06-ETCD-in-HA.md

ETCD in HA

Take me to Lecture

In this section, we will discuss about ETCD in HA mode

Objectives

• What is ETCD?
• What is a key-value store?
• How to get started quickly?
• How to operate ETCD?
• What is distributed system?
• How ETCD operates?
• RAFT Protocol
• Best Practices on number of nodes

Quorum

• Quorum is the minimum number of nodes that must be available for the cluster to function properly or make a successful right in case of 3, we know its 2.

• For any given number of nodes, the quorum is the total number of nodes divided by 2 + 1.

  

  

Getting Started

• Download the binary

  $ wget -q --http-only https://github.com/coreos/etcd/releases/download/v3.3.9/etcd-v3.3.9-linux-amd64.tar.gz
  

• Extract it

  $ tar -xvzf etcd-v3.3.9-linux-amd64.tar.gz
  

• Move the etcd binaries to /usr/local/bin/

  $ mv etcd-v3.3.9-linux-amd64/etcd* /usr/local/bin/
  

• Create directories

  $ mkdir -p /etc/etcd /var/lib/etcd
  

• Copy TLS certs

  $ cp ca.pem kubernetes-key.pem kubernetes.pem /etc/etcd/
  

Configure the etcd service

ETCDCTL

• The etcdctl utility has 2 versions

  • V2
  • V3

• Set etcdctl_api environment variable to 3

  $ export ETCDCTL_API=3
  

Number of Nodes

Our Lab Design

K8s Reference Docs

• https://github.com/etcd-io/etcd/releases