교육, 커뮤니티 후기/DOIK (데이터베이스 오퍼레이터 인 쿠버네티스) 스터디

DOIK 1주차 - 도전과제1(Deploying Cassandra with a StatefulSet) + 도전과제4(kui)

Somaz 2023. 10. 19. 00:48
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Overview

 

1주차 도전 과제는 `Deploying Cassandra with a StatefulSet` 과  `kui 설치` 를 진행해 보았다.

출처 : https://www.educba.com/what-is-cassandra/

 

Cassandra란?

Apache Cassandra는 많은 상용 서버에서 매우 많은 양의 구조화된 데이터를 관리하도록 설계된 무료 오픈 소스 분산 NoSQL 데이터베이스 시스템으로, 단일 장애 지점 없이 고가용성을 제공한다.

​

Deploying Cassandra with a StatefulSet

Kubernetes에서 Apache Cassandra를 배포해보려고 한다. 데이터베이스인 Cassandra는 데이터 내구성을 제공하기 위해 영구 스토리지가 필요하다. 그리고 Cassandra seed provider를 사용하면 데이터베이스가 Cassandra 클러스터에 조인할 때 새 Cassandra 인스턴스를 검색할 수 있다.

 

 

 

Cassandra용 헤드리스 서비스 만들기

# cassandra-service.yaml
apiVersion: v1
kind: Service
metadata:
  labels:
    app: cassandra
  name: cassandra
spec:
  clusterIP: None
  ports:
  - port: 9042
  selector:
    app: cassandra

# cassandra-service.yaml 배포
kubectl apply -f https://k8s.io/examples/application/cassandra/cassandra-service.yaml

# cassandra-service 확인
k get svc cassandra
NAME        TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE
cassandra   ClusterIP   None         <none>        9042/TCP   100s

 

Statefulset을 사용하여 Cassandra ring 생성

스토리지 클래스만 수정해준다.

# StorageClass 확인
k get sc
NAME            PROVISIONER              RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
gp2 (default)   kubernetes.io/aws-ebs    Delete          WaitForFirstConsumer   false                  23m
gp3 (default)   ebs.csi.aws.com          Delete          WaitForFirstConsumer   true                   10m

# cassandra-statefulset.yaml
cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: cassandra
  labels:
    app: cassandra
spec:
  serviceName: cassandra
  replicas: 3
  selector:
    matchLabels:
      app: cassandra
  template:
    metadata:
      labels:
        app: cassandra
    spec:
      terminationGracePeriodSeconds: 1800
      containers:
      - name: cassandra
        image: gcr.io/google-samples/cassandra:v13
        imagePullPolicy: Always
        ports:
        - containerPort: 7000
          name: intra-node
        - containerPort: 7001
          name: tls-intra-node
        - containerPort: 7199
          name: jmx
        - containerPort: 9042
          name: cql
        resources:
          limits:
            cpu: "500m"
            memory: 1Gi
          requests:
            cpu: "500m"
            memory: 1Gi
        securityContext:
          capabilities:
            add:
              - IPC_LOCK
        lifecycle:
          preStop:
            exec:
              command: 
              - /bin/sh
              - -c
              - nodetool drain
        env:
          - name: MAX_HEAP_SIZE
            value: 512M
          - name: HEAP_NEWSIZE
            value: 100M
          - name: CASSANDRA_SEEDS
            value: "cassandra-0.cassandra.default.svc.cluster.local"
          - name: CASSANDRA_CLUSTER_NAME
            value: "K8Demo"
          - name: CASSANDRA_DC
            value: "DC1-K8Demo"
          - name: CASSANDRA_RACK
            value: "Rack1-K8Demo"
          - name: POD_IP
            valueFrom:
              fieldRef:
                fieldPath: status.podIP
        readinessProbe:
          exec:
            command:
            - /bin/bash
            - -c
            - /ready-probe.sh
          initialDelaySeconds: 15
          timeoutSeconds: 5
        # These volume mounts are persistent. They are like inline claims,
        # but not exactly because the names need to match exactly one of
        # the stateful pod volumes.
        volumeMounts:
        - name: cassandra-data
          mountPath: /cassandra_data
  # These are converted to volume claims by the controller
  # and mounted at the paths mentioned above.
  # do not use these in production until ssd GCEPersistentDisk or other ssd pd
  volumeClaimTemplates:
  - metadata:
      name: cassandra-data
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: gp3
      resources:
        requests:
          storage: 1Gi
EOF

 

Cassandra Statefulset 검증

k get po,svc,pv,pvc
NAME              READY   STATUS    RESTARTS   AGE
pod/cassandra-0   1/1     Running   0          4m14s
pod/cassandra-1   1/1     Running   0          3m11s
pod/cassandra-2   1/1     Running   0          93s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE
service/cassandra    ClusterIP   None         <none>        9042/TCP   15m
service/kubernetes   ClusterIP   10.100.0.1   <none>        443/TCP    34m

NAME                                                        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                                STORAGECLASS   REASON   AGE
persistentvolume/pvc-5710a239-c95f-4953-8c13-94c006b6a322   1Gi        RWO            Delete           Bound    default/cassandra-data-cassandra-2   gp3                     90s
persistentvolume/pvc-61a1467d-4bed-4ad3-bac5-f17685891a92   1Gi        RWO            Delete           Bound    default/cassandra-data-cassandra-1   gp3                     3m7s
persistentvolume/pvc-be749cd9-20cd-4214-b5d6-c10906c30bfd   1Gi        RWO            Delete           Bound    default/cassandra-data-cassandra-0   gp3                     4m11s

NAME                                               STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/cassandra-data-cassandra-0   Bound    pvc-be749cd9-20cd-4214-b5d6-c10906c30bfd   1Gi        RWO            gp3            4m14s
persistentvolumeclaim/cassandra-data-cassandra-1   Bound    pvc-61a1467d-4bed-4ad3-bac5-f17685891a92   1Gi        RWO            gp3            3m11s
persistentvolumeclaim/cassandra-data-cassandra-2   Bound    pvc-5710a239-c95f-4953-8c13-94c006b6a322   1Gi        RWO            gp3            93s

 

Cassandra Statefulset 수정

  • replica 3 → 4
kubectl edit statefulset cassandra
...
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: apps/v1
kind: StatefulSet
metadata:
  creationTimestamp: 2016-08-13T18:40:58Z
  generation: 1
  labels:
  app: cassandra
  name: cassandra
  namespace: default
  resourceVersion: "323"
  uid: 7a219483-6185-11e6-a910-42010a8a0fc0
spec:
  replicas: 4

 

변경사항을 확인한다.

k get sts cassandra
NAME        READY   AGE
cassandra   4/4     6m22s

 

Cassandra 삭제

# statefulset 삭제
grace=$(kubectl get pod cassandra-0 -o=jsonpath='{.spec.terminationGracePeriodSeconds}') \
  && kubectl delete statefulset -l app=cassandra \
  && echo "Sleeping ${grace} seconds" 1>&2 \
  && sleep $grace \
  && kubectl delete persistentvolumeclaim -l app=cassandra

# service 삭제
kubectl delete service -l app=cassandra

# 삭제 확인
k get svc,po,pv,pvc
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.100.0.1   <none>        443/TCP   56m
  • 너무 오래 걸린다. 수동으로 전부 지워줘도 된다.
  • `k delete pvc cassandra-data-cassandra-0 cassandra-data-cassandra-1...`

 

Kubectl Kui 설치

curl -LO https://github.com/kubernetes-sigs/kui/releases/download/v13.1.4/Kui-linux-x64.zip

unzip Kui-linux-x64.zip
# 아키텍처 확인

# 환경변수 등록
echo 'export PATH=$PATH:~/Kui-linux-x64' >> ~/.bashrc
source ~/.bashrc

# path 확인
echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/.krew/bin:/root/bin:/root/Kui-linux-x64

kubectl kui
/root/Kui-linux-x64/Kui: error while loading shared libraries: libatk-1.0.so.0: cannot open shared object file: No such file or directory

sudo yum install libatk-bridge-2.0.so.0 atk

# 라이브러리 링크 확인
ldd /root/Kui-linux-x64/Kui | grep not
        libcups.so.2 => not found
        libgtk-3.so.0 => not found
        libpango-1.0.so.0 => not found
        libcairo.so.2 => not found
        libXcomposite.so.1 => not found
        libXdamage.so.1 => not found
        libXfixes.so.3 => not found
        libXrandr.so.2 => not found
        libgbm.so.1 => not found
        libxkbcommon.so.0 => not found
        libasound.so.2 => not found

 sudo yum install cups-libs gtk3 pango cario libXcomposite libXdamage libXfixes libXrandr mesa-libgbm libxkbcommon alsa-lib
 

kubectl kui
[1019/004012.754239:FATAL:electron_main_delegate.cc(299)] Running as root without --no-sandbox is not supported. See https://crbug.com/638180.

 

WSL에서는 안되는거 같습니다. 아쉽네요.

 

Reference

https://kubernetes.io/docs/tutorials/stateful-application/cassandra/

https://kubernetes.io/docs/tutorials/stateful-application/cassandra/

https://cassandra.apache.org/_/cassandra-basics.html

https://github.com/kubernetes-sigs/kui

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'교육, 커뮤니티 후기 > DOIK (데이터베이스 오퍼레이터 인 쿠버네티스) 스터디' 카테고리의 다른 글

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