[쿠버네티스 kubernetes] etcdctl command 가이드

출처: https://velog.io/@wanny328/kubernetes-etcdctl-command-%EA%B0%80%EC%9D%B4%EB%93%9C

 

etcd란?

etcd는 kuberntes의 cluster 정보를 key-value 형식으로 저장하는 DB로 kubernetes cluster 운영에 있어 매우 중요.

 

1. 버전 체크

$ etcdctl version

## 출력 예시
etcdctl version: 3.4.13
API version: 3.4

 

2. etcd 맴버 조회

$ etcdctl member list  -w=table

-w=table 옵션을 주면 가독성 좋게 출력됩니다.

## 출력 예시
+------------------+---------+-------------+------------------------------+------------------------------+------------+
|        ID        | STATUS  |    NAME     |          PEER ADDRS          |         CLIENT ADDRS         | IS LEARNER |
+------------------+---------+-------------+------------------------------+------------------------------+------------+
| 85792d9beda616ff | started | k8s-master2 | https://192.168.178.166:2380 | https://192.168.178.166:2379 |      false |
| 90046ab4d4049c30 | started | k8s-master3 | https://192.168.178.167:2380 | https://192.168.178.167:2379 |      false |
| e5a6eae61bf0e6a6 | started | k8s-master1 | https://192.168.178.165:2380 | https://192.168.178.165:2379 |      false |
+------------------+---------+-------------+------------------------------+------------------------------+------------+

 

3. health check

$ etcdctl endpoint health --cluster -w=table

## 출력 예시

+------------------------------+--------+------------+-------+
|           ENDPOINT           | HEALTH |    TOOK    | ERROR |
+------------------------------+--------+------------+-------+
| https://192.168.178.165:2379 |   true | 8.721097ms |       |
| https://192.168.178.166:2379 |   true |  9.55216ms |       |
| https://192.168.178.167:2379 |   true | 9.634818ms |       |
+------------------------------+--------+------------+-------+

 

4. etcd 리더 및 전체 상태 조회

$ etcdctl endpoint status --cluster -w=table

## 출력 예시
+------------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
|           ENDPOINT           |        ID        | VERSION | DB SIZE | IS LEADER | IS LEARNER | RAFT TERM | RAFT INDEX | RAFT APPLIED INDEX | ERRORS |
+------------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
| https://192.168.178.166:2379 | 85792d9beda616ff |   3.4.3 |  9.7 MB |     false |      false |        21 |     325815 |             325815 |        |
| https://192.168.178.167:2379 | 90046ab4d4049c30 |   3.4.3 |  9.7 MB |     false |      false |        21 |     325815 |             325815 |        |
| https://192.168.178.165:2379 | e5a6eae61bf0e6a6 |   3.4.3 |  9.7 MB |      true |      false |        21 |     325815 |             325815 |        |
+------------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+

 

5. etcd 백업

$ etcdctl snapshot save { 백업할 경로 }/etcd-`date +%Y%m%d_%H%M%S`

etcd-'date~' 은 생성될 snapshot 파일명으로 꼭 저 값이 아니라 원하는 값으로 변경해서 사용해도 괜찮습니다.

## 출력 예시

{"level":"info","ts":1688107398.147482,"caller":"snapshot/v3_snapshot.go:119","msg":"created temporary db file","path":"/root/etcd/etcd-20230630_154318.part"}
{"level":"info","ts":"2023-06-30T15:43:18.154+0900","caller":"clientv3/maintenance.go:200","msg":"opened snapshot stream; downloading"}
{"level":"info","ts":1688107398.154079,"caller":"snapshot/v3_snapshot.go:127","msg":"fetching snapshot","endpoint":"https://192.168.178.165:2379"}
{"level":"info","ts":"2023-06-30T15:43:18.221+0900","caller":"clientv3/maintenance.go:208","msg":"completed snapshot read; closing"}
{"level":"info","ts":1688107398.3090427,"caller":"snapshot/v3_snapshot.go:142","msg":"fetched snapshot","endpoint":"https://192.168.178.165:2379","size":"9.7 MB","took":0.16142193}
{"level":"info","ts":1688107398.3091292,"caller":"snapshot/v3_snapshot.go:152","msg":"saved","path":"/root/etcd/etcd-20230630_154318"}
Snapshot saved at /root/etcd/etcd-20230630_154318

 

6. etcd 복구

etcdctl snapshot restore { etcd snapshot 파일} \
--name { command 수행하는 node hostname } \
--data-dir /var/lib/etcd/recover \
--initial-cluster { master1 hostname }=https://{ master1 IP }:2380,{ master2 hostname }=https://{ master2 IP }:2380,{ master3 hostname }=https://{ master3 IP }:2380 \
--initial-advertise-peer-urls https://{ command 수행하는 노드 IP }:2380

 

 

ETCDCTL is the CLI tool used to interact with ETCD.

ETCDCTL can interact with ETCD Server using 2 API versions - Version 2 and Version 3.  By default its set to use Version 2. Each version has different sets of commands.

For example ETCDCTL version 2 supports the following commands:

1. etcdctl backup
2. etcdctl cluster-health
3. etcdctl mk
4. etcdctl mkdir
5. etcdctl set

 

Whereas the commands are different in version 3

1. etcdctl snapshot save
2. etcdctl endpoint health
3. etcdctl get
4. etcdctl put