在Kubernetes中更新configmap时刷新后台启动Pod

Question

当与后台程序集关联的Kubernetes Pod的configmap更新时，如何自动重新启动它们？

根据kubernetes文档，当configmap卷挂载更新时，它会自动更新POD。但是，我并不认为后台进程集会发生这种情况。我错过了什么？

apiVersion: v1
kind: ConfigMap
metadata:
  name: fluent-bit-update
  namespace: default
  labels:
    k8s-app: fluent-bit
data:
  # Configuration files: server, input, filters and output
  # ======================================================
  fluent-bit.conf: |
    [SERVICE]
        Flush         1
        Log_Level     info
        Daemon        off
        Parsers_File  parsers.conf


    @INCLUDE input-kubernetes.conf
    @INCLUDE filter-kubernetes.conf
    @INCLUDE output-logaggregator.conf

  input-kubernetes.conf: |
    [INPUT]
        Name              tail
        Tag               kube.*
        Path              /var/log/containers/abc.log
        Parser            docker
        DB                /var/log/tail-containers-state.db
        DB.Sync           Normal
        Mem_Buf_Limit     5MB
        Skip_Long_Lines   On
        Refresh_Interval  10
        Rotate_Wait      60
        Docker_Mode      On

  filter-kubernetes.conf: |

    [FILTER]
        Name                kubernetes
        Match               kube.*
        Kube_URL            https://kubernetes.default.svc:443
        Kube_CA_File        /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
        Kube_Token_File     /var/run/secrets/kubernetes.io/serviceaccount/token
        Kube_Tag_Prefix     kube.var.log.conatiners.
        Merge_Log           On
        Keep_Log            Off
        K8S-Logging.Parser  On
        K8S-Logging.Exclude Off
        Labels              On
        Annotations         On

  output-kubernetes.conf: |

    [OUTPUT]
        Name              cloudwatch
        Match             kube.*
        region            us-west-2
        log_group_name    fluent-bit-cloudwatch
        log_stream_prefix from-fluent-bit
        auto_create_group true

  parsers.conf: |

    [PARSER]
        Name         docker
        Format       json
        Time_Key     time
        Time_Format  %Y-%m-%dT%H:%M:%S.%L
        Time_Keep    On
        Decode_Field_As   escaped_utf8    log    do_next
        Decode_Field_As   json       log

    [PARSER]
        Name         docker_default
        Format       json
        Time_Key     time
        Time_Format  %Y-%m-%dT%H:%M:%S.%L
        Time_Keep    On

apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  name: fluent-bit-update
  namespace: default
  labels:
    k8s-app: fluent-bit-logging
    version: v1
    kubernetes.io/cluster-service: "true"
spec:
  template:
    metadata:
      labels:
        k8s-app: fluent-bit-logging
        version: v1
        kubernetes.io/cluster-service: "true"
      annotations:
        prometheus.io/scrape: "true"
        prometheus.io/port: "2020"
        prometheus.io/path: /api/v1/metrics/prometheus
    spec:
      containers:
        - name: aws-for-fluent-bit
          image: amazon/aws-for-fluent-bit:latest
          imagePullPolicy: Always
          ports:
            - containerPort: 2020
          volumeMounts:
            - name: varlog
              mountPath: /var/log
            - name: varlibdockercontainers
              mountPath: /var/lib/docker/containers
              readOnly: true
            - name: fluent-bit-volume
              mountPath: /fluent-bit/etc/
      terminationGracePeriodSeconds: 10
      volumes:
        - name: varlog
          hostPath:
            path: /var/log
        - name: varlibdockercontainers
          hostPath:
            path: /var/lib/docker/containers
        - name: fluent-bit-volume
          configMap:
            name: fluent-bit-update
      serviceAccountName: fluent-bit
      tolerations:
        - key: node-role.kubernetes.io/master
          operator: Exists
          effect: NoSchedule
        - operator: "Exists"
          effect: "NoExecute"
        - operator: "Exists"
          effect: "NoSchedule"

当我更新configmap中的path字段以读取另一个日志文件时，虽然我看到卷挂载正在更新，但我看不到POD正在接收更改，除非我删除并重新创建后台启动。

有没有一种方法可以在不重新启动后台启动的情况下自动实现这一点？我希望得到一些关于这一点的指导。谢谢

Answer 1

根据您指出的文档，Kubernetes将更新configmap（在您的情况中为fluent-bit配置），但选择更新的配置是应用程序的职责。通常，应用程序在启动时接受配置，但要定期更新配置，您的应用程序应该支持此配置，或者应该使用另一个模块（如配置更新器），当配置发生变化时，该模块将重新启动应用程序（而不是重新启动pod）。对于fluent-bit，您可以参考github的动态配置问题。普罗米修斯已经这样支持了。