Quick Start Instructions

This are the instructions to quickly deploy Kuberentes Pi-cluster using the following tools:

cloud-init: to automate initial OS installation/configuration on each node of the cluster
Ansible: to automatically configure cluster nodes, install and configure external services (DNS, DHCP, Firewall, S3 Storage server, Hashicorp Vautl) install K3S, and bootstraping cluster through installation and configuration of ArgoCD
Argo CD: to automatically deploy Applications to Kuberenetes cluster from manifest files in Git repository.

Note:

Step-by-step manual process to deploy and configure each component is also described in this documentation.

Ansible control node setup

Use your own Linux-based PC or set-up a Ubuntu Server VM to become ansible control node (pimaster)

In case of building a VM check out tip for automating its creation in “Ansible Control Node”.
Clone Pi-Cluster Git repo or download using the ‘Download ZIP’ link on GitHub.
```
git clone https://github.com/ricsanfre/pi-cluster.git
```
Install docker and docker-compose

Follow instructions in “Ansible Control Node: Installing Ansible Runtime environment”.
Create and configure Ansible execution environment (ansible-runner):
```
make ansible-runner-setup
```
This will automatically build and start ansible-runner docker container (including all packages and its dependencies), generate GPG key for encrypting with ansible-vault and create SSH key for remote connections.

Ansible configuration

Ansible configuration (variables and inventory files) might need to be adapted to your particular environment

Inventory file

Adjust ansible/inventory.yml inventory file to meet your cluster configuration: IPs, hostnames, number of nodes, etc.

Tip:

If you maintain the private network assigned to the cluster (10.0.0.0/24) and nodes’ hostname and IP address, mac field (node’s mac address) is the only that you need to change in inventory.yml file. MAC addresses are used by DHCP server to assign the proper IP to each node.

MAC addresses can be obtained when Raspberry PI is booted for first time during the firmware update step: see Raspberry PI Firmware Update.

Configuring ansible remote access

The UNIX user to be used in remote connections (i.e.: ricsanfre) and its SSH key file location need to be specified.

Modify ansible/group_vars/all.yml to set the UNIX user to be used by Ansible in the remote connection, ansible_user (default value ansible) and its SSH private key, ansible_ssh_private_key_file

  # Remote user name
  ansible_user: ricsanfre

  # Ansible ssh private key
  ansible_ssh_private_key_file: ~/.ssh/id_rsa

By default it uses the ssh key automatically created when initializing ansible-runner (make ansible-runner-setup) located at ansible-runner/runner/.ssh directory.

Modify Ansible Playbook variables

Adjust ansible playbooks/roles variables defined within group_vars, host_vars and vars directories to meet your specific configuration.

The following table shows the variable files defined at ansible’s group and host levels

Group/Host Variable file	Nodes affected
ansible/group_vars/all.yml	all nodes of cluster + gateway node + pimaster
ansible/group_vars/control.yml	control group: gateway node + pimaster
ansible/group_vars/k3s_cluster.yml	all nodes of the k3s cluster
ansible/group_vars/k3s_master.yml	K3s master nodes
ansible/host_vars/gateway.yml	gateway node specific variables

The following table shows the variable files used for configuring the storage, backup server and K3S cluster and services.

Specific Variable File	Configuration
ansible/vars/picluster.yml	K3S cluster and external services configuration variables
ansible/vars/centralized_san/centralized_san_target.yml	Configuration iSCSI target local storage and LUNs: Centralized SAN setup
ansible/vars/centralized_san/centralized_san_initiator.yml	Configuration iSCSI Initiator: Centralized SAN setup

Important: : About storage configuration

Ansible Playbook used for doing the basic OS configuration (setup_picluster.yml) is able to configure two different storage setups (dedicated disks or centralized SAN) depending on the value of the variable centralized_san located in ansible/group_vars/all.yml. If centralized_san is false (default value) dedicated disk setup will be applied, otherwise centralized san setup will be configured.

Centralized SAN setup assumes gateway node has a SSD disk attached (/dev/sda) that has been partitioned during server first boot (part of the cloud-init configuration) reserving 30Gb for the root partition and the rest of available disk for hosting the LUNs

Final gateway disk configuration is:
- /dev/sda1: Boot partition
- /dev/sda2: Root Filesystem
- /dev/sda3: For being used for creating LUNS (LVM partition)
LVM configuration is done by setup_picluster.yml Ansible’s playbook and the variables used in the configuration can be found in vars/centralized_san/centralized_san_target.yml: storage_volumegroups and storage_volumes variables. Sizes of the different LUNs can be tweaked to fit the size of the SSD Disk used. I used a 480GB disk so, I was able to create LUNs of 100GB for each of the nodes.
Dedicated disks setup assumes that all cluster nodes (node1-5) have a SSD disk attached that has been partitioned during server first boot (part of the cloud-init configuration) reserving 30Gb for the root partition and the rest of available disk for creating a Linux partition mounted as /storage

Final node1-5 disk configuration is:
- /dev/sda1: Boot partition
- /dev/sda2: Root filesystem
- /dev/sda3: /storage (linux partition)
/dev/sda3 partition is created during first boot, formatted (ext4) and mounted as ‘/storage’. cloud-init configuration.

Important: : About TLS Certificates configuration

Default configuration, assumes the use of Letscrypt TLS certificates and IONOS DNS for DNS01 challenge.

As an alternative, a custom CA can be created and use it to sign all certificates. The following changes need to be done:

Modify Ansible variable enable_letsencrypt to false in /ansible/picluster.yml file
Modify Kubernetes applications ingress.tlsIssuer (/argocd/system/<app>/values.yaml) to ca instead of letsencrypt.

Vault credentials generation

Generate ansible vault variable file (var/vault.yml) containing all credentials/passwords. Random generated passwords will be generated for all cluster services.

Execute the following command:

make ansible-credentials

Credentials for external cloud services (IONOS DNS API credentials) are asked during the execution of the playbook.

Cluster nodes setup

Update Raspberry Pi firmware

Update firmware in all Raspberry-PIs following the procedure described in “Raspberry PI firmware update”

Install gateway node

Install gateway Operating System on Rapberry PI.

The installation procedure followed is the described in “Ubuntu OS Installation” using cloud-init configuration files (user-data and network-config) for gateway.

user-data depends on the storage architectural option selected::

Dedicated Disks	Centralized SAN
user-data	user-data

network-config is the same in both architectures:

Network configuration
network-config

Warning: About SSH keys

Before applying the cloud-init files of the table above, remember to change the following

user-data file:
- UNIX privileged user, ricsanfre, can be changed.
- ssh_authorized_keys field for defaul user (ricsanfre). Your own ssh public keys, created during pimaster control node preparation, must be included.
- timezone and locale can be changed as well to fit your environment.
network-config file: to fit yor home wifi network
- Replace and by your home wifi credentials
- IP address (192.168.0.11 in the sample file ), and your home network gateway (192.168.0.1 in the sample file)

Configure gateway node

For automatically execute basic OS setup tasks and configuration of gateway’s services (DNS, DHCP, NTP, Firewall, etc.), execute the command:

make gateway-setup

Install cluster nodes.

Once gateway is up and running the rest of the nodes can be installed and connected to the LAN switch, so they can obtain automatic network configuration via DHCP.

Install node1-5 Operating System on Raspberry Pi

Follow the installation procedure indicated in “Ubuntu OS Installation” using the corresponding cloud-init configuration files (user-data and network-config) depending on the storage setup selected. Since DHCP is used there is no need to change default /boot/network-config file located in the ubuntu image.

Dedicated Disks	Centralized SAN
user-data	user-data

In above user-data files, hostname field need to be changed for each node (node1-node5).

Warning: About SSH keys

Before applying the cloud-init files of the table above, remember to change the following

user-data file:
- UNIX privileged user, ricsanfre, can be changed.
- ssh_authorized_keys field for default user (ricsanfre). Your own ssh public keys, created during pimaster control node preparation, must be included.
- timezone and locale can be changed as well to fit your environment.

Configure cluster nodes

For automatically execute basic OS setup tasks (DNS, DHCP, NTP, etc.), execute the command:

make nodes-setup

Configuring external services (Minio and Hashicorp Vault)

Install and configure S3 Storage server (Minio), and Secret Manager (Hashicorp Vault) running the command:

make external-services

Ansible Playbook assumes S3 server is installed in node1 and Hashicorp Vault in gateway.

Note: All Ansible vault credentials (vault.yml) are also stored in Hashicorp Vault

Configuring OS level backup (restic)

Automate backup tasks at OS level with restic in all nodes (node1-node5 and gateway) running the command:

make configure-os-backup

Minio S3 server running in node1 will be used as backup backend.

Note:

List of directories to be backed up by restic in each node can be found in variables file var/all.yml: restic_backups_dirs

Variable restic_clean_service which configure and schedule restic’s purging activities need to be set to “true” only in one of the nodes. Defaul configuration set gateway as the node for executing these tasks.

Kubernetes Applications (GitOps)

ArgoCD is used to deploy automatically packaged applications contained in the repository. These applications are located in /argocd directory.

Modify Root application (App of Apps pattern) to point to your own repository

Edit file /argocd/bootstrap/root/values.yaml.

gitops.repo should point to your own cloned repository.
```
gitops:
  repo: https://github.com/<your-user>/pi-cluster 
```
Tune parameters of the different packaged Applications to meet your specific configuration

Edit values.yaml file of the different applications located in /argocd/system directory.

K3S

K3S Installation

To install K3S cluster, execute the command:

make k3s-install

K3S Bootstrap

To bootstrap the cluster, run the command:

make k3s-bootstrap

Argo CD will be installed and it will automatically deploy all cluster applications automatically from git repo

argocd\bootstrap\root: Containing root application (App of Apss ArgoCD pattern)
argocd\system\<app>: Containing manifest files for application

K3s Cluster reset

If you mess anything up in your Kubernetes cluster, and want to start fresh, the K3s Ansible playbook includes a reset playbook, that you can use to remove the installation of K3S:

make k3s-reset

Shutting down the Raspberry Pi Cluster

To automatically shut down the Raspberry PI cluster, Ansible can be used.

Kubernetes graceful node shutdown feature is enabled in the culster. This feature is documented here. and it ensures that pods follow the normal pod termination process during the node shutdown.

For doing a controlled shutdown of the cluster execute the following commands

Step 1: Shutdown K3S workers nodes:
```
make shutdown-k3s-worker
```
Step 2: Shutdown K3S master nodes:
```
make shutdown-k3s-master
```
Step 3: Shutdown gateway node:
```
make shutdown-gateway
```

shutdown commands connects to each Raspberry PI in the cluster and execute the command sudo shutdown -h 1m, commanding the raspberry-pi to shutdown in 1 minute.

After a few minutes, all raspberry pi will be shutdown. You can notice that when the Switch ethernet ports LEDs are off. Then it is safe to unplug the Raspberry PIs.

Updating Ubuntu packages

To automatically update Ubuntu OS packages, run the following command:

make os-upgrade

This playbook automatically updates OS packages to the latest stable version and it performs a system reboot if needed.

Last Update: May 15, 2023