EFK (Elasticsearch + Fluentd + Kibana) 是kubernetes官方推薦的日誌收集方案,我們一起了解一下fluentd是如何收集kubernetes叢集日誌的,慶祝一下fluentd從 CNCF 畢業。開始之前,希望你已經讀過Docker 容器日誌分析, 本文是其延生的第二篇。
注意 需要和ELK(Elasticsearch + Logstash + Kibana) 以及EFK(Elasticsearch + Filebeat + Kibana)區分,後一個EFK一般是原生部署。
CNCF , 全稱Cloud Native Computing Foundation(雲原生計算基金會),kubernetes也是其旗下,或者說大多數容器雲專案都是其旗下。
部署EFK
k8s中部署efk,所用的yaml檔案在 github.com/kubernetes/… ,你可以使用文章附錄提供的指令碼進行下載。
下載完成後執行 cd fluentd-elasticsearch && kubectl apply -f .
命令進行部署。
檢查elasticsearch和kibana service:
$ kubectl get svc -n kube-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
elasticsearch-logging NodePort 10.97.248.209 <none> 9200:32126/TCP 23d
kibana-logging ClusterIP 10.103.126.183 <none> 5601/TCP 23d
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檢查fluentd DaemonSet:
$ kubectl get ds -n kube-system
NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE
fluentd-es-v2.4.0 2 2 2 2 2 <none> 23d
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這裡我們知道了fluentd是以daemonset方式執行的,es和kibana是service方式。
注意 elasticsearch 預設部署檔案是沒有持久化的,如果需要持久化,需要調整其PVC設定。
fluentd 功能分析
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檢視fluentd的型別,沒什麼好說的
apiVersion: apps/v1 kind: DaemonSet metadata: name: fluentd-es-v2.2.1 namespace: kube-system 複製程式碼
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檢視fluentd日誌收集
containers: - name: fluentd-es image: k8s.gcr.io/fluentd-elasticsearch:v2.2.0 ... volumeMounts: - name: varlog mountPath: /var/log - name: varlibdockercontainers mountPath: /var/lib/docker/containers readOnly: true - name: config-volume mountPath: /etc/fluent/config.d ... volumes: - name: varlog hostPath: path: /var/log - name: varlibdockercontainers hostPath: path: /var/lib/docker/containers - name: config-volume configMap: name: fluentd-es-config-v0.1.6 複製程式碼
這裡可以清晰的看到,fluentd以daemonset方式運作,然後把系統的
/var/lib/docker/containers
掛載,這個目錄我們在Docker 容器日誌分析中介紹過,這是docker容器日誌存放路徑, 這樣fluentd就完成了對容器預設日誌的讀取。fluentd的配置檔案是以configmap形式載入,繼續往下看看。
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收集容器日誌配置
收集容器日誌主要在 containers.input.conf,如下:
<source> @id fluentd-containers.log @type tail path /var/log/containers/*.log pos_file /var/log/es-containers.log.pos tag raw.kubernetes.* read_from_head true <parse> @type multi_format <pattern> format json time_key time time_format %Y-%m-%dT%H:%M:%S.%NZ </pattern> <pattern> format /^(?<time>.+) (?<stream>stdout|stderr) [^ ]* (?<log>.*)$/ time_format %Y-%m-%dT%H:%M:%S.%N%:z </pattern> </parse> </source> 複製程式碼
細心的你會發現掛載的容器目錄是
/var/lib/docker/containers
,日誌應該都在這裡,但是配置的監聽的目錄卻是/var/log/containers
。官方貼心的給出了註釋,主要內容如下:# Example # ======= # ... # # The Kubernetes fluentd plugin is used to write the Kubernetes metadata to the log # record & add labels to the log record if properly configured. This enables users # to filter & search logs on any metadata. # For example a Docker container's logs might be in the directory: # # /var/lib/docker/containers/997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b # # and in the file: # # 997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b-json.log # # where 997599971ee6... is the Docker ID of the running container. # The Kubernetes kubelet makes a symbolic link to this file on the host machine # in the /var/log/containers directory which includes the pod name and the Kubernetes # container name: # # synthetic-logger-0.25lps-pod_default_synth-lgr-997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b.log # -> # /var/lib/docker/containers/997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b/997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b-json.log # # The /var/log directory on the host is mapped to the /var/log directory in the container # running this instance of Fluentd and we end up collecting the file: # # /var/log/containers/synthetic-logger-0.25lps-pod_default_synth-lgr-997599971ee6366d4a5920d25b79286ad45ff37a74494f262e3bc98d909d0a7b.log # 複製程式碼
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日誌上傳到elasticsearch
output.conf: |- <match **> @id elasticsearch @type elasticsearch @log_level info type_name _doc include_tag_key true host elasticsearch-logging port 9200 logstash_format true <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 retry_max_interval 30 chunk_limit_size 2M queue_limit_length 8 overflow_action block </buffer> </match> 複製程式碼
這裡注意一下其中的host和port,均是elasticsearch service中定義的,如果修改過需要保持一致。fluentd也支援日誌資料上傳到外部的elasticsearch,也就是前文的elk/efk原生。
附錄
- 架構圖
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下載指令碼檔案 download.sh
for file in es-service es-statefulset fluentd-es-configmap fluentd-es-ds kibana-deployment kibana-service; do curl -o $file.yaml https://raw.githubusercontent.com/kubernetes/kubernetes/master/cluster/addons/fluentd-elasticsearch/$file.yaml; done 複製程式碼
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參考連結: