kubernetes-the-hard-way/docs/07-bootstrapping-etcd.md

# Bootstrapping the etcd Cluster

Kubernetes components are stateless and store cluster state in [etcd](https://etcd.io/). In this lab you will bootstrap a two 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: `master-1`, and `master-2`. Login to each of these using an SSH terminal.

### Running commands in parallel with tmux

[tmux](https://github.com/tmux/tmux/wiki) 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](https://github.com/etcd-io/etcd) GitHub project:

[//]: # (host:master-1-master2)


```bash
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-amd64.tar.gz"
```

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

```bash
{
  tar -xvf etcd-${ETCD_VERSION}-linux-amd64.tar.gz
  sudo mv etcd-${ETCD_VERSION}-linux-amd64/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.

```bash
{
  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.<br>
Retrieve the internal IP address of the master(etcd) nodes, and also that of master-1 and master-2 for the etcd cluster member list

```bash
INTERNAL_IP=$(ip addr show enp0s8 | grep "inet " | awk '{print $2}' | cut -d / -f 1)
MASTER_1=$(dig +short master-1)
MASTER_2=$(dig +short master-2)
```

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:

```bash
ETCD_NAME=$(hostname -s)
```

Create the `etcd.service` systemd unit file:

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

[Service]
ExecStart=/usr/local/bin/etcd \\
  --name ${ETCD_NAME} \\
  --cert-file=/etc/etcd/etcd-server.crt \\
  --key-file=/etc/etcd/etcd-server.key \\
  --peer-cert-file=/etc/etcd/etcd-server.crt \\
  --peer-key-file=/etc/etcd/etcd-server.key \\
  --trusted-ca-file=/etc/etcd/ca.crt \\
  --peer-trusted-ca-file=/etc/etcd/ca.crt \\
  --peer-client-cert-auth \\
  --client-cert-auth \\
  --initial-advertise-peer-urls https://${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://${INTERNAL_IP}:2379 \\
  --initial-cluster-token etcd-cluster-0 \\
  --initial-cluster master-1=https://${MASTER_1}:2380,master-2=https://${MASTER_2}: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

```bash
{
  sudo systemctl daemon-reload
  sudo systemctl enable etcd
  sudo systemctl start etcd
}
```

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

## Verification

[//]: # (sleep:5)

List the etcd cluster members:

```bash
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

```
45bf9ccad8d8900a, started, master-2, https://192.168.56.12:2380, https://192.168.56.12:2379
54a5796a6803f252, started, master-1, 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

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Next: [Bootstrapping the Kubernetes Control Plane](08-bootstrapping-kubernetes-controllers.md)