Infra Requirements

Overview

This page discusses the infrastructure requirements for DIGIT services. It also explains why DIGIT services are containerised and deployed on Kubernetes.

Requirements

DIGIT Infra is abstracted to **[Kubernetes](https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/) which is an open-source containers orchestration platform that helps in abstracting variety of infra types that are being available across each state, like Physical, VMs, on-premises clouds(VMware, OpenStack, Nutanix, etc.), commercial clouds (Google, AWS, Azure, etc.), SDC and NIC into a standard infra type. Essentially it unifies various infra types into a standard and single type of infrastructure and thus DIGIT becomes multi-cloud supported, portable, extensible, high-performant and scalable** containerized workloads and services. This facilitates both declarative configuration and automation. Kubernetes services, eco-system, support and tools are widely available.

The basic need to provision Kubernetes Cluster

Kubernetes as such is a set of components that designated jobs of scheduling, controlling, monitoring

Master Cluster

• 3 or more machines running one of:

  • Ubuntu 16.04+

  • Debian 9

  • CentOS 7

  • RHEL 7

  • Container Linux (tested with 1576.4.0)

• 4 GB or more of RAM per machine (any less will leave little room for your apps)

• 2 CPUs or more

User Cluster

• 3 or more machines running one of:

  • Ubuntu 16.04+

  • Debian 9

  • CentOS 7

  • RHEL 7

  • Container Linux (tested with 1576.4.0)

• 2 GB or more of RAM per machine (any less will leave little room for your apps)

• 2 CPUs or more

• Full network connectivity between all machines in the cluster (public or private network is fine)

• Unique hostname, MAC address, and product_uuid for every node. Click here for more details.

• Certain ports are open on your machines. See below for more details

• Swap disabled. You MUST disable swap in order for the Kubelet to work properly

Verify the MAC Address and product_uuid Are Unique for Every Node

• You can get the MAC address of the network interfaces using the command ip link or ifconfig -a

• The product_uuid can be checked by using the command sudo cat /sys/class/dmi/id/product_uuid

It is very likely that hardware devices will have unique addresses, although some virtual machines may have identical values. Kubernetes uses these values to uniquely identify the nodes in the cluster. If these values are not unique to each node, the installation process may fail.

Check Network Adapters

If you have more than one network adapter, and your Kubernetes components are not reachable on the default route, we recommend you add IP route(s) so Kubernetes cluster addresses go via the appropriate adapter.

Check Required Ports

Master Cluster Master Node(s)

Protocol	Direction	Port Range	Purpose
TCP	Inbound	6443*	Kubernetes API server
TCP	Inbound	2379-2380	etcd server client API
TCP	Inbound	10250	kubelet API
TCP	Inbound	10251	kube-scheduler
TCP	Inbound	10252	kube-controller-manager
TCP	Inbound	10255	Read-only kubelet API

Worker Node(s)& User Cluster Worker Nodes

Protocol	Direction	Port Range	Purpose
TCP	Inbound	10250	kubelet API
TCP	Inbound	10255	Read-only kubelet API
TCP	Inbound	30000-32767	NodePort Services**

** Default port range for NodePort Services.

Any port numbers marked with * are overridable, so you will need to ensure any custom ports you provide are also open.