Bootstrapping an etcd Cluster for Kubernetes

1.5 hours
  • 2 Learning Objectives

About this Hands-on Lab

Kubernetes uses etcd to reliably store data in a distributed fashion. One of the necessary steps for setting up a Kubernetes cluster from scratch is to configure an etcd cluster that spans all of the Kubernetes control nodes. In this activity, you will learn how to install and configure an etcd cluster in preparation for setting up Kubernetes. After completing this exercise, you should be able to stand up a multi-node etcd cluster that is capable of supporting the Kubernetes control plane.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Install the etcd binary on both control nodes.

Do the following on both Kubernetes control nodes:

wget -q --show-progress --https-only --timestamping 
  "https://github.com/coreos/etcd/releases/download/v3.3.5/etcd-v3.3.5-linux-amd64.tar.gz"
tar -xvf etcd-v3.3.5-linux-amd64.tar.gz
sudo mv etcd-v3.3.5-linux-amd64/etcd* /usr/local/bin/
Configure and start the etcd service on both control nodes.

Do the following on both Kubernetes control nodes:

sudo mkdir -p /etc/etcd /var/lib/etcd
sudo cp ca.pem kubernetes-key.pem kubernetes.pem /etc/etcd/

Set the ETCD_NAME variable. Be sure to replace the placeholder in this command with controller-0 or controller-1, as appropriate for each server.

ETCD_NAME=<controller-0 or controller-1>
INTERNAL_IP=$(curl http://169.254.169.254/latest/meta-data/local-ipv4)
CONTROLLER_0_INTERNAL_IP=<controller 0 private ip>
CONTROLLER_1_INTERNAL_IP=<controller 1 private ip>

Create the etcd systemd unit file with the following command. Be sure to replace the placeholders in –name and –initial-cluster with real values.

cat << EOF | sudo tee /etc/systemd/system/etcd.service
[Unit]
Description=etcd
Documentation=https://github.com/coreos

[Service]
ExecStart=/usr/local/bin/etcd \
  --name ${ETCD_NAME} \
  --cert-file=/etc/etcd/kubernetes.pem \
  --key-file=/etc/etcd/kubernetes-key.pem \
  --peer-cert-file=/etc/etcd/kubernetes.pem \
  --peer-key-file=/etc/etcd/kubernetes-key.pem \
  --trusted-ca-file=/etc/etcd/ca.pem \
  --peer-trusted-ca-file=/etc/etcd/ca.pem \
  --peer-client-cert-auth \
  --client-cert-auth \
  --initial-advertise-peer-urls https://${INTERNAL_IP}:2380 \
  --listen-peer-urls https://${INTERNAL_IP}:2380 \
  --listen-client-urls https://${INTERNAL_IP}:2379,https://127.0.0.1:2379 \
  --advertise-client-urls https://${INTERNAL_IP}:2379 \
  --initial-cluster-token etcd-cluster-0 \
  --initial-cluster controller-0=https://${CONTROLLER_0_INTERNAL_IP}:2380,controller-1=https://${CONTROLLER_1_INTERNAL_IP}:2380 \
  --initial-cluster-state new \
  --data-dir=/var/lib/etcd
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

Start and enable the etcd service:

sudo systemctl daemon-reload
sudo systemctl enable etcd
sudo systemctl start etcd

Additional Resources

Your team is working on setting up a new Kubernetes cluster. Because etcd is one of the necessary components of Kubernetes, the team needs an etcd cluster configured to run across all of the servers that will become the Kubernetes control nodes. You have been given the task of setting up an etcd cluster that will be used to support Kubernetes.

You can verify that your etcd cluster is working like this:

sudo ETCDCTL_API=3 etcdctl member list 
  --endpoints=https://127.0.0.1:2379 
  --cacert=/etc/etcd/ca.pem 
  --cert=/etc/etcd/kubernetes.pem 
  --key=/etc/etcd/kubernetes-key.pem

The output should list the two servers in your etcd cluster.

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