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07-bootstrapping-etcd.md

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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 using the az command to find its public IP and ssh to it. Example:

CONTROLLER="controller-0"
PUBLIC_IP_ADDRESS=$(az network public-ip show -g kubernetes \
  -n ${CONTROLLER}-pip --query "ipAddress" -otsv)

ssh kuberoot@${PUBLIC_IP_ADDRESS}

Bootstrapping an etcd Cluster Member

Download and Install the etcd Binaries

Download the official etcd release binaries from the etcd-io/etcd GitHub project:

wget -q --show-progress --https-only --timestamping \
  "https://github.com/etcd-io/etcd/releases/download/v3.3.13/etcd-v3.3.13-linux-amd64.tar.gz"

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

{
  tar -xvf etcd-v3.3.13-linux-amd64.tar.gz
  sudo mv etcd-v3.3.13-linux-amd64/etcd* /usr/local/bin/
}

Configure the etcd Server

{
  sudo mkdir -p /etc/etcd /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:

INTERNAL_IP=$(ip addr show eth0 | grep -oP '(?<=inet\s)\d+(\.\d+){3}')

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 > etcd.service <<EOF
[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,http://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 mv etcd.service /etc/systemd/system/
{
  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://${INTERNAL_IP}: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
f98dc20bce6225a0, started, controller-0, https://10.240.0.10:2380, https://10.240.0.10:2379
ffed16798470cab5, started, controller-1, https://10.240.0.11:2380, https://10.240.0.11:2379

Next: Bootstrapping the Kubernetes Control Plane