System Requirements

Minimum System Requirements

The minimum size for a cluster is 1 machine (node). In this case, a single machine will act as control plane (master) and will accept container workloads (worker). This kind of setup might work well for testing purposes, but might be too limited for production.

In the ideal world, master and worker nodes are separated. It is also possible to create multi-master setups for high availability cluster deployments. When Kontena Pharos cluster is installed and running, it will consume some amount of system resources. See below the minimum system requirements:

  • Master Nodes: 2GB of memory, 40GB disk
  • Worker Nodes: 2GB of memory, 40GB disk

Note! The system requirements listed in here are just bare minimum for getting the Kontena Pharos cluster up and running. In reality, the amount of memory and disk required is based on the use case and actual workloads.

Supported Machines & Operating Systems

Kontena Pharos cluster may be run on any machine (bare metal or virtual) that is capable of running one of the following operating systems on any of the supported architectures:

Operating System Architectures
CentOS 7.4 - 7.5 x86-64
Debian 9 x86-64, ARM64
Redhat Enterprise Linux 7.4 - 7.6 x86-64
Ubuntu 16.04 & 18.04 x86-64, ARM64

Required Open Ports

The following ports are used by the pharos management tool, as well as between nodes in the same cluster. These ports are all authenticated, and can safely be left open for public access if desired.

Protocol Port Service Direction Notes
TCP 22 SSH CLI => Host authenticated management channel for pharos operations using SSH keys
TCP 2379 etcd clients Master <=> Master * authenticated etcd client API using TLS client certs
TCP 2380 etcd peers Master <=> Master * authenticated etcd peers API using TLS client certs
TCP 6443 kube-apiserver Worker, CLI => Master authenticated kube API using kube TLS client certs, ServiceAccount tokens with RBAC
TCP 6783 weave control Host <=> Host * authenticated Weave peer control connections using the shared weave secret
UDP 6783 weave dataplane Host <=> Host * authenticated Weave sleeve fallback using the shared weave secret
UDP 6784 weave dataplane Host <=> Host (trusted) * unauthenticated Weave fastdp (VXLAN), only used for peers on network.trusted_subnets networks
ESP (IPSec) weave dataplane Host <=> Host * authenticated Weave fastdp (IPsec encapsulated UDP port 6784 VXLAN) using IPSec SAs established over the control channel
TCP 10250 kubelet Master, Worker => Host * authenticated kubelet API for the master node kube-apiserver (and heapster/metrics-server addons) using TLS client certs

If using the ingress-nginx addon, then TCP ports 80/443 on the worker nodes (or nodes matching addons.ingress-nginx.node_selector) must also be opened for public access.

  • * - public access is blocked if firewalld is enabled (with default rules)

Monitoring Ports

The following ports serve unauthenticated monitoring/debugging information, and are either disabled, limited to localhost-only or only expose relatively harmless information.

Protocol Port Service Hosts Status Notes
TCP 6781 weave-npc metrics All OPEN * unauthenticated /metrics
TCP 6782 weave metrics All OPEN * unauthenticated /metrics
TCP 10248 kubelet All localhost-only ?
TCP 10249 kube-proxy metrics All localhost-only ?
TCP 10251 kube-scheduler Master localhost-only ?
TCP 10252 kube-controller Master localhost-only ?
TCP 10255 kubelet read-only All disabled unauthenticated read-only /pods, various stats metrics
TCP 10256 kube-proxy healthz All OPEN * unauthenticated /healthz
TCP 18080 ingress-nginx status Workers OPEN * unauthenticated /healthz, /nginx_status and default backend
  • * - public access is blocked if firewalld is enabled (with default rules)

These ports should be restricted from external access to prevent information leaks.

Restricted Ports

The following restricted services are only accessible via localhost the nodes, and must not be exposed to any untrusted access.

Protocol Port Service Hosts Status Notes
TCP 6784 weave control All localhost-only unauthenticated weave control API

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