Adding support to two different cluster storage architectures (dedicated disks and SAN iSCSI disks)

[ricsanfre]

Changes Introduced

• New hardware:
  • 3 SSD disk (240 GB)
  • 3 SATA to USB adapters
  • SSD Rack Case
• Cluster hardware reconfiguration
  • Add a SSD disk to each node of the cluster node to improve performance. Reusing 480 GB SSD disk used in the previous architecture as centralized SAN, this disk will be attached to node1 to configure it as backup node, for implementing PR Design and implement cluster backup architecture #6
  • Boot and running from SSD will increase computing performance of each Raspberry PI (SSD better I/O metrics than Flash Disk)
  • Use of local storage (dedicated partition within SSD disk) by Kubernetes Distributed Solution (Longhorn) instead of iSCSI volumes will increase performance of pods running on the cluster.
• Add automation support for two storage architectures (dedicated_disks and centralized_san). Updating anbible playbooks and roles involved in the pi cluster setup and cloud-init files
  • Cloud-init files changes:
    • Files refactoring and simplification (removing unnecessary lines)
    • Security hardening (remove default ubuntu user, enable only SSH access)
    • Automatic partition of SSD disk in boot time: leaving root file partition with 30GB and reusing the rest for local storage.
    • Maintaining cloud-init files versions for the two storage architectures: dedicated disks and centralized_san
  • Ansible Playbooks:
    • setup_pi.yml playbook adaptation to support two different storage architectures. Storage-related ansible variables removed from hosts/groups variable files and put into dedicated files in vars directory. Different var files loaded by ansible playbook in run-time depending on the storage architecture selected.
    • Yamllint refactoring: Solving yamllint issues with ansible playbooks and kubernetes manifest templates.
• Documentation:
  • Updated installation documentation

Issues fixed by this PR:

• Fix Redesign cluster architecture (new Hardware) #11

[ricsanfre]

Minor modifications