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The ungleich kubernetes infrastructure » History » Revision 25

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Nico Schottelius, 08/14/2021 07:14 PM


The ungleich kubernetes infrastructure and ungleich kubernetes manual

Status

This document is pre-production. This document is to become the ungleich kubernetes infrastructure overview as well as the ungleich kubernetes manual.

k8s clusters

Cluster Purpose Notes
c0.k8s.ooo Dev
c1.k8s.ooo Dev p6
c2.k8s.ooo Demo/Semiprod
c3.k8s.ooo Dev p6
c4.k8s.ooo active-dev p7
p6.k8s.ooo planned
p10.k8s.ooo production

Typical init procedure:

  • Single control plane: kubeadm init --config bootstrap/XXX/kubeadm.yaml
  • Multi control plane (HA): kubeadm init --config bootstrap/XXX/kubeadm.yaml --upload-certs

General architecture and components overview

  • All k8s clusters are IPv6 only
  • We use BGP peering to propagate podcidr and serviceCidr networks to our infrastructure
  • The main / public repository is ungleich-k8s

ungleich kubernetes infrastructure v1

We are using the following components:

  • Calico as a CNI with BGP, IPv6 only, no encapsulation
    • Needed for basic networking
  • kubernetes-secret-generator for creating secrets
    • Needed so that secrets are not stored in the git repository, but only in the cluster
  • ungleich-certbot
    • Needed to get letsencrypt certificates for services
  • rook with ceph rbd + cephfs for storage
    • rbd for almost everything, ReadWriteOnce
    • cephfs for smaller things, multi access ReadWriteMany
    • Needed for providing persistent storage
  • flux v2
    • Needed to manage resources automatically

Persistent storage setup

  • 3 or 5 monitors

Cluster types

Type/Feature Development Production
Min No. nodes 3 (1 master, 3 worker) 5 (3 master, 3 worker)
Recommended minimum 4 (dedicated master, 3 worker) 8 (3 master, 5 worker)
Separation of control plane optional recommended
Persistent storage required required
Number of storage monitors 3 5

Operations

Installing a new k8s cluster

  • Decide on the cluster name (usually cX.k8s.ooo), X counting upwards
  • Use cdist to configure the nodes with requirements like crio
  • Decide between single or multi node control plane setups (see below)
  • Setup DNS delegation and glue records:
    • kube-dns.kube-system.svc.cX AAAA ...
    • kube-dns.kube-system.svc.cX A ...
    • cX NS kube-dns.kube-system.svc.cX

Open Issues / To be discussed

Updated by Nico Schottelius almost 3 years ago · 25 revisions