面写过过几篇关于在Kubernetes上运行有状态服务相关的博文:
最近需要在我们的一个Kubernetes集群上部署Redis,因此重新整理,写一下如何在Kubernetes上使用Sateful Set部署Redis。
1.需求和环境
我们的需求是需要部署三节点的Redis主从复制,并部署三个节点的Redis Sentinel实现Redis的高可用。
环境信息如下:
- Kubernetes 1.6.7集群
- Ceph 11.2.0集群
Kubernetes的官方examples中已经给出了一个在k8s集群上部署Redis的例子Reliable, Scalable Redis on Kubernetes, 就是基于Redis主从复制+Sentinel实现的,但是这个例子是以无状态服务形式部署的,如果整个k8s集群重启了,Redis的状态就会丢失,因此不能用于生产环境。 但我们可以参考这个例子,以Satefult Set的形式部署。
我们的线上环境主要使用Ceph的块存储RBD作为Kubernetes的存储卷,这里可以将Redis服务的状态保存在Ceph RBD中。
关于Kubernetes和Ceph的部署可以参考我之前写过的几篇博文,这里不再展开:
2.Storage Classes和Dynamic Storage Provision
Kubernetes 1.6开始Storage Classes和Dynamic Storage Provision已经是稳定可用的了。 StorageClass是Dynamic Storage Provision的基础,k8s的管理员可以定义底层存储平台抽象。 用户通过在PVC(Persistent Volume Claim)中通过名字引用StorageClass,PV(Persistent Volume)将使用StorageClass来动态创建,这样就节省了集群管理员手动创建PV的时间。
2.1 在Ceph中创建存储池Pool
我们需要先在Ceph中创建一个k8s集群专用的Ceph Pool,在创建之前我们先看一下当前Ceph集群中的存储池:
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,
一个Ceph集群可以有多个pool,pool是逻辑上的存储池。不同的pool可以有不一样的数据处理方式,例如replica size, placement groups, crush rules,snapshot等等。 可以看到因为我们这个环境还是用Ceph的RGW作为我们的对象存储,因此除了默认的名称为rbd的pool外,还有很多rgw的pool。
下面创建一个专门给k8s集群专用的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,
- 当前这个ceph集群只有3个osd,所以设置pg_num为128,可参考PLACEMENT GROUPS
2.2 配置k8s Node节点访问Ceph
为了让Kubernetes的Node可以调用rbd,如果Ceph集群和Kubernetes集群不是在相同的机器上,还需要在Kubernetes的Node上安装ceph-common:
yum install -y ceph-common
接下来在Kubernetes上创建ceph-secret,这个Secret将用于Kubernetes集群的StorageClass上。
我们先查看一下ceph集群上的所有用户列表:
ceph auth list
这个命令会列出针对Ceph的每种类型的进程已经创建的不同权限的用户,同时也会列出client.admin用户,这个是Ceph集群的管理员用户。
接下来我们创建一个client.kube用户:
ceph auth get-or-create client.kube [client.kube] key = AQAzcYVZ6sbJLhAA7qCBywM+iPRgAG97FtoXIw==
创建好的client.kube用户用户还没有任何权限,下面给其授权:
ceph auth caps client.kube mon 'allow r' osd 'allow rwx pool=kube' updated caps for client.kube
查看用户和权限信息:
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"
因为Kubernetes的Secret需要Base64编码,下面将这个keyring转换成Base64编码:
ceph auth get-key client.kube | base64 QVFBemNZVlo2c2JKTGhBQTdxQ0J5d00raVBSZ0FHOTdGdG9YSXc9PQ==
接下来创建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集群创建StorageClass
首先检查我们的集群中是否有默认的StorageClass:
kubectl get storageclass No resources found.
我们这里使用的k8s集群是使用ansible部署的Kubernetes 1.6 高可用集群,可以看出我们部署的这个集群并没有创建默认的StorageClass。
我们现在集群中创建默认的Storage Class, storege.yaml文件如下:
--- 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”表示这个StorageClass是集群默认的StorageClass
- provisioner: kubernetes.io/rbd表示这个StorageClass的类型时Ceph RBD
- parameters配置了这个StorageClass使用的Ceph集群以及RBD的相关参数
- monitors是逗号分隔的Ceph Mon节点地址
- adminId指定Ceph client 的ID需要具有能在配置的Ceph RBD Pool中创建镜像的权限。默认值为admin
- adminSecret:adminId的Secret Name,该Secret的type必须是”kubernetes.io/rbd”,该参数是必须的
- adminSecretNamespace: adminSecret的namespace,默认为”default”
- pool: Ceph RBD Pool,默认为”rbd”
- userId: Ceph client Id,用来映射RBD镜像。
- userSecretName: userId在映射RBD镜像时所需要的Secret的名称。该Secret要求必须出现在和PVC相同的namespace内,并且type必须是”kubernetes.io/rbd”。该参数是必须的
创建这个默认的StorageClass:
kubectl create -f storage.yaml storageclass "default" created kubectl get storageclass NAME TYPE default (default) kubernetes.io/rbd
- (default)表示这个名称为default的StorageClass是k8s集群默认的StorageClass
3.构建Redis的Docker镜像
参考Reliable, Scalable Redis on Kubernetes中的Redis镜像,我们的Redis的Dockerfile定制如下:
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是我们的基础镜像,在alpine:3.6的基础上增加了glibc,并将时区设置为Asia/Shanghai
参考Reliable, Scalable Redis on Kubernetes中的run.sh做如下定制,原来的run.sh不支持对redis设置密码,加上从环境变量$REDIS_PASS读取redis密码:
#!/bin/bash # Copyright 2014 The Kubernetes Authors. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. function launchmaster() { if [[ ! -e /redis-master-data ]]; then echo "Redis master data doesn't exist, data won't be persistent!" mkdir /redis-master-data fi sed -i "s/%redis-pass%/${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
- 这个脚本根据环境变量MASTER, SENTINEL来判断是启动不同类型的redis进程,如果MASTER为true,则启动redis master,否则如果SENTINEL为true则启动redis sentinel,否则启动redis salve
- 从环境变量REDIS_PASS中读取并设置redis的密码
redis-master.conf的配置文件内容如下:
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配置文件内容如下:
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
构建redis镜像并推送到我们的私有仓库:
docker build -t harbor.frognew.com/rg/redis:1.0 . docker push harbor.frognew.com/rg/rg/redis
4.在Kubernetes集群上部署Redis
假设我们的redis要部署在devops这个namespace下,先在这个namespace下创建ceph-secret-user这个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
- 通过设置环境变量MASTER为true,表明以master形式启动redis,而环境变量REDIS_PASS从devopssecret这个Secret中获取的值,这里略过devopssecret这个Secret的内容
- volumeClaimTemplates中定义了PVC,因为没有给定storageClassName,所以将使用我们前面创建的默认的StorageClass,会根据PVC动态创建StatefulSet中Pod所需的PV
4.2 redis-sentinel.statefulset.yaml
redis-sentinel.statefulset.yaml定义了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的启动逻辑可以查看Docker镜像中的run.sh中launchsentinel()的逻辑
4.5 redis.statefulset.yaml
redis.statefulset.yaml定义了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中定义了PVC,因为没有给定storageClassName,所以将使用我们前面创建的默认的StorageClass,会根据PVC动态创建StatefulSet中Pod所需的PV。
4.4 以StatefulSet的形式部署Redis
下面实际操作一遍基于StatefulSet的Redis的部署。
先创建redis-master的Service和StatefulSet:
kubectl create -f redis-master.statefulset.yaml service "redis-master" created statefulset "redis-master" created
确保这redis master Pod处于running状态:
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
下面创建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
查看StatefulSet确保DESIRED和CURRENT的数量是相同的。
kubectl get statefulset -n devops NAME DESIRED CURRENT AGE redis-master 1 1 3m redis-sentinel 3 3 42s
查看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
下面创建redis slave的Service和StatefulSet:
kubectl create -f redis.statefulset.yaml service "redis" created statefulset "redis" created
注意上面的过程中,在创建redis master和slave的stateful set时可能需要一定的时间,因为涉及到PVC, PV, rbd image的创建,耐心等待。
因为redis-master这个StatefulSet的副本数为1,redis slave这个SatefulSet中的副本数为2,所以我们可以看到集群中创建了3个PVC,并创建了3个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
一定要确认STATUS的状态为Bound,如果不是可以通过kubectl describe pvc <pvc-name> -n <namespace>查看具体的事件。实际上rbd image的创建是由controller-manager调用rbd命令完成的,所以如果有问题也可以看一下controller-manager的日志。
下面的decribe pv命令详细打印出了这个PV已经使用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集群中查看创建的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
我们重点来看一下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为None,这是由有状态服务的特征决定的。 有状态服务具有以下特征:
- 要求有稳定的网络身份,即唯一不变的hostname,并保存在DNS中。hostname是由statefulset的名字后边跟随”-序号”组成,这里是redis-1, redis-2。 同时每个Pod的网络身份也是通过Service定义被创建出来了,根据Service的定义,通过ClusterIp:None指定,该Service将在DNS生成一条没有ClusterIP的记录。
- 要求有持久稳定的存储,通过PVC和PV提供。这里使用了Kubernetes的通过Dynamic Storage Provision特性,PV使用StorageClass来动态创建。
- redis-0,redis-1这两个是reddis的slave节点。
最后我们来看一下k8s集群中redis节点:
kubectl get statefulset -n devops NAME DESIRED CURRENT AGE redis 2 2 8m redis-master 1 1 12m redis-sentinel 3 3 10m
我们以StatefulSet的形式部署了1个master, 2个slave, 3个sentinel。当其中master节点发生故障时,sentinel会从剩余redis节点中选举新的master并切换。 3个redis节点的数据都是保存在ceph rbd中。
k8s 目前不同node 之间使用网段不同,如果一个node上服务停止了,在其他node 上无法使用原ip地址启动的
有状态服务之前叫PetSet,宠物也就是要好好照顾,不能随便调度到不同的node上。实际上使用StatefulSet部署的是有状态集群服务,高可用可以由有状态服务自身的集群保证
StatefulSet不是可以保证master的数量和状态吗,当前master有问题了会重启一个新的master,还有必要使用sentinel吗?
StatefulSet是保证Pod的吧?不太懂。
不知道各位同学有没有部署成功,我怎么没看到 REDIS_SENTINEL_SERVICE_HOST 这个环境变量在哪里定义的
如何在k8s外部访问redis master节点呢,如果定义一个NodePort service,开始是ok的,但是重启master pod之后,service不能关联到redis sentinel选举出来的新的master节点了…如果直接通过redis sentinel返回的master和slave地址的话,这个地址又是容器,pod的地址,在k8s外是无法访问的啊。请问一下有人有好的办法不?
如何在k8s外部访问redis master节点呢,如果定义一个NodePort service,开始是ok的,但是重启master pod之后,service不能关联到redis sentinel选举出来的新的master节点了…如果直接通过redis sentinel返回的master和slave地址的话,这个地址又是容器,pod的地址,在k8s外是无法访问的啊。请问一下有人有好的办法不?