler cluster will automatically increase the size of the instance pool as soon your workloads need it.



The control-plane server initializes its own services via a `kubeadm init` command.

New worker nodes (belonging to the instance pool) will automatically connect to the control-plane server in order to join the Kubernetes cluster (via `kubeadm`) on first boot.



The initialization of each virtual machine is controlled by cloud-init at the first instance startup.

See cloud-init [here for the control-plane](terraform/templates/control-plane/cloud-init.yaml), and [here for the workers](terraform/templates/nodes/cloud-init.yaml)



# Limitations



* Be careful when using this script in production (the cluster autoscaler has not been extensively tested in this configuration). **Use at your own risks!**



# References



* Kubernetes

  * [Website](https://kubernetes.io)

  * [Documentation](https://kubernetes.io/docs/home/)

* CRI-O

  * [Website](https://cri-o.io)

* Calico

  * [Website](https://www.projectcalico.org)

* Exoscale

  * [Website](https://www.exoscale.com)

  * [Documentation](https://community.exoscale.com)

  * [Cluster autoscaler](https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler/cloudprovider/exoscale)

* Packer

  * [Website](https://www.packer.io)

  * [Documentation](https://www.packer.io/docs)

  * [Creating Custom Templates Using Packer](https://www.exoscale.com/syslog/creating-custom-templates-using-packer/)

* Terraform

  * [Website](https://www.terraform.io)

  * [Documentation](https://www.terraform.io/docs/index.html)

  * [Exoscale Provider](https://registry.terraform.io/providers/exoscale/exoscale/latest/docs)



# Author



Philippe Chepy



* Github: [@PhilippeChepy](https://github.com/PhilippeChepy)

* LinkedIn: [@philippe-chepy](https://www.linkedin.com/in/philippe-chepy/)

* Website [EasyAdmin](https://easyadmin.tech)