Skip to content

Latest commit

 

History

History
143 lines (106 loc) · 4.68 KB

07-bootstrapping-etcd.md

File metadata and controls

143 lines (106 loc) · 4.68 KB
Raw

Bootstrapping the etcd Cluster

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

If you examine the command line arguments passed to etcd in its unit file, you should recognise some of the certificates and keys created in earlier sections of this course.

Prerequisites

The commands in this lab must be run on each controller instance: controlplane01, and controlplane02. Login to each of these using an SSH terminal.

Running commands in parallel with tmux

tmux can be used to run commands on multiple compute instances at the same time.

Bootstrapping an etcd Cluster Member

Download and Install the etcd Binaries

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

ETCD_VERSION="v3.5.9"
wget -q --show-progress --https-only --timestamping \
  "https://github.com/coreos/etcd/releases/download/${ETCD_VERSION}/etcd-${ETCD_VERSION}-linux-${ARCH}.tar.gz"

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

{
  tar -xvf etcd-${ETCD_VERSION}-linux-${ARCH}.tar.gz
  sudo mv etcd-${ETCD_VERSION}-linux-${ARCH}/etcd* /usr/local/bin/
}

Configure the etcd Server

Copy and secure certificates. Note that we place ca.crt in our main PKI directory and link it from etcd to not have multiple copies of the cert lying around.

{
  sudo mkdir -p /etc/etcd /var/lib/etcd /var/lib/kubernetes/pki
  sudo cp etcd-server.key etcd-server.crt /etc/etcd/
  sudo cp ca.crt /var/lib/kubernetes/pki/
  sudo chown root:root /etc/etcd/*
  sudo chmod 600 /etc/etcd/*
  sudo chown root:root /var/lib/kubernetes/pki/*
  sudo chmod 600 /var/lib/kubernetes/pki/*
  sudo ln -s /var/lib/kubernetes/pki/ca.crt /etc/etcd/ca.crt
}

The instance internal IP address will be used to serve client requests and communicate with etcd cluster peers.
Retrieve the internal IP address of the controlplane(etcd) nodes, and also that of controlplane01 and controlplane02 for the etcd cluster member list

CONTROL01=$(dig +short controlplane01)
CONTROL02=$(dig +short controlplane02)

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]
ExecStart=/usr/local/bin/etcd \\
  --name ${ETCD_NAME} \\
  --cert-file=/etc/etcd/etcd-server.crt \\
  --key-file=/etc/etcd/etcd-server.key \\
  --peer-cert-file=/etc/etcd/etcd-server.crt \\
  --peer-key-file=/etc/etcd/etcd-server.key \\
  --trusted-ca-file=/etc/etcd/ca.crt \\
  --peer-trusted-ca-file=/etc/etcd/ca.crt \\
  --peer-client-cert-auth \\
  --client-cert-auth \\
  --initial-advertise-peer-urls https://${PRIMARY_IP}:2380 \\
  --listen-peer-urls https://${PRIMARY_IP}:2380 \\
  --listen-client-urls https://${PRIMARY_IP}:2379,https://127.0.0.1:2379 \\
  --advertise-client-urls https://${PRIMARY_IP}:2379 \\
  --initial-cluster-token etcd-cluster-0 \\
  --initial-cluster controlplane01=https://${CONTROL01}:2380,controlplane02=https://${CONTROL02}: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: controlplane01, and controlplane02.

Verification

List the etcd cluster members.

After running the abovre commands on both controlplane nodes, run the following on either or both of controlplane01 and controlplane02

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

Output will be similar to this

45bf9ccad8d8900a, started, controlplane02, https://192.168.56.12:2380, https://192.168.56.12:2379
54a5796a6803f252, started, controlplane01, https://192.168.56.11:2380, https://192.168.56.11:2379

Reference: https://kubernetes.io/docs/tasks/administer-cluster/configure-upgrade-etcd/#starting-etcd-clusters

Next: Bootstrapping the Kubernetes Control Plane
Prev: Generating the Data Encryption Config and Key