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Bootstrapping the etcd Cluster

Kubernetes components are stateless and store cluster state in etcd. In this lab you will bootstrap a three node etcd cluster and configure it for high availability and secure remote access.

Prerequisites

The commands in this lab must be run on each controller instance: controller-0, controller-1, and controller-2. Login to each controller instance:

gcloud

gcloud compute ssh controller-0

az

az ssh vm --name controller-0 --local-user azureuser

ssh -i $HOME/.ssh/k8sthehardway azureuser@$(az vm show -d --name controller-0 --query "publicIps" -o tsv)

Running commands in parallel with tmux

tmux can be used to run commands on multiple compute instances at the same time. See the Running commands in parallel with tmux section in the Prerequisites lab.

Bootstrapping an etcd Cluster Member

Download and Install the etcd Binaries

Download the official etcd release binaries from the etcd GitHub project:

wget -q --show-progress --https-only --timestamping \
  "https://github.com/etcd-io/etcd/releases/download/v3.4.15/etcd-v3.4.15-linux-amd64.tar.gz"

Extract and install the etcd server and the etcdctl command line utility:

tar -xvf etcd-v3.4.15-linux-amd64.tar.gz
sudo mv etcd-v3.4.15-linux-amd64/etcd* /usr/local/bin/

Configure the etcd Server

sudo mkdir -p /etc/etcd /var/lib/etcd
sudo chmod 700 /var/lib/etcd
sudo cp ca.pem kubernetes-key.pem kubernetes.pem /etc/etcd/

The instance internal IP address will be used to serve client requests and communicate with etcd cluster peers. Retrieve the internal IP address for the current compute instance:

gcloud

INTERNAL_IP=$(curl -s -H "Metadata-Flavor: Google" \
  http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/ip)

az

sudo apt-get update
sudo apt-get install -y jq
INTERNAL_IP=$(curl -s -H Metadata:true --noproxy "*" "http://169.254.169.254/metadata/instance?api-version=2021-02-01" | jq -r '.network.interface[0].ipv4.ipAddress[0].privateIpAddress')

Each etcd member must have a unique name within an etcd cluster. Set the etcd name to match the hostname of the current compute instance:

ETCD_NAME=$(hostname -s)

Create the etcd.service systemd unit file:

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

[Service]
Type=notify
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://10.240.0.10:2380,controller-1=https://10.240.0.11:2380,controller-2=https://10.240.0.12:2380 \\
  --initial-cluster-state new \\
  --data-dir=/var/lib/etcd
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF

Start the etcd Server

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

Remember to run the above commands on each controller node: controller-0, controller-1, and controller-2.

Verification

List the etcd cluster members:

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

output

3a57933972cb5131, started, controller-2, https://10.240.0.12:2380, https://10.240.0.12:2379, false
f98dc20bce6225a0, started, controller-0, https://10.240.0.10:2380, https://10.240.0.10:2379, false
ffed16798470cab5, started, controller-1, https://10.240.0.11:2380, https://10.240.0.11:2379, false

Next: Bootstrapping the Kubernetes Control Plane

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