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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 master instance: master-0, master-1, and master-2. Login to each master instance using ssh command. Example:

$ aws ec2 describe-instances --filters Name=vpc-id,Values=vpc-xxxxxxxxxxxxxxxxx \
  --query 'Reservations[].Instances[].[Tags[?Key==`Name`].Value | [0],InstanceId,Placement.AvailabilityZone,PrivateIpAddress,PublicIpAddress,State.Name]' \
  --output text | sort | grep master
master-0        i-xxxxxxxxxxxxxxxxx     ap-northeast-1c 10.240.0.10     xx.xxx.xxx.xxx  running
...

$ ssh -i ~/.ssh/your_ssh_key ubuntu@xx.xxx.xxx.xxx

Running commands in parallel with tmux

tmux can be used to run commands on multiple EC2 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:

master-x $ wget -q --show-progress --https-only --timestamping \
  "https://github.com/etcd-io/etcd/releases/download/v3.4.0/etcd-v3.4.0-linux-amd64.tar.gz"

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

master-x $ tar -xvf etcd-v3.4.0-linux-amd64.tar.gz
master-x $ sudo mv etcd-v3.4.0-linux-amd64/etcd* /usr/local/bin/

Results:

master-x $ ls /usr/local/bin/
etcd  etcdctl

Configure the etcd Server

master-x $ sudo mkdir -p /etc/etcd /var/lib/etcd
master-x $ 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 EC2 instance via instance metadata on EC2 instances:

Example:

master-0 $ curl 169.254.169.254/latest/meta-data/local-ipv4
10.240.0.10

Set INTERNAL_IP environemnt variable:

master-x $ INTERNAL_IP=$(curl 169.254.169.254/latest/meta-data/local-ipv4)

Each etcd member must have a unique name within an etcd cluster. Set the etcd name to match the hostname of the current EC2 instance:

Example:

master-0 $ hostname -s
master-0

Set ETCD_NAME environemnt variable:

master-x $ ETCD_NAME=$(hostname -s)

Create the etcd.service systemd unit file:

master-x $ 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 master-0=https://10.240.0.10:2380,master-1=https://10.240.0.11:2380,master-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

master-x $ sudo systemctl daemon-reload
master-x $ sudo systemctl enable etcd
master-x $ sudo systemctl start etcd

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

Verify etcd servers are running as systemd services.

master-x $ systemctl status etcd.service
● etcd.service - etcd
   Loaded: loaded (/etc/systemd/system/etcd.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2020-01-20 18:01:29 UTC; 21s ago
   ...

Verification

List the etcd cluster members:

master-0 $ 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

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

Next: Bootstrapping the Kubernetes Control Plane