在Kubernetes中使用Sateful Set部署Redis_Kubernetes中文社群
面寫過過幾篇關於在Kubernetes上執行有狀態服務相關的博文:
最近需要在我們的一個Kubernetes叢集上部署Redis,因此重新整理,寫一下如何在Kubernetes上使用Sateful Set部署Redis。
1.需求和環境
我們的需求是需要部署三節點的Redis主從複製,並部署三個節點的Redis Sentinel實現Redis的高可用。
環境資訊如下:
- Kubernetes 1.6.7叢集
- Ceph 11.2.0叢集
Kubernetes的官方examples中已經給出了一個在k8s叢集上部署Redis的例子Reliable, Scalable Redis on Kubernetes
我們的線上環境主要使用Ceph的塊儲存RBD作為Kubernetes的儲存卷,這裡可以將Redis服務的狀態儲存在Ceph RBD中。
關於Kubernetes和Ceph的部署可以參考我之前寫過的幾篇博文,這裡不再展開:
2.Storage Classes和Dynamic Storage Provision
Kubernetes 1.6開始Storage Classes和Dynamic Storage Provision已經是穩定可用的了。 StorageClass是Dynamic Storage Provision的基礎,k8s的管理員可以定義底層儲存平臺抽象。 使用者通過在PVC(Persistent Volume Claim)中通過名字引用StorageClass,PV(Persistent Volume)將使用StorageClass來動態建立,這樣就節省了叢集管理員手動建立PV的時間。
2.1 在Ceph中建立儲存池Pool
我們需要先在Ceph中建立一個k8s叢集專用的Ceph Pool,在建立之前我們先看一下當前Ceph叢集中的儲存池:
ceph osd lspools 0 rbd,1 .rgw.root,2 default.rgw.control,3 default.rgw.data.root,4 default.rgw.gc,5 default.rgw.lc,6 default.rgw.log,7 default.rgw.users.uid,8 default.rgw.users.email,9 default.rgw.users.keys,10 default.rgw.buckets.index,11 default.rgw.buckets.data,
一個Ceph叢集可以有多個pool,pool是邏輯上的儲存池。不同的pool可以有不一樣的資料處理方式,例如replica size, placement groups, crush rules,snapshot等等。 可以看到因為我們這個環境還是用Ceph的RGW作為我們的物件儲存,因此除了預設的名稱為rbd的pool外,還有很多rgw的pool。
下面建立一個專門給k8s叢集專用的pool kube:
ceph osd pool create kube 128 pool 'kube' created ceph osd lspools 0 rbd,1 .rgw.root,2 default.rgw.control,3 default.rgw.data.root,4 default.rgw.gc,5 default.rgw.lc,6 default.rgw.log,7 default.rgw.users.uid,8 default.rgw.users.email,9 default.rgw.users.keys,10 default.rgw.buckets.index,11 default.rgw.buckets.data,12 kube,
- 當前這個ceph叢集只有3個osd,所以設定pg_num為128,可參考PLACEMENT GROUPS
2.2 配置k8s Node節點訪問Ceph
為了讓Kubernetes的Node可以呼叫rbd,如果Ceph叢集和Kubernetes叢集不是在相同的機器上,還需要在Kubernetes的Node上安裝ceph-common:
yum install -y ceph-common
接下來在Kubernetes上建立ceph-secret,這個Secret將用於Kubernetes叢集的StorageClass上。
我們先檢視一下ceph叢集上的所有使用者列表:
ceph auth list
這個命令會列出針對Ceph的每種型別的程序已經建立的不同許可權的使用者,同時也會列出client.admin使用者,這個是Ceph叢集的管理員使用者。
接下來我們建立一個client.kube使用者:
ceph auth get-or-create client.kube [client.kube] key = AQAzcYVZ6sbJLhAA7qCBywM+iPRgAG97FtoXIw==
建立好的client.kube使用者使用者還沒有任何許可權,下面給其授權:
ceph auth caps client.kube mon 'allow r' osd 'allow rwx pool=kube' updated caps for client.kube
檢視使用者和許可權資訊:
ceph auth get client.kube exported keyring for client.kube [client.kube] key = AQAzcYVZ6sbJLhAA7qCBywM+iPRgAG97FtoXIw== caps mon = "allow r" caps osd = "allow rwx pool=kube"
因為Kubernetes的Secret需要Base64編碼,下面將這個keyring轉換成Base64編碼:
ceph auth get-key client.kube | base64 QVFBemNZVlo2c2JKTGhBQTdxQ0J5d00raVBSZ0FHOTdGdG9YSXc9PQ==
接下來建立Secret,ceph-secret.yaml:
apiVersion: v1 kind: Secret metadata: name: ceph-secret namespace: kube-system type: kubernetes.io/rbd data: key: QVFBemNZVlo2c2JKTGhBQTdxQ0J5d00raVBSZ0FHOTdGdG9YSXc9PQ==
kubectl create -f ceph-secret.yaml secret "ceph-secret" created
2.3 在k8s叢集建立StorageClass
首先檢查我們的叢集中是否有預設的StorageClass:
kubectl get storageclass No resources found.
我們這裡使用的k8s叢集是使用ansible部署的Kubernetes 1.6 高可用叢集,可以看出我們部署的這個叢集並沒有建立預設的StorageClass。
我們現在叢集中建立預設的Storage Class, storege.yaml檔案如下:
--- apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: name: default annotations: storageclass.kubernetes.io/is-default-class: "true" labels: kubernetes.io/cluster-service: "true" provisioner: kubernetes.io/rbd parameters: monitors: 192.168.61.3:6789,192.168.61.4:6789,192.168.61.5:6789 adminId: kube adminSecretName: ceph-secret adminSecretNamespace: kube-system pool: kube userId: kube userSecretName: ceph-secret-user
- annotations中storageclass.kubernetes.io/is-default-class: “true”表示這個StorageClass是叢集預設的StorageClass
- provisioner: kubernetes.io/rbd表示這個StorageClass的型別時Ceph RBD
- parameters配置了這個StorageClass使用的Ceph叢集以及RBD的相關引數
- monitors是逗號分隔的Ceph Mon節點地址
- adminId指定Ceph client 的ID需要具有能在配置的Ceph RBD Pool中建立映象的許可權。預設值為admin
- adminSecret:adminId的Secret Name,該Secret的type必須是”kubernetes.io/rbd”,該引數是必須的
- adminSecretNamespace: adminSecret的namespace,預設為”default”
- pool: Ceph RBD Pool,預設為”rbd”
- userId: Ceph client Id,用來對映RBD映象。
- userSecretName: userId在對映RBD映象時所需要的Secret的名稱。該Secret要求必須出現在和PVC相同的namespace內,並且type必須是”kubernetes.io/rbd”。該引數是必須的
建立這個預設的StorageClass:
kubectl create -f storage.yaml storageclass "default" created kubectl get storageclass NAME TYPE default (default) kubernetes.io/rbd
- (default)表示這個名稱為default的StorageClass是k8s叢集預設的StorageClass
3.構建Redis的Docker映象
FROM harbor.frognew.com/rg/alpine-glibc:0.1 RUN apk add --no-cache redis sed bash COPY redis-master.conf /redis-master/redis.conf COPY redis-slave.conf /redis-slave/redis.conf COPY run.sh /run.sh RUN chmod u+x /run.sh CMD [ "/run.sh" ] ENTRYPOINT [ "bash", "-c" ]
- alpine-glibc:0.1是我們的基礎映象,在alpine:3.6的基礎上增加了glibc,並將時區設定為Asia/Shanghai
參考Reliable, Scalable Redis on Kubernetes中的run.sh做如下定製,原來的run.sh不支援對redis設定密碼,加上從環境變數$REDIS_PASS讀取redis密碼:
#!/bin/bash # Copyright 2014 The Kubernetes Authors. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. function launchmaster() { if [[ ! -e /redis-master-data ]]; then echo "Redis master data doesn't exist, data won't be persistent!" mkdir /redis-master-data fi sed -i "s/%redis-pass%/${REDIS_PASS}/" /redis-master/redis.conf redis-server /redis-master/redis.conf --protected-mode no } function launchsentinel() { while true; do master=$(redis-cli -a $REDIS_PASS -h ${REDIS_SENTINEL_SERVICE_HOST} -p ${REDIS_SENTINEL_SERVICE_PORT} --csv SENTINEL get-master-addr-by-name mymaster | tr ',' ' ' | cut -d' ' -f1) if [[ -n ${master} ]]; then master="${master//\"}" else master=${REDIS_MASTER_SERVICE_HOST} fi redis-cli -a $REDIS_PASS -h ${master} INFO if [[ "$?" == "0" ]]; then break fi echo "Connecting to master failed. Waiting..." sleep 10 done sentinel_conf=sentinel.conf echo "sentinel monitor mymaster ${master} 6379 2" > ${sentinel_conf} echo "sentinel auth-pass mymaster ${REDIS_PASS}" >> ${sentinel_conf} echo "sentinel down-after-milliseconds mymaster 60000" >> ${sentinel_conf} echo "sentinel failover-timeout mymaster 180000" >> ${sentinel_conf} echo "sentinel parallel-syncs mymaster 1" >> ${sentinel_conf} echo "bind 0.0.0.0" >> ${sentinel_conf} redis-sentinel ${sentinel_conf} --protected-mode no } function launchslave() { while true; do master=$(redis-cli -a $REDIS_PASS -h ${REDIS_SENTINEL_SERVICE_HOST} -p ${REDIS_SENTINEL_SERVICE_PORT} --csv SENTINEL get-master-addr-by-name mymaster | tr ',' ' ' | cut -d' ' -f1) if [[ -n ${master} ]]; then master="${master//\"}" else echo "Failed to find master." sleep 60 exit 1 fi redis-cli -a $REDIS_PASS -h ${master} INFO if [[ "$?" == "0" ]]; then break fi echo "Connecting to master failed. Waiting..." sleep 10 done sed -i "s/%master-ip%/${master}/" /redis-slave/redis.conf sed -i "s/%master-port%/6379/" /redis-slave/redis.conf sed -i "s/%redis-pass%/${REDIS_PASS}/" /redis-slave/redis.conf redis-server /redis-slave/redis.conf --protected-mode no } if [[ "${MASTER}" == "true" ]]; then launchmaster exit 0 fi if [[ "${SENTINEL}" == "true" ]]; then launchsentinel exit 0 fi launchslave
- 這個指令碼根據環境變數MASTER, SENTINEL來判斷是啟動不同型別的redis程序,如果MASTER為true,則啟動redis master,否則如果SENTINEL為true則啟動redis sentinel,否則啟動redis salve
- 從環境變數REDIS_PASS中讀取並設定redis的密碼
redis-master.conf的配置檔案內容如下:
daemonize no pidfile /var/run/redis.pid port 6379 tcp-backlog 511 bind 0.0.0.0 timeout 0 tcp-keepalive 60 loglevel notice logfile "" databases 16 save 900 1 save 300 10 save 60 10000 stop-writes-on-bgsave-error yes rdbcompression yes rdbchecksum yes dbfilename dump.rdb dir /redis-master-data slave-serve-stale-data yes rename-command FLUSHALL "" rename-command FLUSHDB "" slave-read-only yes repl-diskless-sync no repl-diskless-sync-delay 5 repl-disable-tcp-nodelay no slave-priority 100 requirepass %redis-pass% appendonly yes appendfilename "appendonly.aof" appendfsync everysec no-appendfsync-on-rewrite no auto-aof-rewrite-percentage 100 auto-aof-rewrite-min-size 64mb aof-load-truncated yes lua-time-limit 5000 slowlog-log-slower-than 10000 slowlog-max-len 128 latency-monitor-threshold 0 notify-keyspace-events "" hash-max-ziplist-entries 512 hash-max-ziplist-value 64 list-max-ziplist-entries 512 list-max-ziplist-value 64 set-max-intset-entries 512 zset-max-ziplist-entries 128 zset-max-ziplist-value 64 hll-sparse-max-bytes 3000 activerehashing yes client-output-buffer-limit normal 0 0 0 client-output-buffer-limit slave 256mb 64mb 60 client-output-buffer-limit pubsub 32mb 8mb 60 hz 10 aof-rewrite-incremental-fsync yes
redis-slave.conf配置檔案內容如下:
daemonize no pidfile /var/run/redis.pid port 6379 tcp-backlog 511 bind 0.0.0.0 timeout 0 tcp-keepalive 60 loglevel notice logfile "" databases 16 save 900 1 save 300 10 save 60 10000 stop-writes-on-bgsave-error yes rdbcompression yes rdbchecksum yes dbfilename dump.rdb dir "/data" slaveof %master-ip% %master-port% masterauth %redis-pass% slave-serve-stale-data yes rename-command FLUSHALL "" rename-command FLUSHDB "" slave-read-only yes repl-diskless-sync no repl-diskless-sync-delay 5 repl-disable-tcp-nodelay no slave-priority 100 requirepass %redis-pass% appendonly yes appendfilename "appendonly.aof" appendfsync everysec no-appendfsync-on-rewrite no auto-aof-rewrite-percentage 100 auto-aof-rewrite-min-size 64mb aof-load-truncated yes lua-time-limit 5000 slowlog-log-slower-than 10000 slowlog-max-len 128 latency-monitor-threshold 0 notify-keyspace-events "" hash-max-ziplist-entries 512 hash-max-ziplist-value 64 list-max-ziplist-entries 512 list-max-ziplist-value 64 set-max-intset-entries 512 zset-max-ziplist-entries 128 zset-max-ziplist-value 64 hll-sparse-max-bytes 3000 activerehashing yes client-output-buffer-limit normal 0 0 0 client-output-buffer-limit slave 256mb 64mb 60 client-output-buffer-limit pubsub 32mb 8mb 60 hz 10 aof-rewrite-incremental-fsync yes
構建redis映象並推送到我們的私有倉庫:
docker build -t harbor.frognew.com/rg/redis:1.0 . docker push harbor.frognew.com/rg/rg/redis
4.在Kubernetes叢集上部署Redis
假設我們的redis要部署在devops這個namespace下,先在這個namespace下建立ceph-secret-user這個Secret:
apiVersion: v1 kind: Secret metadata: name: ceph-secret-user namespace: devops type: kubernetes.io/rbd data: key: QVFBemNZVlo2c2JKTGhBQTdxQ0J5d00raVBSZ0FHOTdGdG9YSXc9PQ==
kubectl crate -f ceph-secret-user.yaml
4.1 redis-master.statefulset.yaml
redis-master.statefulset.yaml是redis master的Service和StatefulSet。
apiVersion: v1 kind: Service metadata: name: redis-master namespace: devops labels: name: redis-master spec: ports: - port: 6379 selector: redis-master: "true" --- apiVersion: apps/v1beta1 kind: StatefulSet metadata: name: redis-master namespace: devops labels: name: redis-master spec: serviceName: redis-master replicas: 1 template: metadata: labels: app: redis-master redis-master: "true" spec: terminationGracePeriodSeconds: 10 containers: - name: redis image: harbor.frognew.com/rg/redis:1.0 imagePullPolicy: IfNotPresent ports: - containerPort: 6379 env: - name: MASTER value: "true" - name: REDIS_PASS valueFrom: secretKeyRef: name: devopssecret key: redisAuthPass resources: requests: memory: "256Mi" cpu: "250m" limits: memory: "512Mi" cpu: "500m" volumeMounts: - name: redis-master-volume mountPath: /data imagePullSecrets: - name: regsecret volumeClaimTemplates: - metadata: name: redis-master-volume spec: accessModes: [ "ReadWriteOnce" ] resources: requests: storage: 5Gi
- 通過設定環境變數MASTER為true,表明以master形式啟動redis,而環境變數REDIS_PASS從devopssecret這個Secret中獲取的值,這裡略過devopssecret這個Secret的內容
- volumeClaimTemplates中定義了PVC,因為沒有給定storageClassName,所以將使用我們前面建立的預設的StorageClass,會根據PVC動態建立StatefulSet中Pod所需的PV
4.2 redis-sentinel.statefulset.yaml
redis-sentinel.statefulset.yaml定義了redis-sentinel的Service和StatefulSet:
apiVersion: v1 kind: Service metadata: name: redis-sentinel namespace: devops labels: name: redis-sentinel spec: ports: - port: 26379 targetPort: 26379 selector: redis-sentinel: "true" --- apiVersion: apps/v1beta1 kind: StatefulSet metadata: name: redis-sentinel namespace: devops spec: serviceName: redis-sentinel replicas: 3 template: metadata: labels: redis-sentinel: "true" spec: terminationGracePeriodSeconds: 10 containers: - name: redis-sentinel image: harbor.frognew.com/rg/redis:1.0 imagePullPolicy: IfNotPresent ports: - containerPort: 26379 name: redis-sentinel env: - name: SENTINEL value: "true" - name: REDIS_PASS valueFrom: secretKeyRef: name: devopssecret key: redisAuthPass imagePullSecrets: - name: regsecret
- sentinel的啟動邏輯可以檢視Docker映象中的run.sh中launchsentinel()的邏輯
4.5 redis.statefulset.yaml
redis.statefulset.yaml定義了redis slave的Service和SatefulSet:
apiVersion: v1 kind: Service metadata: name: redis namespace: devops labels: app: redis spec: ports: - port: 6379 clusterIP: None selector: app: redis --- apiVersion: apps/v1beta1 kind: StatefulSet metadata: name: redis namespace: devops labels: name: redis spec: serviceName: redis replicas: 2 template: metadata: labels: app: redis spec: terminationGracePeriodSeconds: 10 containers: - name: redis image: harbor.frognew.com/rg/redis:1.0 imagePullPolicy: IfNotPresent ports: - containerPort: 6379 env: - name: REDIS_PASS valueFrom: secretKeyRef: name: devopssecret key: redisAuthPass resources: requests: memory: "256Mi" cpu: "250m" limits: memory: "512Mi" cpu: "500m" volumeMounts: - name: redis-volume mountPath: /data imagePullSecrets: - name: regsecret volumeClaimTemplates: - metadata: name: redis-volume spec: accessModes: [ "ReadWriteOnce" ] resources: requests: storage: 5Gi
- volumeClaimTemplates中定義了PVC,因為沒有給定storageClassName,所以將使用我們前面建立的預設的StorageClass,會根據PVC動態建立StatefulSet中Pod所需的PV。
4.4 以StatefulSet的形式部署Redis
下面實際操作一遍基於StatefulSet的Redis的部署。
先建立redis-master的Service和StatefulSet:
kubectl create -f redis-master.statefulset.yaml service "redis-master" created statefulset "redis-master" created
確保這redis master Pod處於running狀態:
kubectl get pods -l redis-master="true" -n devops NAME READY STATUS RESTARTS AGE redis-master-0 1/1 Running 0 48s kubectl get svc -l name="redis-master" -n devops NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE redis-master 10.104.132.220 <none> 6379/TCP 1m
下面建立redis-sentinel的Service和StatefulSet:
kubectl create -f redis-sentinel.statefulset.yaml service "redis-sentinel" created statefulset "redis-sentinel" created kubectl get svc -l name="redis-sentinel" -n devops -o wide NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR redis-sentinel 10.97.4.9 <none> 26379/TCP 16s redis-sentinel=true
檢視StatefulSet確保DESIRED和CURRENT的數量是相同的。
kubectl get statefulset -n devops NAME DESIRED CURRENT AGE redis-master 1 1 3m redis-sentinel 3 3 42s
檢視sentinel Pod:
kubectl get pod -l redis-sentinel="true" -n devops NAME READY STATUS RESTARTS AGE redis-sentinel-0 1/1 Running 0 1m redis-sentinel-1 1/1 Running 0 1m redis-sentinel-2 1/1 Running 0 1m
下面建立redis slave的Service和StatefulSet:
kubectl create -f redis.statefulset.yaml service "redis" created statefulset "redis" created
注意上面的過程中,在建立redis master和slave的stateful set時可能需要一定的時間,因為涉及到PVC, PV, rbd image的建立,耐心等待。
因為redis-master這個StatefulSet的副本數為1,redis slave這個SatefulSet中的副本數為2,所以我們可以看到叢集中建立了3個PVC,並建立了3個PV:
kubectl get pvc -n devops NAME STATUS VOLUME CAPACITY ACCESSMODES STORAGECLASS AGE redis-master-volume-redis-master-0 Bound pvc-fd2c30e3-7b14-11e7-ad4a-1866da8c6175 5Gi RWO default 10m redis-volume-redis-0 Bound pvc-65a2ba2c-7b17-11e7-ad4a-1866da8c6175 5Gi RWO default 7m redis-volume-redis-1 Bound pvc-6a96951c-7b17-11e7-ad4a-1866da8c6175 5Gi RWO default 7m kubectl get pv -n devops NAME CAPACITY ACCESSMODES RECLAIMPOLICY STATUS CLAIM STORAGECLASS REASON AGE pvc-65a2ba2c-7b17-11e7-ad4a-1866da8c6175 5Gi RWO Delete Bound devops/redis-volume-redis-0 default 10m pvc-6a96951c-7b17-11e7-ad4a-1866da8c6175 5Gi RWO Delete Bound devops/redis-volume-redis-1 default 7m pvc-fd2c30e3-7b14-11e7-ad4a-1866da8c6175 5Gi RWO Delete Bound devops/redis-master-volume-redis-master-0 default 7m
一定要確認STATUS的狀態為Bound,如果不是可以通過kubectl describe pvc <pvc-name> -n <namespace>檢視具體的事件。實際上rbd image的建立是由controller-manager呼叫rbd命令完成的,所以如果有問題也可以看一下controller-manager的日誌。
下面的decribe pv命令詳細打印出了這個PV已經使用Ceph RBD Image:
kubectl describe pv pvc-65a2ba2c-7b17-11e7-ad4a-1866da8c6175 -n devops Name: pvc-65a2ba2c-7b17-11e7-ad4a-1866da8c6175 Labels: <none> Annotations: pv.kubernetes.io/bound-by-controller=yes pv.kubernetes.io/provisioned-by=kubernetes.io/rbd StorageClass: default Status: Bound Claim: devops/redis-volume-redis-0 Reclaim Policy: Delete Access Modes: RWO Capacity: 5Gi Message: Source: Type: RBD (a Rados Block Device mount on the host that shares a pod's lifetime) CephMonitors: [192.168.61.3:6789 192.168.61.4:6879 192.168.61.5:6789] RBDImage: kubernetes-dynamic-pvc-856cff45-7a7b-11e7-ac3c-1866da8c2fcd FSType: RBDPool: kube RadosUser: kube Keyring: /etc/ceph/keyring SecretRef: &{ceph-secret-user} ReadOnly: false Events: <none>
另外可以在Ceph叢集中檢視建立的rbd image:
rbd list kube kubernetes-dynamic-pvc-856cff45-7a7b-11e7-ac3c-1866da8c2fcd kubernetes-dynamic-pvc-8b1be6fc-7a7b-11e7-ac3c-1866da8c2fcd kubernetes-dynamic-pvc-cce6429c-7a7a-11e7-ac3c-1866da8c2fcd rbd info -p kube --image kubernetes-dynamic-pvc-856cff45-7a7b-11e7-ac3c-1866da8c2fcd rbd image 'kubernetes-dynamic-pvc-856cff45-7a7b-11e7-ac3c-1866da8c2fcd': size 5120 MB in 1280 objects order 22 (4096 kB objects) block_name_prefix: rb.0.3e17b.238e1f29 format: 1
kubectl get statefulset -n devops NAME DESIRED CURRENT AGE redis 2 2 5m redis-master 1 1 10m redis-sentinel 3 3 7m
我們重點來看一下redis statefulset和redis service:
kubectl get svc -l app="redis" -n devops NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE redis None <none> 6379/TCP 7m kubectl get pod -l app="redis" -n devops NAME READY STATUS RESTARTS AGE redis-0 1/1 Running 0 7m redis-1 1/1 Running 0 7m
注意redis service的CLUSTER-IP為None,這是由有狀態服務的特徵決定的。 有狀態服務具有以下特徵:
- 要求有穩定的網路身份,即唯一不變的hostname,並儲存在DNS中。hostname是由statefulset的名字後邊跟隨”-序號”組成,這裡是redis-1, redis-2。 同時每個Pod的網路身份也是通過Service定義被創建出來了,根據Service的定義,通過ClusterIp:None指定,該Service將在DNS生成一條沒有ClusterIP的記錄。
- 要求有持久穩定的儲存,通過PVC和PV提供。這裡使用了Kubernetes的通過Dynamic Storage Provision特性,PV使用StorageClass來動態建立。
- redis-0,redis-1這兩個是reddis的slave節點。
最後我們來看一下k8s叢集中redis節點:
kubectl get statefulset -n devops NAME DESIRED CURRENT AGE redis 2 2 8m redis-master 1 1 12m redis-sentinel 3 3 10m
我們以StatefulSet的形式部署了1個master, 2個slave, 3個sentinel。當其中master節點發生故障時,sentinel會從剩餘redis節點中選舉新的master並切換。 3個redis節點的資料都是儲存在ceph rbd中。