쿠버네티스 환경을 위한 Fluentd 기반 프로덕션 레벨 중앙 로깅 시스템 완벽 구축 가이드

# elasticsearch-statefulset.yaml
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: elasticsearch
  namespace: logging
spec:
  serviceName: elasticsearch
  replicas: 1 # 프로덕션 환경에서는 3 이상을 권장합니다.
  selector:
    matchLabels:
      app: elasticsearch
  template:
    metadata:
      labels:
        app: elasticsearch
    spec:
      containers:
      - name: elasticsearch
        image: docker.elastic.co/elasticsearch/elasticsearch:8.5.0
        resources:
          limits:
            cpu: 1000m
            memory: 2Gi
          requests:
            cpu: 100m
            memory: 1Gi
        ports:
        - containerPort: 9200
          name: rest
        - containerPort: 9300
          name: inter-node
        volumeMounts:
        - name: data
          mountPath: /usr/share/elasticsearch/data
        env:
        - name: discovery.type
          value: single-node # 단일 노드 설정. 클러스터 구성 시 변경 필요
        - name: ES_JAVA_OPTS
          value: "-Xms1g -Xmx1g" # requests.memory와 일치시키는 것이 좋습니다.
        - name: xpack.security.enabled
          value: "false" # 데모 목적으로 보안 기능 비활성화
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: "gp2" # 사용하는 스토리지 클래스로 변경
      resources:
        requests:
          storage: 10Gi
---
# elasticsearch-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: elasticsearch
  namespace: logging
spec:
  selector:
    app: elasticsearch
  ports:
  - port: 9200
    name: rest

# kibana-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: kibana
  namespace: logging
spec:
  replicas: 1
  selector:
    matchLabels:
      app: kibana
  template:
    metadata:
      labels:
        app: kibana
    spec:
      containers:
      - name: kibana
        image: docker.elastic.co/kibana/kibana:8.5.0
        resources:
          limits:
            cpu: 1000m
            memory: 1Gi
          requests:
            cpu: 100m
            memory: 500Mi
        env:
          - name: ELASTICSEARCH_HOSTS
            value: '["http://elasticsearch.logging:9200"]'
        ports:
        - containerPort: 5601
---
# kibana-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: kibana
  namespace: logging
spec:
  type: LoadBalancer # 외부 접근을 위해 LoadBalancer 또는 Ingress 사용
  selector:
    app: kibana
  ports:
  - port: 5601
    targetPort: 5601

# fluentd-rbac.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: fluentd
  namespace: logging
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: fluentd
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - namespaces
  verbs:
  - get
  - list
  - watch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: fluentd
roleRef:
  kind: ClusterRole
  name: fluentd
  apiGroup: rbac.authorization.k8s.io
subjects:
- kind: ServiceAccount
  name: fluentd
  namespace: logging

# fluentd-configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: fluentd-config
  namespace: logging
data:
  fluent.conf: |
    # ======== INPUTS ========
    <source>
      @type tail
      @id in_tail_container_logs
      path /var/log/containers/*.log
      pos_file /var/log/fluentd-containers.log.pos
      tag kubernetes.*
      read_from_head true
      <parse>
        @type cri
      </parse>
    </source>

    # ======== FILTERS ========
    <filter kubernetes.**>
      @type kubernetes_metadata
      @id filter_kube_metadata
    </filter>

    # ======== OUTPUTS ========
    <match kubernetes.**>
      @type elasticsearch
      @id out_es
      host elasticsearch.logging.svc.cluster.local
      port 9200
      log_level info
      include_tag_key true
      type_name _doc
      logstash_format true
      logstash_prefix fluentd
      logstash_dateformat %Y%m%d
      <buffer>
        @type file
        path /var/log/fluentd-buffers/kubernetes.system.buffer
        flush_mode interval
        retry_type exponential_backoff
        flush_thread_count 2
        flush_interval 5s
        retry_forever true
        retry_max_interval 30
        chunk_limit_size 2M
        queue_limit_length 8
        overflow_action block
      </buffer>
    </match>

# fluentd-daemonset.yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: fluentd
  namespace: logging
spec:
  selector:
    matchLabels:
      app: fluentd
  template:
    metadata:
      labels:
        app: fluentd
    spec:
      serviceAccountName: fluentd
      tolerations:
      - key: node-role.kubernetes.io/master
        effect: NoSchedule
      containers:
      - name: fluentd
        image: fluent/fluentd-kubernetes-daemonset:v1.15-debian-elasticsearch8-1
        env:
        - name: FLUENT_ELASTICSEARCH_HOST
          value: "elasticsearch.logging.svc.cluster.local"
        - name: FLUENT_ELASTICSEARCH_PORT
          value: "9200"
        resources:
          limits:
            memory: 512Mi
          requests:
            cpu: 100m
            memory: 200Mi
        volumeMounts:
        - name: varlog
          mountPath: /var/log
        - name: varlibdockercontainers
          mountPath: /var/lib/docker/containers
          readOnly: true
        - name: config-volume
          mountPath: /fluentd/etc/fluent.conf
          subPath: fluent.conf
      terminationGracePeriodSeconds: 30
      volumes:
      - name: varlog
        hostPath:
          path: /var/log
      - name: varlibdockercontainers
        hostPath:
          path: /var/lib/docker/containers
      - name: config-volume
        configMap:
          name: fluentd-config