3.4 KiB
3.4 KiB
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
, andetcd2
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