151 lines
3.4 KiB
Markdown
151 lines
3.4 KiB
Markdown
# Bootstrapping a H/A etcd cluster
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In this lab you will bootstrap a 3 node etcd cluster. The following virtual machines will be used:
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* etcd0
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* etcd1
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* etcd2
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## Why
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All Kubernetes components are stateless which greatly simplifies managing a Kubernetes cluster. All state is stored
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in etcd, which is a database and must be treated special. etcd is being run on a dedicated set of machines for the
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following reasons:
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* The etcd lifecycle is not tied to Kubernetes. We should be able to upgrade etcd independently of Kubernetes.
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* Scaling out etcd is different than scaling out the Kubernetes Control Plane.
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* Prevent other applications from taking up resources (CPU, Memory, I/O) required by etcd.
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## Provision the etcd Cluster
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Run the following commands on `etcd0`, `etcd1`, `etcd2`:
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Move the TLS certificates in place:
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```
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sudo mkdir -p /etc/etcd/
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```
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```
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sudo mv ca.pem kubernetes-key.pem kubernetes.pem /etc/etcd/
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```
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Download and install the etcd binaries:
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```
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wget https://github.com/coreos/etcd/releases/download/v3.0.8/etcd-v3.0.8-linux-amd64.tar.gz
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```
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```
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tar -xvf etcd-v3.0.8-linux-amd64.tar.gz
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```
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```
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sudo cp etcd-v3.0.8-linux-amd64/etcd* /usr/bin/
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```
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```
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sudo mkdir -p /var/lib/etcd
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```
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Create the etcd systemd unit file:
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```
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cat > etcd.service <<"EOF"
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[Unit]
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Description=etcd
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Documentation=https://github.com/coreos
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[Service]
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ExecStart=/usr/bin/etcd --name ETCD_NAME \
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--cert-file=/etc/etcd/kubernetes.pem \
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--key-file=/etc/etcd/kubernetes-key.pem \
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--peer-cert-file=/etc/etcd/kubernetes.pem \
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--peer-key-file=/etc/etcd/kubernetes-key.pem \
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--trusted-ca-file=/etc/etcd/ca.pem \
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--peer-trusted-ca-file=/etc/etcd/ca.pem \
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--initial-advertise-peer-urls https://INTERNAL_IP:2380 \
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--listen-peer-urls https://INTERNAL_IP:2380 \
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--listen-client-urls https://INTERNAL_IP:2379,http://127.0.0.1:2379 \
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--advertise-client-urls https://INTERNAL_IP:2379 \
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--initial-cluster-token etcd-cluster-0 \
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--initial-cluster etcd0=https://10.240.0.10:2380,etcd1=https://10.240.0.11:2380,etcd2=https://10.240.0.12:2380 \
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--initial-cluster-state new \
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--data-dir=/var/lib/etcd
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Restart=on-failure
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RestartSec=5
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[Install]
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WantedBy=multi-user.target
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EOF
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```
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### Set The Internal IP Address
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#### GCE
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```
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INTERNAL_IP=$(curl -s -H "Metadata-Flavor: Google" \
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http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/ip)
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```
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#### AWS
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```
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INTERNAL_IP=$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)
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```
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---
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Set the etcd name:
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```
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ETCD_NAME=etcd$(echo $INTERNAL_IP | cut -c 11)
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```
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```
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sed -i s/INTERNAL_IP/${INTERNAL_IP}/g etcd.service
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```
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```
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sed -i s/ETCD_NAME/${ETCD_NAME}/g etcd.service
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```
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```
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sudo mv etcd.service /etc/systemd/system/
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```
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Start etcd:
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```
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sudo systemctl daemon-reload
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sudo systemctl enable etcd
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sudo systemctl start etcd
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```
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### Verification
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```
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sudo systemctl status etcd --no-pager
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```
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> Remember to run these steps on `etcd0`, `etcd1`, and `etcd2`
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## Verification
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Once all 3 etcd nodes have been bootstrapped verify the etcd cluster is healthy:
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* SSH to etcd0 and run the following commands:
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```
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etcdctl --ca-file=/etc/etcd/ca.pem cluster-health
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```
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```
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member 3a57933972cb5131 is healthy: got healthy result from https://10.240.0.12:2379
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member f98dc20bce6225a0 is healthy: got healthy result from https://10.240.0.10:2379
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member ffed16798470cab5 is healthy: got healthy result from https://10.240.0.11:2379
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cluster is healthy
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```
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