Operator Tasks on etcd

How to Set Up a Demo etcd Cluster

Mon, 01 Jan 0001 00:00:00 +0000

On each etcd node, specify the cluster members:

TOKEN=token-01
CLUSTER_STATE=new
NAME_1=machine-1
NAME_2=machine-2
NAME_3=machine-3
HOST_1=10.240.0.17
HOST_2=10.240.0.18
HOST_3=10.240.0.19
CLUSTER=${NAME_1}=http://${HOST_1}:2380,${NAME_2}=http://${HOST_2}:2380,${NAME_3}=http://${HOST_3}:2380

Run this on each machine:

# For machine 1
THIS_NAME=${NAME_1}
THIS_IP=${HOST_1}
etcd --data-dir=data.etcd --name ${THIS_NAME} \
	--initial-advertise-peer-urls http://${THIS_IP}:2380 --listen-peer-urls http://${THIS_IP}:2380 \
	--advertise-client-urls http://${THIS_IP}:2379 --listen-client-urls http://${THIS_IP}:2379 \
	--initial-cluster ${CLUSTER} \
	--initial-cluster-state ${CLUSTER_STATE} --initial-cluster-token ${TOKEN}

# For machine 2
THIS_NAME=${NAME_2}
THIS_IP=${HOST_2}
etcd --data-dir=data.etcd --name ${THIS_NAME} \
	--initial-advertise-peer-urls http://${THIS_IP}:2380 --listen-peer-urls http://${THIS_IP}:2380 \
	--advertise-client-urls http://${THIS_IP}:2379 --listen-client-urls http://${THIS_IP}:2379 \
	--initial-cluster ${CLUSTER} \
	--initial-cluster-state ${CLUSTER_STATE} --initial-cluster-token ${TOKEN}

# For machine 3
THIS_NAME=${NAME_3}
THIS_IP=${HOST_3}
etcd --data-dir=data.etcd --name ${THIS_NAME} \
	--initial-advertise-peer-urls http://${THIS_IP}:2380 --listen-peer-urls http://${THIS_IP}:2380 \
	--advertise-client-urls http://${THIS_IP}:2379 --listen-client-urls http://${THIS_IP}:2379 \
	--initial-cluster ${CLUSTER} \
	--initial-cluster-state ${CLUSTER_STATE} --initial-cluster-token ${TOKEN}

Or use our public discovery service:

How to conduct leader election in etcd cluster

Mon, 01 Jan 0001 00:00:00 +0000

Prerequisites

Ensure etcd and etcdctl is installed.
Check for active etcd cluster.

Conduct Leader election

The etcdctl command is used to conduct leader elections in an etcd cluster. It makes sure that only one client can become leader at a time.

etcdctl --endpoints=$ENDPOINTS elect <election-name> [proposal]

etcdctl --endpoints=$ENDPOINTS elect election-name p1

Options

--endpoints : $ENDPOINTS

Address of each etcd cluster members.

election-name string

A string identifier for the election. All participants competing for leadership must use the same election name.

How to check Cluster status

Mon, 01 Jan 0001 00:00:00 +0000

Prerequisites

Install etcd and etcdctl

Check Overall Status

endpoint status to check the overall status of each endpoint specified in --endpoints flag:

etcdctl endpoint status (--endpoints=$ENDPOINTS|--cluster)

Options

--cluster[=false]: use all endpoints from the cluster member list

Check Health

endpoint health to check the healthiness of each endpoint specified in --endpoints flag:

etcdctl endpoint health (--endpoints=$ENDPOINTS|--cluster)

Options

--cluster[=false]: use all endpoints from the cluster member list

Check KV Hash

endpoint hashkv to check the KV history hash of each endpoint specified in --endpoints flag:

How to save the database

Mon, 01 Jan 0001 00:00:00 +0000

Pre-requisites

Snapshot a database

snapshot to save point-in-time snapshot of etcd database:

etcdctl --endpoints=$ENDPOINT snapshot save DB_NAME

Global Options

etcdctl

--endpoints=[127.0.0.1:2379], gRPC endpoints

Snapshot can only be requested from one etcd node, so --endpoints flag should contain only one endpoint.

etcdutl

-w, --write-out string   set the output format (fields, json, protobuf, simple, table) (default "simple")

Example

ENDPOINTS=$HOST_1:2379
etcdctl --endpoints=$ENDPOINTS snapshot save my.db

Snapshot saved at my.db

etcdutl --write-out=table snapshot status my.db

+---------+----------+------------+------------+
|  HASH   | REVISION | TOTAL KEYS | TOTAL SIZE |
+---------+----------+------------+------------+
| c55e8b8 |        9 |         13 | 25 kB      |
+---------+----------+------------+------------+

How to Add and Remove Members

Mon, 01 Jan 0001 00:00:00 +0000

member to add,remove,update membership:

# For each machine
TOKEN=my-etcd-token-1
CLUSTER_STATE=new
NAME_1=etcd-node-1
NAME_2=etcd-node-2
NAME_3=etcd-node-3
HOST_1=10.240.0.13
HOST_2=10.240.0.14
HOST_3=10.240.0.15
CLUSTER=${NAME_1}=http://${HOST_1}:2380,${NAME_2}=http://${HOST_2}:2380,${NAME_3}=http://${HOST_3}:2380

# For node 1
THIS_NAME=${NAME_1}
THIS_IP=${HOST_1}
etcd --data-dir=data.etcd --name ${THIS_NAME} \
	--initial-advertise-peer-urls http://${THIS_IP}:2380 \
	--listen-peer-urls http://${THIS_IP}:2380 \
	--advertise-client-urls http://${THIS_IP}:2379 \
	--listen-client-urls http://${THIS_IP}:2379 \
	--initial-cluster ${CLUSTER} \
	--initial-cluster-state ${CLUSTER_STATE} \
	--initial-cluster-token ${TOKEN}

# For node 2
THIS_NAME=${NAME_2}
THIS_IP=${HOST_2}
etcd --data-dir=data.etcd --name ${THIS_NAME} \
	--initial-advertise-peer-urls http://${THIS_IP}:2380 \
	--listen-peer-urls http://${THIS_IP}:2380 \
	--advertise-client-urls http://${THIS_IP}:2379 \
	--listen-client-urls http://${THIS_IP}:2379 \
	--initial-cluster ${CLUSTER} \
	--initial-cluster-state ${CLUSTER_STATE} \
	--initial-cluster-token ${TOKEN}

# For node 3
THIS_NAME=${NAME_3}
THIS_IP=${HOST_3}
etcd --data-dir=data.etcd --name ${THIS_NAME} \
	--initial-advertise-peer-urls http://${THIS_IP}:2380 \
	--listen-peer-urls http://${THIS_IP}:2380 \
	--advertise-client-urls http://${THIS_IP}:2379 \
	--listen-client-urls http://${THIS_IP}:2379 \
	--initial-cluster ${CLUSTER} \
	--initial-cluster-state ${CLUSTER_STATE} \
	--initial-cluster-token ${TOKEN}

Then replace a member with member remove and member add commands: