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etcd_cluster_setup.md

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Possible configuration for etcd clustering

For etcd cluster creation please refer https://github.com/etcd-io/etcd/tree/master/contrib/systemd/etcd3-multinode

## Steps to create a 3 node etcd cluster:

Node1:
1. sudo mkdir -p /root/hpe-etcd
   #Note: /root/hpe-etcd is the data-dir
2. sudo chown -R root:$(whoami) /root/hpe-etcd
3. sudo chmod -R a+rw /root/hpe-etcd
4. vi /etc/systemd/system/hpe-etcd-1.service

[Unit]
Description=etcd
Documentation=https://github.com/coreos/etcd

[Service]
Type=notify
Restart=always
RestartSec=5s
LimitNOFILE=40000
TimeoutStartSec=0
ExecStart=/usr/bin/etcd --name ${IP_1} --data-dir /root/hpe-etcd --listen-client-urls http://${IP_1}:23790 --advertise-client-urls http://${IP_1}:23790 --listen-peer-urls http://${IP_1}:23800 --initial-advertise-peer-urls http://${IP_1}:23800 --initial-cluster ${IP_1}=http://${IP_1}:23800,${IP_2}=http://${IP_2}:23800,${IP_3}=http://${IP_3}:23800 --initial-cluster-token my-etcd-token --initial-cluster-state new

[Install]
WantedBy=multi-user.target

5. sudo systemctl daemon-reload
6. sudo systemctl enable hpe-etcd-1.service
7. sudo systemctl start hpe-etcd-1.service

Node2:
1. sudo mkdir -p /root/hpe-etcd
2. sudo chown -R root:$(whoami) /root/hpe-etcd
3. sudo chmod -R a+rw /root/hpe-etcd
4. vi /etc/systemd/system/hpe-etcd-2.service

[Unit]
Description=etcd
Documentation=https://github.com/coreos/etcd

[Service]
Type=notify
Restart=always
RestartSec=5s
LimitNOFILE=40000
TimeoutStartSec=0
ExecStart=/usr/bin/etcd --name ${IP_2} \
    --data-dir /root/hpe-etcd \
    --listen-client-urls http://${IP_2}:23790 \
    --advertise-client-urls http://${IP_2}:23790 \
    --listen-peer-urls http://${IP_2}:23800 \
    --initial-advertise-peer-urls http://${IP_2}:23800 \
    --initial-cluster ${IP_1}=http://${IP_1}:23800,${IP_2}=http://${IP_2}:23800,${IP_3}=http://${IP_3}:23800 \
    --initial-cluster-token my-etcd-token \
    --initial-cluster-state new

[Install]
WantedBy=multi-user.target

5. sudo systemctl daemon-reload
6. sudo systemctl enable hpe-etcd-2.service
7. sudo systemctl start hpe-etcd-2.service

Node3:
1. sudo mkdir -p /root/hpe-etcd
2. sudo chown -R root:$(whoami) /root/hpe-etcd
3. sudo chmod -R a+rw /root/hpe-etcd
4. vi /etc/systemd/system/hpe-etcd-3.service

[Unit]
Description=etcd
Documentation=https://github.com/coreos/etcd

[Service]
Type=notify
Restart=always
RestartSec=5s
LimitNOFILE=40000
TimeoutStartSec=0
ExecStart=/usr/bin/etcd --name ${IP_3} \
    --data-dir /root/hpe-etcd \
    --listen-client-urls http://${IP_3}:23790 \
    --advertise-client-urls http://${IP_3}:23790 \
    --listen-peer-urls http://${IP_3}:23800 \
    --initial-advertise-peer-urls http://${IP_3}:23800 \
    --initial-cluster ${IP_1}=http://${IP_1}:23800,${IP_2}=http://${IP_2}:23800,${IP_3}=http://${IP_3}:23800 \
    --initial-cluster-token my-etcd-token \
    --initial-cluster-state new

[Install]
WantedBy=multi-user.target

5. sudo systemctl daemon-reload
6. sudo systemctl enable hpe-etcd-2.service
7. sudo systemctl start hpe-etcd-2.service

List members of etcd cluster

etcdctl --endpoint http://${IP_3}:23790 member list

92bf602c3e52c786: name=${IP_2} peerURLs=http://${IP_2}:23800 clientURLs=http://${IP_2}:23790 isLeader=true

df87d2bb2823677b: name=${IP_3} peerURLs=http://${IP_3}:23800 clientURLs=http://${IP_3}:23790 isLeader=false

eba454355c8689a7: name=${IP_1} peerURLs=http://${IP_1}:23800 clientURLs=http://${IP_1}:23790 isLeader=false

Command to check the health of etcd cluster:

etcdctl --endpoint http://${IP_3}:23790 cluster-health
member 69973f2749d2cb96 is healthy: got healthy result from http://${IP_3}:23790
member 92bf602c3e52c786 is healthy: got healthy result from http://${IP_2}:23790
member eba454355c8689a7 is healthy: got healthy result from http://${IP_1}:23790
cluster is healthy

Sample python program using etcd client.

import etcd
client = etcd.Client(host=(('${IP_2}',23790),('${IP_3}',23790),('${IP_1}',23790)),protocol='http',port=23790,allow_reconnect=True)
client.write('/nodes/n1',1)
print client.read('/nodes/n1')

Sample CURL call to one of the cluster member

curl http://${IP_3}:23790/v2/members
{"members":[{"id":"69973f2749d2cb96","name":"etcd3","peerURLs":["http://${IP_3}:23800"],"clientURLs":["http://${IP_3}:23790"]},{"id":"92bf602c3e52c786","name":"${IP_2}","peerURLs":["http://${IP_2}:23800"],"clientURLs":["http://${IP_2}:23790"]},{"id":"eba454355c8689a7","name":"${IP_1}","peerURLs":["http://${IP_1}:23800"],"clientURLs":["http://${IP_1}:23790"]}]}