etcd

https://etcd.io/docs/v3.7/
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### Example: put keys and get by prefix

Source: https://etcd.io/docs/v3.7/tasks/developer/how-to-get-key-by-prefix/

This example first puts three keys (web1, web2, web3) with values, then retrieves all keys with the prefix 'web' using the --prefix flag. The output will list the keys and their values.

```shell
etcdctl --endpoints=$ENDPOINTS put web1 value1
etcdctl --endpoints=$ENDPOINTS put web2 value2
etcdctl --endpoints=$ENDPOINTS put web3 value3

etcdctl --endpoints=$ENDPOINTS get web --prefix
```

--------------------------------

### etcdctl watch examples

Source: https://etcd.io/docs/v3.7/tasks/developer/how-to-watch-keys/

Examples of watching a single key and watching keys with a prefix. The first example watches 'stock1' and then puts a value to trigger a notification. The second example watches all keys with prefix 'stock' and puts values to trigger notifications.

```shell
etcdctl --endpoints=$ENDPOINTS watch stock1
etcdctl --endpoints=$ENDPOINTS put stock1 1000

etcdctl --endpoints=$ENDPOINTS watch stock --prefix
etcdctl --endpoints=$ENDPOINTS put stock1 10
etcdctl --endpoints=$ENDPOINTS put stock2 20
```

--------------------------------

### Install etcd-dump-logs tool

Source: https://etcd.io/docs/v3.7/learning/persistent-storage-files/

Installs the etcd-dump-logs tool using go install. The tool is used to read etcd WAL logs.

```shell
% go install go.etcd.io/etcd/v3/tools/etcd-dump-logs@latest
```

--------------------------------

### Start etcd with client certificate authentication

Source: https://etcd.io/docs/v3.7/op-guide/security/

Starts etcd with client certificate authentication enabled, requiring clients to present a certificate signed by the trusted CA. Uses the same server files as the first example plus a client key pair.

```sh
$ etcd --name infra0 --data-dir infra0 \
  --client-cert-auth --trusted-ca-file=/path/to/ca.crt --cert-file=/path/to/server.crt --key-file=/path/to/server.key \
  --advertise-client-urls https://127.0.0.1:2379 --listen-client-urls https://127.0.0.1:2379
```

--------------------------------

### Install Prometheus

Source: https://etcd.io/docs/v3.7/op-guide/monitoring/

Downloads and installs Prometheus version 2.0.0, extracts it to /tmp, and verifies the installation.

```sh
PROMETHEUS_VERSION="2.0.0"
wget https://github.com/prometheus/prometheus/releases/download/v$PROMETHEUS_VERSION/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz -O /tmp/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz
tar -xvzf /tmp/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz --directory /tmp/ --strip-components=1
/tmp/prometheus -version
```

--------------------------------

### Start etcd on infra2 with static bootstrap

Source: https://etcd.io/docs/v3.7/op-guide/clustering/

Starts etcd on the third member (infra2) with static bootstrap. Uses the same initial-cluster-token as the other members. The --initial-cluster flags are ignored on subsequent runs.

```bash
$ etcd --name infra2 --initial-advertise-peer-urls http://10.0.1.12:2380 \
  --listen-peer-urls http://10.0.1.12:2380 \
  --listen-client-urls http://10.0.1.12:2379,http://127.0.0.1:2379 \
  --advertise-client-urls http://10.0.1.12:2379 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-cluster infra0=http://10.0.1.10:2380,infra1=http://10.0.1.11:2380,infra2=http://10.0.1.12:2380 \
  --initial-cluster-state new
```

--------------------------------

### Example: endpoint hashkv with table output

Source: https://etcd.io/docs/v3.7/tasks/operator/how-to-check-cluster-status/

Example command to check KV hash with table output, followed by the resulting table showing endpoint hashes and hash revisions.

```shell
etcdctl --cluster endpoint hashkv  --write-out=table

+------------------+------------+---------------+
|     ENDPOINT     |    HASH    | HASH REVISION |
+------------------+------------+---------------+
| 10.240.0.17:2379 | 3892279174 |             3 |
| 10.240.0.18:2379 | 3892279174 |             3 |
| 10.240.0.19:2379 | 3892279174 |             3 |
+------------------+------------+---------------+
```

--------------------------------

### Start a standalone etcd cluster

Source: https://etcd.io/docs/v3.7/dev-guide/local_cluster/

Run the etcd binary to start a standalone cluster. If the binary is not in the current directory, it may be at $GOPATH/bin/etcd or /usr/local/bin/etcd. The member listens on localhost:2379 for client requests.

```bash
$ ./etcd
...
```

--------------------------------

### Start etcd on infra1 with static bootstrap

Source: https://etcd.io/docs/v3.7/op-guide/clustering/

Starts etcd on the second member (infra1) with static bootstrap. Uses the same initial-cluster-token as infra0. The --initial-cluster flags are ignored on subsequent runs.

```bash
$ etcd --name infra1 --initial-advertise-peer-urls http://10.0.1.11:2380 \
  --listen-peer-urls http://10.0.1.11:2380 \
  --listen-client-urls http://10.0.1.11:2379,http://127.0.0.1:2379 \
  --advertise-client-urls http://10.0.1.11:2379 \
  --initial-cluster-token etcd-cluster-1 \
  --initial-cluster infra0=http://10.0.1.10:2380,infra1=http://10.0.1.11:2380,infra2=http://10.0.1.12:2380 \
  --initial-cluster-state new
```

--------------------------------

### Example: endpoint health with output

Source: https://etcd.io/docs/v3.7/tasks/operator/how-to-check-cluster-status/

Example command to check endpoint health, followed by the output showing each endpoint is healthy with commit times.

```shell
etcdctl --endpoints=$ENDPOINTS endpoint health

10.240.0.17:2379 is healthy: successfully committed proposal: took = 3.345431ms
10.240.0.19:2379 is healthy: successfully committed proposal: took = 3.767967ms
10.240.0.18:2379 is healthy: successfully committed proposal: took = 4.025451ms
```

--------------------------------

### Start etcd gateway with static endpoints

Source: https://etcd.io/docs/v3.7/op-guide/gateway/

Starts the etcd gateway using the --endpoints flag with a comma-separated list of static endpoints. The output shows the gateway ready to proxy client requests.

```bash
$ etcd gateway start --endpoints=infra0.example.com:2379,infra1.example.com:2379,infra2.example.com:2379
2016-08-16 11:21:18.867350 I | tcpproxy: ready to proxy client requests to [...]
```

--------------------------------

### Install goreman

Source: https://etcd.io/docs/v3.7/dev-guide/local_cluster/

Install goreman to control Procfile-based applications, required for starting a multi-member cluster.

```bash
$ go install github.com/mattn/goreman@latest
```

--------------------------------

### Start etcd cluster with client HTTPS

Source: https://etcd.io/docs/v3.7/op-guide/grpc_proxy/

Starts a single-member etcd cluster with client HTTPS enabled, using the provided certificate and key files. This is the secure backend for the TLS termination example.

```sh
$ etcd --listen-client-urls https://localhost:2379 --advertise-client-urls https://localhost:2379 --cert-file=peer.crt --key-file=peer.key --trusted-ca-file=ca.crt --client-cert-auth
```

--------------------------------

### clientv3.NewFromConfigFile before move

Source: https://etcd.io/docs/v3.7/upgrades/upgrade_3_2/

Shows the old way to load configuration from a file using clientv3.NewFromConfigFile.

```go
import "github.com/coreos/etcd/clientv3"
clientv3.NewFromConfigFile
```

--------------------------------

### Go: SetupLogging with embed.Config

Source: https://etcd.io/docs/v3.7/upgrades/upgrade_3_3/

Shows how to set up logging using embed.Config.SetupLogging. Note that this method has been deprecated in v3.4. Set embed.Config.Debug to true to enable gRPC server logs.

```go
import "github.com/coreos/etcd/embed"

cfg := &embed.Config{Debug: false}
cfg.SetupLogging()
```

--------------------------------

### Set up initial data with etcdctl put

Source: https://etcd.io/docs/v3.7/tasks/developer/how-to-transactional-write/

Creates initial data for a user by putting email and phone keys.

```shell
etcdctl put /users/12345/email "old.address@johndoe.com"
etcdctl put /users/12345/phone "123-456-7890"
```

--------------------------------

### Put and get keys with gRPC gateway

Source: https://etcd.io/docs/v3.7/dev-guide/api_grpc_gateway/

Use /v3/kv/put and /v3/kv/range to write and read keys. Keys and values must be base64 encoded. The example includes a comment showing that 'foo' is 'Zm9v' and 'bar' is 'YmFy' in Base64, and demonstrates a range query with range_end to get all keys prefixed with 'foo'.

```bash
<<COMMENT
https://www.base64encode.org/
foo is 'Zm9v' in Base64
bar is 'YmFy'
COMMENT

curl -L http://localhost:2379/v3/kv/put \
  -X POST -d '{"key": "Zm9v", "value": "YmFy"}'
# {"header":{"cluster_id":"12585971608760269493","member_id":"13847567121247652255","revision":"2","raft_term":"3"}}

curl -L http://localhost:2379/v3/kv/range \
  -X POST -d '{"key": "Zm9v"}'
# {"header":{"cluster_id":"12585971608760269493","member_id":"13847567121247652255","revision":"2","raft_term":"3"},"kvs":[{"key":"Zm9v","create_revision":"2","mod_revision":"2","version":"1","value":"YmFy"}],"count":"1"}

# get all keys prefixed with "foo"
curl -L http://localhost:2379/v3/kv/range \
  -X POST -d '{"key": "Zm9v", "range_end": "Zm9w"}'
# {"header":{"cluster_id":"12585971608760269493","member_id":"13847567121247652255","revision":"2","raft_term":"3"},"kvs":[{"key":"Zm9v","create_revision":"2","mod_revision":"2","version":"1","value":"YmFy"}],"count":"1"}
```

--------------------------------

### etcd startup with --peer-cert-allowed-cn etcd.local and success output

Source: https://etcd.io/docs/v3.7/op-guide/security/

Command to start etcd with --peer-cert-allowed-cn etcd.local, showing successful cluster startup and serving client requests.

```bash
etcd --peer-cert-allowed-cn etcd.local

I | pkg/netutil: resolving m3.etcd.local:32380 to 127.0.0.1:32380
I | pkg/netutil: resolving m2.etcd.local:22380 to 127.0.0.1:22380
I | pkg/netutil: resolving m1.etcd.local:2380 to 127.0.0.1:2380
I | etcdserver: published {Name:m3 ClientURLs:[https://m3.etcd.local:32379]} to cluster 9db03f09b20de32b
I | embed: ready to serve client requests
I | etcdserver: published {Name:m1 ClientURLs:[https://m1.etcd.local:2379]} to cluster 9db03f09b20de32b
I | embed: ready to serve client requests
I | etcdserver: published {Name:m2 ClientURLs:[https://m2.etcd.local:22379]} to cluster 9db03f09b20de32b
I | embed: ready to serve client requests
I | embed: serving client requests on 127.0.0.1:32379
I | embed: serving client requests on 127.0.0.1:22379
I | embed: serving client requests on 127.0.0.1:2379
```

--------------------------------

### Set up authentication with /v3/auth service

Source: https://etcd.io/docs/v3.7/dev-guide/api_grpc_gateway/

Creates a root user, root role, grants the role, and enables auth. Each command returns a JSON header with cluster_id, member_id, revision, and raft_term.

```bash
curl -L http://localhost:2379/v3/auth/user/add \
  -X POST -d '{"name": "root", "password": "pass"}'
# {"header":{"cluster_id":"14841639068965178418","member_id":"10276657743932975437","revision":"1","raft_term":"2"}}
```

```bash
curl -L http://localhost:2379/v3/auth/role/add \
  -X POST -d '{"name": "root"}'
# {"header":{"cluster_id":"14841639068965178418","member_id":"10276657743932975437","revision":"1","raft_term":"2"}}
```

```bash
curl -L http://localhost:2379/v3/auth/user/grant \
  -X POST -d '{"user": "root", "role": "root"}'
# {"header":{"cluster_id":"14841639068965178418","member_id":"10276657743932975437","revision":"1","raft_term":"2"}}
```

```bash
curl -L http://localhost:2379/v3/auth/enable -X POST -d '{}'
# {"header":{"cluster_id":"14841639068965178418","member_id":"10276657743932975437","revision":"1","raft_term":"2"}}
```

--------------------------------

### etcdctl get --prefix foo - range over all keys prefixed with foo

Source: https://etcd.io/docs/v3.7/dev-guide/interacting_v3/

Ranges over all keys prefixed with 'foo'. The output includes all keys starting with 'foo' and their values.

```bash
$ etcdctl get --prefix foo
foo
bar
foo1
bar1
foo2
bar2
foo3
bar3

```

--------------------------------

### Sample keys with revisions for reading past versions

Source: https://etcd.io/docs/v3.7/dev-guide/interacting_v3/

Shows the key-value pairs and their corresponding revisions used in the examples for reading past versions of keys.

```bash
foo = bar         # revision = 2
foo1 = bar1       # revision = 3
foo = bar_new     # revision = 4
foo1 = bar1_new   # revision = 5
```

--------------------------------

### Get keys by prefix with etcdctl

Source: https://etcd.io/docs/v3.7/tasks/developer/how-to-get-key-by-prefix/

Use this command to retrieve all keys that start with the given PREFIX. The --prefix flag enables range queries for keys with a matching prefix. Replace $ENDPOINTS with your etcd endpoint addresses.

```bash
$ etcdctl --endpoints=$ENDPOINTS get PREFIX --prefix
```

--------------------------------

### clientv3.yaml.NewConfig after move

Source: https://etcd.io/docs/v3.7/upgrades/upgrade_3_2/

Shows the new way to load configuration from a file using clientv3yaml.NewConfig.

```go
import clientv3yaml "github.com/coreos/etcd/clientv3/yaml"
clientv3yaml.NewConfig
```

--------------------------------

### Watch keys with gRPC gateway

Source: https://etcd.io/docs/v3.7/dev-guide/api_grpc_gateway/

Use /v3/watch to watch keys. The example starts a watch request in the background, then performs a put to trigger an event. The watch response includes the created watch and the event with the key-value pair.

```bash
curl -N http://localhost:2379/v3/watch \
  -X POST -d '{"create_request": {"key":"Zm9v"} }' &
# {"result":{"header":{"cluster_id":"12585971608760269493","member_id":"13847567121247652255","revision":"1","raft_term":"2"},"created":true}}

curl -L http://localhost:2379/v3/kv/put \
  -X POST -d '{"key": "Zm9v", "value": "YmFy"}' >/dev/null 2>&1
# {"result":{"header":{"cluster_id":"12585971608760269493","member_id":"13847567121247652255","revision":"2","raft_term":"2"},"events":[{"kv":{"key":"Zm9v","create_revision":"2","mod_revision":"2","version":"1","value":"YmFy"}}]}}
```

--------------------------------

### Initialize etcd gRPC resolver with client

Source: https://etcd.io/docs/v3.7/dev-guide/grpc_naming/

Shows how to create an etcd client and use it to build a gRPC resolver for service discovery. The resolver is passed to grpc.NewClient with the service name.

```go
import (
	clientv3 "go.etcd.io/etcd/client/v3"
	etcdnaming "go.etcd.io/etcd/client/v3/naming/resolver"

	"google.golang.org/grpc"
)

...

cli, err := clientv3.NewFromURL("http://localhost:2379")
if err != nil {
    // ...
}
r, err := etcdnaming.NewBuilder(cli)
if err != nil {
    // ...
}
conn, gerr := grpc.NewClient("my-service", grpc.WithResolvers(r), ...)
```

--------------------------------

### etcdctl watch options

Source: https://etcd.io/docs/v3.7/tasks/developer/how-to-watch-keys/

Options for the watch command: -i for interactive mode, --prefix to watch on a prefix, --rev to set revision to start watching, --prev-kv to get previous key-value pair, --progress-notify for periodic progress notifications.

```bash
-i, --interactive[=false]: interactive mode
--prefix[=false]: watch on a prefix if prefix is set
--rev=0: Revision to start watching
--prev-kv[=false]: get the previous key-value pair before the event happens
--progress-notify[=false]: get periodic watch progress notification from server
```

--------------------------------

### Write benchmark commands

Source: https://etcd.io/docs/v3.7/op-guide/performance/

Sample commands for benchmarking write performance. Includes commands to write to the leader with 1 connection/client and 100 connections/1000 clients, and to write to all members with 100 connections/1000 clients.

```sh
# write to leader
benchmark --endpoints=${HOST_1} --target-leader --conns=1 --clients=1 \
    put --key-size=8 --sequential-keys --total=10000 --val-size=256
benchmark --endpoints=${HOST_1} --target-leader  --conns=100 --clients=1000 \
    put --key-size=8 --sequential-keys --total=100000 --val-size=256

# write to all members
benchmark --endpoints=${HOST_1},${HOST_2},${HOST_3} --conns=100 --clients=1000 \
    put --key-size=8 --sequential-keys --total=100000 --val-size=256
```

--------------------------------

### Start Prometheus with etcd configuration

Source: https://etcd.io/docs/v3.7/op-guide/monitoring/

Launches Prometheus in the background using the created configuration file, listening on port 9090, and logging output to /tmp/test-etcd.log.

```sh
nohup /tmp/prometheus \
    -config.file /tmp/test-etcd.yaml \
    -web.listen-address ":9090" \
    -storage.local.path "test-etcd.data" >> /tmp/test-etcd.log  2>&1 &
```

--------------------------------

### Get current revision with etcdctl get -w=json

Source: https://etcd.io/docs/v3.7/dev-guide/interacting_v3/

Retrieve the current revision of the etcd server by getting any key (existent or non-existent) in JSON format. The response header includes the revision.

```bash
$ etcdctl get mykey -w=json
{"header":{"cluster_id":14841639068965178418,"member_id":10276657743932975437,"revision":15,"raft_term":4}}
```

--------------------------------

### Install etcd via Homebrew on macOS

Source: https://etcd.io/docs/v3.7/install/

Installs etcd using Homebrew on macOS.

```sh
$ brew install etcd
```

--------------------------------

### Set up initial three-node etcd cluster

Source: https://etcd.io/docs/v3.7/tasks/operator/how-to-deal-with-membership/

Defines environment variables for a three-node etcd cluster and starts each node with the 'new' cluster state. Use this to bootstrap a fresh cluster.

```shell
# 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}
```

--------------------------------

### Get role permissions with etcdctl role get

Source: https://etcd.io/docs/v3.7/op-guide/authentication/rbac/

Displays the permissions granted to a specific role.

```shell
$ etcdctl role get myrolename

```

--------------------------------

### etcdctl elect example with output

Source: https://etcd.io/docs/v3.7/tasks/operator/how-to-conduct-elections/

Example of running etcdctl elect with an election name and proposal, showing the output including the election key and proposal value. Also shows a second election with a different name.

```shell
./etcdctl elect my-election proposal1
my-election/694d99fafea88404
proposal1

another election:
./etcdctl elect new-election proposal1
new-election/694d99fafea8840f
proposal1
```

--------------------------------

### Bootstrap etcd cluster with DNS SRV using IP addresses

Source: https://etcd.io/docs/v3.7/op-guide/clustering/

Start three etcd members (infra0, infra1, infra2) using --discovery-srv example.com and IP addresses in --initial-advertise-peer-urls. The resolved address must match one of the SRV targets.

```shell
$ etcd --name infra0 \
--discovery-srv example.com \
--initial-advertise-peer-urls http://10.0.1.10:2380 \
--initial-cluster-token etcd-cluster-1 \
--initial-cluster-state new \
--advertise-client-urls http://10.0.1.10:2379 \
--listen-client-urls http://10.0.1.10:2379 \
--listen-peer-urls http://10.0.1.10:2380
```

```shell
$ etcd --name infra1 \
--discovery-srv example.com \
--initial-advertise-peer-urls http://10.0.1.11:2380 \
--initial-cluster-token etcd-cluster-1 \
--initial-cluster-state new \
--advertise-client-urls http://10.0.1.11:2379 \
--listen-client-urls http://10.0.1.11:2379 \
--listen-peer-urls http://10.0.1.11:2380
```

```shell
$ etcd --name infra2 \
--discovery-srv example.com \
--initial-advertise-peer-urls http://10.0.1.12:2380 \
--initial-cluster-token etcd-cluster-1 \
--initial-cluster-state new \
--advertise-client-urls http://10.0.1.12:2379 \
--listen-client-urls http://10.0.1.12:2379 \
--listen-peer-urls http://10.0.1.12:2380
```

--------------------------------

### Options for etcdctl get --prefix

Source: https://etcd.io/docs/v3.7/tasks/developer/how-to-get-key-by-prefix/

The --prefix option enables getting a range of keys that match the given prefix.

```bash
--prefix, get a range of keys with matching prefix
```

--------------------------------

### Bootstrap etcd cluster with DNS SRV using domain names

Source: https://etcd.io/docs/v3.7/op-guide/clustering/

Start three etcd members (infra0, infra1, infra2) using --discovery-srv example.com and domain names in --initial-advertise-peer-urls. The resolved address must match one of the SRV targets. Since 3.2, --listen-peer-urls and --listen-client-urls reject domain names for binding.

```shell
$ etcd --name infra0 \
--discovery-srv example.com \
--initial-advertise-peer-urls http://infra0.example.com:2380 \
--initial-cluster-token etcd-cluster-1 \
--initial-cluster-state new \
--advertise-client-urls http://infra0.example.com:2379 \
--listen-client-urls http://0.0.0.0:2379 \
--listen-peer-urls http://0.0.0.0:2380
```

```shell
$ etcd --name infra1 \
--discovery-srv example.com \
--initial-advertise-peer-urls http://infra1.example.com:2380 \
--initial-cluster-token etcd-cluster-1 \
--initial-cluster-state new \
--advertise-client-urls http://infra1.example.com:2379 \
--listen-client-urls http://0.0.0.0:2379 \
--listen-peer-urls http://0.0.0.0:2380
```

```shell
$ etcd --name infra2 \
--discovery-srv example.com \
--initial-advertise-peer-urls http://infra2.example.com:2380 \
--initial-cluster-token etcd-cluster-1 \
--initial-cluster-state new \
--advertise-client-urls http://infra2.example.com:2379 \
--listen-client-urls http://0.0.0.0:2379 \
--listen-peer-urls http://0.0.0.0:2380
```

--------------------------------

### Retrieve a key with etcdctl get

Source: https://etcd.io/docs/v3.7/dev-guide/local_cluster/

Use etcdctl get to retrieve the value of a key. If the expected value is returned, interaction with the cluster is working.

```bash
$ ./etcdctl get foo
bar
```

--------------------------------

### Install cert-manager with Helm

Source: https://etcd.io/docs/v3.7/op-guide/kubernetes/

Use this Helm command to install cert-manager into the cert-manager namespace with CRDs enabled. This is a prerequisite for generating self-signed certificates in the cluster.

```shell
$ helm upgrade --install --create-namespace --namespace cert-manager cert-manager cert-manager --repo https://charts.jetstack.io --set crds.enabled=true
```

--------------------------------

### Get lease TTL information

Source: https://etcd.io/docs/v3.7/dev-guide/interacting_v3/

Command to get the remaining TTL of a lease. The output shows the lease ID, granted TTL, and remaining time.

```bash
$ etcdctl lease timetolive 694d5765fc71500b
lease 694d5765fc71500b granted with TTL(500s), remaining(258s)
```
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