为啥 Elasticsearch 集群只能发现 1 个节点？

Posted 2023-03-22

【中文标题】为啥 Elasticsearch 集群只能发现 1 个节点？

【英文标题】：Why does Elasticsearch cluster only discover 1 node?为什么 Elasticsearch 集群只能发现 1 个节点？

【发布时间】：2021-09-15 09:39:11

【问题描述】：

我在 Kubernetes 中部署了 Elasticsearch 7.10.1 集群。 k8s规范的配置如下所示。

我将replicas: 3 配置为有 3 个 pod 作为 3 个节点工作以形成一个 Elasticsearch 集群。我可以看到所有三个节点都在运行。

$ kubectl get pods
NAME                      READY   STATUS    RESTARTS   AGE
es-0                      1/1     Running   0          2m58s
es-1                      1/1     Running   0          5m43s
es-2                      1/1     Running   0          8m23s

但是 Elasticsearch 只能识别一个节点。以下是_cluster/health的回复：

  "cluster_name" : "elk-cluster",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 1,
  "number_of_data_nodes" : 1,
  "active_primary_shards" : 0,
  "active_shards" : 0,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 0,
  "delayed_unassigned_shards" : 0,
  "number_of_pending_tasks" : 0,
  "number_of_in_flight_fetch" : 0,
  "task_max_waiting_in_queue_millis" : 0,
  "active_shards_percent_as_number" : 100.0

当我运行 _cat/nodes 时，它只显示 1 个节点。但它每次显示不同的节点名称。所以输出在：

10.0.2.185 38 32 3 0.05 0.48 0.38 cdhilmrstw * es-2

or

10.0.2.220 33 31 2 0.27 0.60 0.31 cdhilmrstw * es-0

or

10.0.1.240 14 96 1 0.04 0.68 0.49 cdhilmrstw * es-1

集群似乎一次只能找到一个节点，并且不断在不同节点之间切换。

如何在 Elasticsearch 上形成 3 个节点？

k8s 规格：

apiVersion: v1
kind: ConfigMap
metadata:
  name: es-config
data:
  elasticsearch.yml: |
    cluster.name: elk-cluster
    network.host: "0.0.0.0"
    bootstrap.memory_lock: false
    discovery.zen.ping.unicast.hosts: elasticsearch-cluster
    discovery.zen.minimum_master_nodes: 2
    node.max_local_storage_nodes: 9
  ES_JAVA_OPTS: -Xms2g -Xmx4g
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: es
  namespace: default
spec:
  serviceName: es-entrypoint
  replicas: 3
  selector:
    matchLabels:
      name: es
  template:
    metadata:
      labels:
        name: es
    spec:
      volumes:
        - name: es-config
          configMap:
            name: es-config
            items:
              - key: elasticsearch.yml
                path: elasticsearch.yml
        - name: persistent-storage
          persistentVolumeClaim:
            claimName: es-claim
      initContainers:
        - name: permissions-fix
          image: busybox
          volumeMounts:
            - name: persistent-storage
              mountPath: /usr/share/elasticsearch/data
          command: [ 'chown' ]
          args: [ '1000:1000', '/usr/share/elasticsearch/data' ]
      containers:
        - name: es
          image: elasticsearch:7.10.1
          resources:
            requests:
              cpu: 2
              memory: 8
          ports:
            - name: http
              containerPort: 9200
            - containerPort: 9300
              name: inter-node
          volumeMounts:
            - name: es-config
              mountPath: /usr/share/elasticsearch/config/elasticsearch.yml
              subPath: elasticsearch.yml
            - name: persistent-storage
              mountPath: /usr/share/elasticsearch/data
---
apiVersion: v1
kind: Service
metadata:
  name: es-entrypoint
spec:
  selector:
    name: es
  ports:
    - port: 9200
      targetPort: 9200
      protocol: TCP
  clusterIP: None

【问题讨论】：

请检查$ kubectl logs es-0 是否有错误。如果有，也添加错误消息。

【参考方案1】：

这些是 Elasticsearch 6.x 版的发现设置：

 discovery.zen.ping.unicast.hosts: elasticsearch-cluster
 discovery.zen.minimum_master_nodes: 2

在 7.x 中已弃用。您需要更新您的发现设置：

discovery.seed_hosts:
  - es-entrypoint.default.svc # headless service dns
cluster.initial_master_nodes:
  - es-0
  - es-1
  - es-2