K8S结合ELK搭建企业日志收集平台

作者：李毓

首先我们要思考一下，K8S中收集日志与传统条件下的日志收集有什么区别。他一般是收集哪些日志？确定收集日志类型之后又是怎么去收集的？如果日志还是放到容器内部，会随着容器删除而被删除。容器数量很多，按照传统的查看日志方式已变不太现实。K8s本身特性是容器日志输出控制台，本身Docker提供了一种日志采集能力。如果落地到本地文件，目前还没有一种好的采集方式。所以新扩容Pod属性信息（日志文件路径，日志源）可能发生变化

流程和传统采集是类似的，如下图。

一般来说，我们用的日志收集方案有两种，一种是node上部署日志的收集程序，比如用daemonset方式部署，对本节点容器下的目录进行采集。并且把容器内的目录挂载到宿主机目录上面。目录为对本节点/var/log/kubelet/pods和
/var/lib/docker/containers/两个目录下的日志进行采集。还有一种是Pod中附加专用日志收集的容器 每个运行应用程序的Pod中增加一个日志收集容器，使用emtyDir共享日志目录让日志收集程序读取到。这里先探讨第二种方案。

约定K8S集群为三台
k8s-mater:192.168,.187.137
k8s-node1:192.168,.187.138
k8s-node2:192.168,.187.139

执行以下脚本之前要先创建存储，这个参考之前的监控文档。

在master上执行
elasticsearch.yaml

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: elasticsearch
  namespace: kube-system
  labels:
    k8s-app: elasticsearch
spec:
  serviceName: elasticsearch
  selector:
    matchLabels:
      k8s-app: elasticsearch
  template:
    metadata:
      labels:
        k8s-app: elasticsearch
    spec:
      containers:
      - image: elasticsearch:7.3.2
        name: elasticsearch
        resources:
          limits:
            cpu: 1
            memory: 2Gi
          requests:
            cpu: 0.5 
            memory: 500Mi
        env:
          - name: "discovery.type"
            value: "single-node"
          - name: ES_JAVA_OPTS
            value: "-Xms512m -Xmx2g" 
        ports:
        - containerPort: 9200
          name: db
          protocol: TCP
        volumeMounts:
        - name: elasticsearch-data
          mountPath: /usr/share/elasticsearch/data
  volumeClaimTemplates:
  - metadata:
      name: elasticsearch-data
    spec:
      storageClassName: "managed-nfs-storage"
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 20Gi

---

apiVersion: v1
kind: Service
metadata:
  name: elasticsearch
  namespace: kube-system
spec:
  clusterIP: None
  ports:
  - port: 9200
    protocol: TCP
    targetPort: db
  selector:
    k8s-app: elasticsearch

filebeat.yaml

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: filebeat-config
  namespace: kube-system
  labels:
    k8s-app: filebeat
data:
  filebeat.yml: |-
    filebeat.config:
      inputs:
        # Mounted `filebeat-inputs` configmap:
        path: ${path.config}/inputs.d/*.yml
        # Reload inputs configs as they change:
        reload.enabled: false
      modules:
        path: ${path.config}/modules.d/*.yml
        # Reload module configs as they change:
        reload.enabled: false

    # To enable hints based autodiscover, remove `filebeat.config.inputs` configuration and uncomment this:
    #filebeat.autodiscover:
    #  providers:
    #    - type: kubernetes
    #      hints.enabled: true

    output.elasticsearch:
      hosts: ['${ELASTICSEARCH_HOST:elasticsearch}:${ELASTICSEARCH_PORT:9200}']
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: filebeat-inputs
  namespace: kube-system
  labels:
    k8s-app: filebeat
data:
  kubernetes.yml: |-
    - type: docker
      containers.ids:
      - "*"
      processors:
        - add_kubernetes_metadata:
            in_cluster: true
---
apiVersion: apps/v1 
kind: DaemonSet
metadata:
  name: filebeat
  namespace: kube-system
  labels:
    k8s-app: filebeat
spec:
  selector:
    matchLabels:
      k8s-app: filebeat
  template:
    metadata:
      labels:
        k8s-app: filebeat
    spec:
      serviceAccountName: filebeat
      terminationGracePeriodSeconds: 30
      containers:
      - name: filebeat
        image: elastic/filebeat:7.3.2
        args: [
          "-c", "/etc/filebeat.yml",
          "-e",
        ]
        env:
        - name: ELASTICSEARCH_HOST
          value: elasticsearch
        - name: ELASTICSEARCH_PORT
          value: "9200"
        securityContext:
          runAsUser: 0
          # If using Red Hat OpenShift uncomment this:
          #privileged: true
        resources:
          limits:
            memory: 200Mi
          requests:
            cpu: 100m
            memory: 100Mi
        volumeMounts:
        - name: config
          mountPath: /etc/filebeat.yml
          readOnly: true
          subPath: filebeat.yml
        - name: inputs
          mountPath: /usr/share/filebeat/inputs.d
          readOnly: true
        - name: data
          mountPath: /usr/share/filebeat/data
        - name: varlibdockercontainers
          mountPath: /var/lib/docker/containers
          readOnly: true
      volumes:
      - name: config
        configMap:
          defaultMode: 0600
          name: filebeat-config
      - name: varlibdockercontainers
        hostPath:
          path: /var/lib/docker/containers
      - name: inputs
        configMap:
          defaultMode: 0600
          name: filebeat-inputs
      # data folder stores a registry of read status for all files, so we don't send everything again on a Filebeat pod restart
      - name: data
        hostPath:
          path: /var/lib/filebeat-data
          type: DirectoryOrCreate
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: filebeat
subjects:
- kind: ServiceAccount
  name: filebeat
  namespace: kube-system
roleRef:
  kind: ClusterRole
  name: filebeat
  apiGroup: rbac.authorization.k8s.io
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
  name: filebeat
  labels:
    k8s-app: filebeat
rules:
- apiGroups: [""] # "" indicates the core API group
  resources:
  - namespaces
  - pods
  verbs:
  - get
  - watch
  - list
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: filebeat
  namespace: kube-system
  labels:
    k8s-app: filebeat
---

kibana.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: kibana
  namespace: kube-system
  labels:
    k8s-app: kibana
spec:
  replicas: 1
  selector:
    matchLabels:
      k8s-app: kibana
  template:
    metadata:
      labels:
        k8s-app: kibana
    spec:
      containers:
      - name: kibana
        image: kibana:7.3.2
        resources:
          limits:
            cpu: 1
            memory: 500Mi
          requests:
            cpu: 0.5 
            memory: 200Mi
        env:
          - name: ELASTICSEARCH_HOSTS
            value: http://elasticsearch-0.elasticsearch.kube-system:9200
          - name: I18N_LOCALE
            value: zh-CN
        ports:
        - containerPort: 5601
          name: ui
          protocol: TCP

---
apiVersion: v1
kind: Service
metadata:
  name: kibana
  namespace: kube-system
spec:
  type: NodePort
  ports:
  - port: 5601
    protocol: TCP
    targetPort: ui
    nodePort: 30601
  selector:
    k8s-app: kibana

新建的时候一直建不上，发现是由于之前实验环境PV没有删除，先将PV删除。
一般用常规方法难以删除，可以尝试强制从数据库删除。

kubectl patch pv pvc-4163c9d4-44cb-4c50-aa20-412f388d989e -p '{"metadata":{"finalizers":null}}'

登录进去之后创建索引

在查看K8S一些pod，命名空间，service的日志，全都收集到了。

尝试安装一个nginx，然后捕捉他的日志。

kubectl create deployment web --image=nginx
kubectl expose deployment web --port=80 --target-port=80 --name=web --type=NodePort

curl 10.244.2.12

再去查看kinbana

成功获取日志
我们再看看K8S组件日志的收集

apiVersion: v1
kind: ConfigMap
metadata:
  name: k8s-logs-filebeat-config
  namespace: kube-system 

data:
  filebeat.yml: |
    filebeat.inputs:
      - type: log
        paths:
          - /var/log/messages  
        fields:
          app: k8s 
          type: module 
        fields_under_root: true

    setup.ilm.enabled: false
    setup.template.name: "k8s-module"
    setup.template.pattern: "k8s-module-*"

    output.elasticsearch:
      hosts: ['elasticsearch.kube-system:9200']
      index: "k8s-module-%{+yyyy.MM.dd}"

---

apiVersion: apps/v1
kind: DaemonSet 
metadata:
  name: k8s-logs
  namespace: kube-system
spec:
  selector:
    matchLabels:
      project: k8s 
      app: filebeat
  template:
    metadata:
      labels:
        project: k8s
        app: filebeat
    spec:
      containers:
      - name: filebeat
        image: elastic/filebeat:7.3.2
        args: [
          "-c", "/etc/filebeat.yml",
          "-e",
        ]
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
          limits:
            cpu: 500m
            memory: 500Mi
        securityContext:
          runAsUser: 0
        volumeMounts:
        - name: filebeat-config
          mountPath: /etc/filebeat.yml
          subPath: filebeat.yml
        - name: k8s-logs 
          mountPath: /var/log/messages
      volumes:
      - name: k8s-logs
        hostPath: 
          path: /var/log/messages
      - name: filebeat-config
        configMap:
          name: k8s-logs-filebeat-config

组件日志也可以查看到了。