ELK 日志系统收集K8s中日志

容器特性给日志采集带来的困难

• K8s弹性伸缩性：导致不能预先确定采集的目标
• 容器隔离性：容器的文件系统与宿主机是隔离，导致日志采集器读取日志文件受阻。

日志按体现方式分类

应用程序日志记录体现方式分为两类：
• 标准输出：输出到控制台，使用kubectl logs可以看到。
例如 nginx日志是将访问日志输出到标准输出，可以用kubectl log 查看

kubectl  logs ==>> apiserver ==>> kubecet ==>> docker api ==>><container-id>-json.log  

• 日志文件：写到容器的文件系统的文件。

Kubernetes应用日志收集

针对标准输出：以DaemonSet方式在每个Node上部署一个日志收集程序，采集
/var/lib/docker/containers/目录下所有容器日志。

针对容器中日志文件：在Pod中增加一个容器运行日志采集器，使用emptyDir共享日志目录让日志采集器读取到日志文件。

ELK 日志系统

ELK 是三个开源软件的缩写，提供一套完整的企业级日志平台解决方案。
分别是：
• Elasticsearch：搜索、分析和存储数据
• Logstash ：采集日志、格式化、过滤，最后将数据
推送到Elasticsearch存储
• Kibana：数据可视化
• Beats ：集合了多种单一用途数据采集器，用于实现从边缘机器向 Logstash 和 Elasticsearch 发送数
据。里面应用最多的是Filebeat，是一个轻量级日志采集器。

轻量级日志：graylog、grafana loki

搭建日志系统：
• elasticsearch.yaml # ES数据库
• kibana.yaml # 可视化展示
日志收集：
• filebeat-kubernetes.yaml # 采集所有容器标准输出
• app-log-stdout.yaml # 标准输出测试应用
• app-log-logfile.yaml # 日志文件测试应用

针对标准输出：在每个节以deamsent方式部署filebeat，采集节点上所有的日志文件，目录为/var/lib/docker/containers//容器id/xxxx-json.log

kubectl apply -f elasticsearch.yaml 
kubectl apply -f kibana.yaml 
kubectl apply -f filebeat-kubernetes.ya

 #elasticsearch.yaml
 apiVersion: apps/v1
kind: Deployment
metadata:
  name: elasticsearch
  namespace: ops
  labels:
    k8s-app: elasticsearch
spec:
  replicas: 1
  selector:
    matchLabels:
      k8s-app: elasticsearch
  template:
    metadata:
      labels:
        k8s-app: elasticsearch
    spec:
      containers:
      - image: elasticsearch:7.9.2
        name: elasticsearch
        resources:
          limits:
            cpu: 2
            memory: 3Gi
          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
      volumes:
      - name: elasticsearch-data
        persistentVolumeClaim:
          claimName: es-pvc

---

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: es-pvc
  namespace: ops
spec:
  storageClassName: "managed-nfs-storage"
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 10Gi

---

apiVersion: v1
kind: Service
metadata:
  name: elasticsearch
  namespace: ops
spec:
  ports:
  - port: 9200
    protocol: TCP
    targetPort: 9200
  selector:
    k8s-app: elasticsearch

#kibana.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: kibana
  namespace: ops
  labels:
    k8s-app: kibana
spec:
  replicas: 1
  selector:
    matchLabels:
      k8s-app: kibana
  template:
    metadata:
      labels:
        k8s-app: kibana
    spec:
      containers:
      - name: kibana
        image: kibana:7.9.2
        resources:
          limits:
            cpu: 2
            memory: 2Gi
          requests:
            cpu: 0.5
            memory: 500Mi
        env:
          - name: ELASTICSEARCH_HOSTS
            value: http://10.244.169.139:9200
          - name: I18N_LOCALE
            value: zh-CN
        ports:
        - containerPort: 5601
          name: ui
          protocol: TCP

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


#filebeat-kubernetes.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: filebeat-config
  namespace: ops
  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

    output.elasticsearch:
      hosts: ['elasticsearch.ops:9200']
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: filebeat-inputs
  namespace: ops
  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: ops
  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:7.9.2
        args: [
          "-c", "/etc/filebeat.yml",
          "-e",
        ]
        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/v1
kind: ClusterRoleBinding
metadata:
  name: filebeat
subjects:
- kind: ServiceAccount
  name: filebeat
  namespace: ops
roleRef:
  kind: ClusterRole
  name: filebeat
  apiGroup: rbac.authorization.k8s.io
---
apiVersion: rbac.authorization.k8s.io/v1
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: ops
  labels:
    k8s-app: filebeat

可视化展示日志：

1. 查看索引（日志记录集合）：Management -> Stack Management -> 索引管理
2. 将索引关联到Kibana：索引模式 -> 创建 -> 匹配模式 -> 选择时间戳
3. 在Discover选择索引模式查看日志

将索引关联到Kibana
Discover选择索引模式查看日志

按条件查询

二、针对容器中日志文件

#app-log-logfile.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-log-logfile
spec:
  replicas: 3
  selector:
    matchLabels:
      project: microservice
      app: nginx-logfile
  template:
    metadata:
      labels:
        project: microservice
        app: nginx-logfile
    spec:
      containers:
      # 应用容器
      - name: nginx
        image: lizhenliang/nginx-php
        # 将数据卷挂载到日志目录
        volumeMounts:
        - name: nginx-logs
          mountPath: /usr/local/nginx/logs
      # 日志采集器容器
      - name: filebeat
        image: elastic/filebeat:7.9.2
        args: [
          "-c", "/etc/filebeat.yml",
          "-e",
        ]
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
          limits:
            memory: 500Mi
        securityContext:
          runAsUser: 0
        volumeMounts:
        # 挂载filebeat配置文件
        - name: filebeat-config
          mountPath: /etc/filebeat.yml
          subPath: filebeat.yml
        # 将数据卷挂载到日志目录
        - name: nginx-logs
          mountPath: /usr/local/nginx/logs
      # 数据卷共享日志目录
      volumes:
      - name: nginx-logs
        emptyDir: {}
      - name: filebeat-config
        configMap:
          name: filebeat-nginx-config
---
apiVersion: v1
kind: Service
metadata:
  name: app-log-logfile
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    project: microservice
    app: nginx-logfile
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: filebeat-nginx-config

data:
  # 配置文件保存在ConfigMap
  filebeat.yml: |-
    filebeat.inputs:
      - type: log
        paths:
          - /usr/local/nginx/logs/access.log
        # tags: ["access"]
        fields_under_root: true
        fields:
          project: microservice #项目名称
          app: nginx            #pod名称

    setup.ilm.enabled: false
    setup.template.name: "nginx-access"
    setup.template.pattern: "nginx-access-*"

    output.elasticsearch:
      hosts: ['elasticsearch.ops:9200']
      index: "nginx-access-%{+yyyy.MM.dd}" #索引名称

kubectl apply -f app-log-logfile.yaml 

kibana建立索引，查看日志