CockroachDB的部署

2 年 ago

文, 翔

4 minutes

现在为了实现POST方法，我们需要部署存储。根据工作负载的特性和团队的技术堆栈，可以选择适合的数据存储方式，没有固定的规定。有些团队使用Mongo，有些团队根据访问方式选择使用etcd等，选择的理由各种各样。我所在的团队也在使用几种不同的存储方式，但对于简单的Web应用，通常选择CockroachDB。

这个分散式的SQL数据库与Postgres兼容，并且没有特殊的使用方式，非常易于操作。

我希望将数据再次保存在这个CockroachDB中。

部署CockroachDB

我们来看一下部署CockroachDB所需的Kubernetes清单文件。
大致上和这里列出的步骤相同。

apiVersion: policy/v1beta1
kind: PodDisruptionBudget
metadata:
  name: cockroachdb-budget
  namespace: qiita
  labels:
    app: cockroachdb
spec:
  selector:
    matchLabels:
      app: cockroachdb
  maxUnavailable: 1
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: cockroachdb
  namespace: qiita
  labels:
    app: cockroachdb
spec:
  serviceName: "cockroachdb"
  replicas: 3
  selector:
    matchLabels:
      app: cockroachdb
  template:
    metadata:
      labels:
        app: cockroachdb
    spec:
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
              labelSelector:
                matchExpressions:
                - key: app
                  operator: In
                  values:
                  - cockroachdb
              topologyKey: kubernetes.io/hostname
      containers:
      - name: cockroachdb
        image: cockroachdb/cockroach:v2.1.4
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 26257
          name: grpc
        - containerPort: 8080
          name: http
        livenessProbe:
          httpGet:
            path: "/health"
            port: http
            scheme: HTTP
          initialDelaySeconds: 30
          periodSeconds: 5
        readinessProbe:
          httpGet:
            path: "/health?ready=1"
            port: http
            scheme: HTTP
          initialDelaySeconds: 60
          failureThreshold: 2
        volumeMounts:
        - name: datadir
          mountPath: /cockroach/cockroach-data
        env:
        - name: COCKROACH_CHANNEL
          value: kubernetes-insecure
        command:
        - "/bin/bash"
        - "-ecx"
        # The use of qualified `hostname -f` is crucial:
        # Other nodes aren't able to look up the unqualified hostname.
        - "exec /cockroach/cockroach start --logtostderr --insecure --advertise-host $(hostname -f) --http-addr 0.0.0.0 --join cockroachdb-0.cockroachdb,cockroachdb-1.cockroachdb,cockroachdb-2.cockroachdb --cache 25% --max-sql-memory 25%"
      # No pre-stop hook is required, a SIGTERM plus some time is all that's
      # needed for graceful shutdown of a node.
      terminationGracePeriodSeconds: 60
      volumes:
      - name: datadir
        persistentVolumeClaim:
          claimName: datadir
  podManagementPolicy: Parallel
  updateStrategy:
    type: RollingUpdate
  volumeClaimTemplates:
  - metadata:
      name: datadir
    spec:
      accessModes:
      - "ReadWriteOnce"
      resources:
        requests:
          storage: 100Gi

apiVersion: v1
kind: Service
metadata:
  # This service is meant to be used by clients of the database. It exposes a ClusterIP that will
  # automatically load balance connections to the different database pods.
  name: cockroachdb-proxy
  namespace: qiita
  labels:
    app: cockroachdb
spec:
  ports:
  # The main port, served by gRPC, serves Postgres-flavor SQL, internode
  # traffic and the cli.
  - port: 26257
    targetPort: 26257
    name: grpc
  # The secondary port serves the UI as well as health and debug endpoints.
  - port: 8000
    targetPort: 8000
    name: http
  selector:
    app: cockroachdb
---
apiVersion: v1
kind: Service
metadata:
  # This service only exists to create DNS entries for each pod in the stateful
  # set such that they can resolve each other's IP addresses. It does not
  # create a load-balanced ClusterIP and should not be used directly by clients
  # in most circumstances.
  name: cockroachdb
  namespace: qiita
  labels:
    app: cockroachdb
  annotations:
    # Enable automatic monitoring of all instances when Prometheus is running in the cluster.
    prometheus.io/scrape: "true"
    prometheus.io/path: "_status/vars"
    prometheus.io/port: "8000"
spec:
  ports:
  - port: 26257
    targetPort: 26257
    name: grpc
  - port: 8000
    targetPort: 8000
    name: http
  # We want all pods in the StatefulSet to have their addresses published for
  # the sake of the other CockroachDB pods even before they're ready, since they
  # have to be able to talk to each other in order to become ready.
  publishNotReadyAddresses: true
  clusterIP: None
  selector:
    app: cockroachdb

实际上，为了在安全模式下启动，有一些方法，如部署认证机构或证书更新的副车等，但在这里不详细展示。

那么让我们部署一下吧。

$ kubectl apply -f kubernetes/cockroach-statefulset.yaml
poddisruptionbudget.policy/cockroachdb-budget created
statefulset.apps/cockroachdb created
$ kubectl apply -f kubernetes/cockroach-service.yaml
service/cockroachdb-proxy created
service/cockroachdb created

$ kubectl -n qiita get pods
NAME                                          READY   STATUS    RESTARTS   AGE
cockroachdb-0                                 0/1     Running   0          87s
cockroachdb-1                                 0/1     Running   0          87s
cockroachdb-2                                 0/1     Running   0          86s
qiita-advent-calendar-2019-7c885c5698-hwkts   1/1     Running   1          5d21h

$ kubectl -n qiita get statefulsets.apps
NAME          READY   AGE
cockroachdb   0/3     2m52s

$ kubectl -n qiita get service
NAME                         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)              AGE
cockroachdb                  ClusterIP   None            <none>        26257/TCP,8000/TCP   15m
cockroachdb-proxy            ClusterIP   10.111.34.61    <none>        26257/TCP,8000/TCP   15m
qiita-advent-calendar-2019   ClusterIP   10.108.124.86   <none>        8080/TCP             5d21h

$ kubectl -n qiita get poddisruptionbudgets.policy
NAME                 MIN AVAILABLE   MAX UNAVAILABLE   ALLOWED DISRUPTIONS   AGE
cockroachdb-budget   N/A             1                 0                     3m17s

资源的创建暂时完成了。

Job的执行

下一步，我们将执行用于设置Cockroach群集的初始作业。

apiVersion: batch/v1
kind: Job
metadata:
  name: cockroach-init
  namespace: qiita
  labels:
    app: cockroachdb
spec:
  template:
    spec:
      containers:
      - name: cluster-init
        image: cockroachdb/cockroach:v2.1.4
        imagePullPolicy: IfNotPresent
        command:
        - "/cockroach/cockroach"
        - "init"
        - "--insecure"
        - "--host=cockroachdb-0.cockroachdb"
      restartPolicy: OnFailure

执行。

$ kubectl apply -f kubernetes/cockroach-init-job.yaml
job.batch/cockroach-init created

$ kubectl -n qiita get jobs.batch
NAME             COMPLETIONS   DURATION   AGE
cockroach-init   1/1           3s         8s

$ kubectl -n qiita get pod
NAME                                          READY   STATUS      RESTARTS   AGE
cockroach-init-5zmpg                          0/1     Completed   0          15s
cockroachdb-0                                 1/1     Running     0          8m26s
cockroachdb-1                                 1/1     Running     0          8m26s
cockroachdb-2                                 1/1     Running     0          8m25s
qiita-advent-calendar-2019-7c885c5698-hwkts   1/1     Running     1          5d21h

可以确认Pod已经准备就绪。

创建数据库和用户

我觉得……，但是由于毛笔的运笔不太理想，我暂时想把它放在一边，明天再看一下。笑