# Bootstrapping a H/A etcd cluster In this lab you will bootstrap a 3 node etcd cluster. The following virtual machines will be used: * etcd0 * etcd1 * etcd2 ## Why All Kubernetes components are stateless which greatly simplifies managing a Kubernetes cluster. All state is stored in etcd, which is a database and must be treated special. etcd is being run on a dedicated set of machines for the following reasons: * The etcd lifecycle is not tied to Kubernetes. We should be able to upgrade etcd independently of Kubernetes. * Scaling out etcd is different than scaling out the Kubernetes Control Plane. * Prevent other applications from taking up resources (CPU, Memory, I/O) required by etcd. ## Provision the etcd Cluster Run the following commands on `etcd0`, `etcd1`, `etcd2`: Move the TLS certificates in place: ``` sudo mkdir -p /etc/etcd/ ``` ``` sudo mv ca.pem kubernetes-key.pem kubernetes.pem /etc/etcd/ ``` Download and install the etcd binaries: ``` wget https://github.com/coreos/etcd/releases/download/v3.0.8/etcd-v3.0.8-linux-amd64.tar.gz ``` ``` tar -xvf etcd-v3.0.8-linux-amd64.tar.gz ``` ``` sudo cp etcd-v3.0.8-linux-amd64/etcd* /usr/bin/ ``` ``` sudo mkdir -p /var/lib/etcd ``` Create the etcd systemd unit file: ``` cat > etcd.service <<"EOF" [Unit] Description=etcd Documentation=https://github.com/coreos [Service] ExecStart=/usr/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 \ --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 etcd0=https://10.240.0.10:2380,etcd1=https://10.240.0.11:2380,etcd2=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 ``` ### Set The Internal IP Address #### GCE ``` INTERNAL_IP=$(curl -s -H "Metadata-Flavor: Google" \ http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/ip) ``` #### AWS ``` INTERNAL_IP=$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4) ``` --- Set the etcd name: ``` ETCD_NAME=etcd$(echo $INTERNAL_IP | cut -c 11) ``` ``` sed -i s/INTERNAL_IP/${INTERNAL_IP}/g etcd.service ``` ``` sed -i s/ETCD_NAME/${ETCD_NAME}/g etcd.service ``` ``` sudo mv etcd.service /etc/systemd/system/ ``` Start etcd: ``` sudo systemctl daemon-reload sudo systemctl enable etcd sudo systemctl start etcd ``` ### Verification ``` sudo systemctl status etcd --no-pager ``` > Remember to run these steps on `etcd0`, `etcd1`, and `etcd2` ## Verification Once all 3 etcd nodes have been bootstrapped verify the etcd cluster is healthy: * SSH to etcd0 and run the following commands: ``` etcdctl --ca-file=/etc/etcd/ca.pem cluster-health ``` ``` member 3a57933972cb5131 is healthy: got healthy result from https://10.240.0.12:2379 member f98dc20bce6225a0 is healthy: got healthy result from https://10.240.0.10:2379 member ffed16798470cab5 is healthy: got healthy result from https://10.240.0.11:2379 cluster is healthy ```