k8s中statefulset如何做pod负载均衡？

Question

从文档中，可以发现有一个 Stable Network ID 功能可用于 Pod NDS:

https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#stable-network-id

我试过了

service.yaml

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: logstash
  name: logstash
spec:
  selector:
    app: logstash
  ports:
    - name: "5044"
      port: 5044
      targetPort: 5044

statefulset.yaml

---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: logstash
spec:
  serviceName: "logstash"
  selector:
    matchLabels:
      app: logstash
  updateStrategy:
    type: RollingUpdate
  replicas: 2
  template:
    metadata:
      labels:
        app: logstash
    spec:
      containers:
      - name: logstash
        image: docker.elastic.co/logstash/logstash:7.10.0
        resources:
          limits:
            memory: 2Gi
        ports:
          - containerPort: 5044
        volumeMounts:
          - name: config-volume
            mountPath: /usr/share/logstash/config
          - name: logstash-pipeline-volume
            mountPath: /usr/share/logstash/pipeline
        command: ["/bin/sh","-c"]
        args:
          - bin/logstash -f /usr/share/logstash/pipeline/logstash.conf;
      volumes:
        - name: config-volume
          configMap:
            name: configmap-logstash
            items:
              - key: logstash.yml
                path: logstash.yml
        - name: logstash-pipeline-volume
          configMap:
            name: configmap-logstash
            items:
              - key: logstash.conf
                path: logstash.conf

configmap.yaml

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: configmap-filebeat
  labels:
    k8s-app: filebeat
data:
  filebeat.yml: |-
    filebeat.inputs:
      - type: log
        enabled: true
        paths:
          - /var/lib/nginx/access.json

    output.logstash:
      hosts: ["logstash-0.logstash.default.svc.cluster.local:5044", "logstash-1.logstash.default.svc.cluster.local:5044"]
      loadbalance: true

Filebeat 正在使用此配置部署到守护进程中。

这行不通。从 filebeat 的日志中得到：

2020-12-22T02:10:34.395Z    WARN    [transport] transport/tcp.go:52 DNS lookup failure "logstash-1.logstash.default.svc.cluster.local": lookup logstash-1.logstash.default.svc.cluster.local: no such host

如果使用这个配置，它可以工作：

    output.logstash:
      hosts: ["logstash.default.svc.cluster.local:5044"]

为什么在使用 Pod DNS 格式时会导致 DNS lookup failure 问题？使用此功能还有其他条件吗？那怎么办？

Answer 1

另请注意 StatefulSet documentation：

As mentioned in the limitations section, you are responsible for creating the Headless Service responsible for the network identity of the pods.

因此您有责任为 pods 创建 Headless Services，例如logstash-0 和 logstash-1.

k8s中statefulset如何做pod负载均衡？

How to do pod load balancing with statefulset in k8s?

dns

load-balancing

logstash

kubernetes

filebeat

service.yaml

statefulset.yaml

configmap.yaml