一.kafka介绍
kafka是一个分布式、多副本、多订阅者、分区的，基于zoopkeeper协调的分布式日志系统。其主要特点为：
1.以时间复杂度为O(1)的方式提供消息持久化能力，即使对TB级以上的数据也能保证常数时间的访问性能。
2.高吞吐率。即使在非常廉价的商用机器上也能做到单机支持每秒100K消息的传输。
3.支持kafka server间的消息分区以及分布式消费，同时保证每个partition内的消息顺序和传输。
4.同时支持离线数据处理和实时数据处理。
二.应用场景
1.日志收集
2.数据推送
3.作为大缓冲区使用
4.服务中间件
三.应用架构
如上图所示，一个kafka集群包含若干个Producer(服务器日志、业务数据、Web前端产生的page view等)，若干个Broker(kafka支持水平扩展，一般broker数量越多，集群的吞吐量越大)，若干个consumer group，一个zookeeper集群(kafka通过zookeeper管理集群配置、选举leader、consumer group等发生变化时进行rebalance)。
3.1 名词解释
-
broker
消息中间件处理节点(服务器)，一个节点就是一个broker，一个kafka集群由一个或多个broker组成 -
Topic
kafka对消息进行归类，发送到集群的每一条消息都要指定一个topic -
Partition
物理上的概念，每个topic包含一个或多个partition，一个partition对应一个文件夹，这个文件夹下存储partition的数据和索引文件，每个partition内部是有序的。 -
Producer
生产者，负责发布消息到broker -
Consumer
消费者，从broker读取消息 -
ConsumerGroup
每个consumer属于一个特定的consumer group，可为每个consumer指定group name，若不指定，则属于默认的group，一条消息可以发送到不同的consumer group，但一个consumer group中只能有一个consumer能消费这条消息。
四.kubernetes集群部署kafka
4.1 部署前准备
- 创建好的至少三个节点的kubernetes集群(这里我们使用的版本1.13.10)
- 创建好的存储类StorageClass(这里我们使用的是cephfs)
4.2 部署yaml文件
1.部署zookeeper的yaml文件
[root@k8s001 kafka]# cat zookeeper.yaml
apiVersion: v1
kind: Service
metadata:
name: zk-hs
namespace: kafka
labels:
app: zk
spec:
ports:
- port: 2888
name: server
- port: 3888
name: leader-election
clusterIP: None
selector:
app: zk
---
apiVersion: v1
kind: Service
metadata:
name: zk-cs
namespace: kafka
labels:
app: zk
spec:
ports:
- port: 2181
name: client
selector:
app: zk
---
apiVersion: policy/v1beta1
kind: PodDisruptionBudget
metadata:
name: zk-pdb
namespace: kafka
spec:
selector:
matchLabels:
app: zk
maxUnavailable: 1
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: zk
namespace: kafka
spec:
selector:
matchLabels:
app: zk
serviceName: zk-hs
replicas: 3
updateStrategy:
type: RollingUpdate
podManagementPolicy: Parallel
template:
metadata:
labels:
app: zk
spec:
nodeSelector:
travis.io/schedule-only: "kafka"
tolerations:
- key: "travis.io/schedule-only"
operator: "Equal"
value: "kafka"
effect: "NoSchedule"
- key: "travis.io/schedule-only"
operator: "Equal"
value: "kafka"
effect: "NoExecute"
tolerationSeconds: 3600
- key: "travis.io/schedule-only"
operator: "Equal"
value: "kafka"
effect: "PreferNoSchedule"
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: "app"
operator: In
values:
- zk
topologyKey: "kubernetes.io/hostname"
containers:
- name: kubernetes-zookeeper
imagePullPolicy: IfNotPresent
image: fastop/zookeeper:3.4.10
resources:
requests:
memory: "200Mi"
cpu: "0.1"
ports:
- containerPort: 2181
name: client
- containerPort: 2888
name: server
- containerPort: 3888
name: leader-election
command:
- sh
- -c
- "start-zookeeper
--servers=3
--data_dir=/var/lib/zookeeper/data
--data_log_dir=/var/lib/zookeeper/data/log
--conf_dir=/opt/zookeeper/conf
--client_port=2181
--election_port=3888
--server_port=2888
--tick_time=2000
--init_limit=10
--sync_limit=5
--heap=512M
--max_client_cnxns=60
--snap_retain_count=3
--purge_interval=12
--max_session_timeout=40000
--min_session_timeout=4000
--log_level=INFO"
readinessProbe:
exec:
command:
- sh
- -c
- "zookeeper-ready 2181"
initialDelaySeconds: 10
timeoutSeconds: 5
livenessProbe:
exec:
command:
- sh
- -c
- "zookeeper-ready 2181"
initialDelaySeconds: 10
timeoutSeconds: 5
volumeMounts:
- name: datadir
mountPath: /var/lib/zookeeper
# 这里我们需要将runAsuser和fsGroup用户调整为0，也就是管理员用户允许，否则会提示权限的报错
securityContext:
runAsUser: 0
fsGroup: 0
volumeClaimTemplates:
- metadata:
name: datadir
spec:
accessModes: [ "ReadWriteMany" ]
storageClassName: cephfs
resources:
requests:
storage: 20Gi
2.部署kafka的yaml文件
[root@k8s001 kafka]# cat kafka.yaml
---
apiVersion: v1
kind: Service
metadata:
name: kafka-svc
namespace: kafka
labels:
app: kafka
spec:
ports:
- port: 9092
name: server
clusterIP: None
selector:
app: kafka
---
apiVersion: policy/v1beta1
kind: PodDisruptionBudget
metadata:
name: kafka-pdb
namespace: kafka
spec:
selector:
matchLabels:
app: kafka
minAvailable: 2
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: kafka
namespace: kafka
spec:
selector:
matchLabels:
app: kafka
serviceName: kafka-svc
replicas: 3
template:
metadata:
labels:
app: kafka
spec:
nodeSelector:
travis.io/schedule-only: "kafka"
tolerations:
- key: "travis.io/schedule-only"
operator: "Equal"
value: "kafka"
effect: "NoSchedule"
- key: "travis.io/schedule-only"
operator: "Equal"
value: "kafka"
effect: "NoExecute"
tolerationSeconds: 3600
- key: "travis.io/schedule-only"
operator: "Equal"
value: "kafka"
effect: "PreferNoSchedule"
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: "app"
operator: In
values:
- kafka
topologyKey: "kubernetes.io/hostname"
podAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 1
podAffinityTerm:
labelSelector:
matchExpressions:
- key: "app"
operator: In
values:
- zk
topologyKey: "kubernetes.io/hostname"
terminationGracePeriodSeconds: 300
containers:
- name: k8s-kafka
imagePullPolicy: IfNotPresent
image: fastop/kafka:2.2.0
resources:
requests:
memory: "600Mi"
cpu: 500m
ports:
- containerPort: 9092
name: server
command:
- sh
- -c
- "exec kafka-server-start.sh /opt/kafka/config/server.properties --override broker.id=${HOSTNAME##*-}
--override listeners=PLAINTEXT://:9092
--override zookeeper.connect=zk-0.zk-hs.kafka.svc.cluster.local:2181,zk-1.zk-hs.kafka.svc.cluster.local:2181,zk-2.zk-hs.kafka.svc.cluster.local:2181
--override log.dir=/var/lib/kafka
--override auto.create.topics.enable=true
--override auto.leader.rebalance.enable=true
--override background.threads=10
--override compression.type=producer
--override delete.topic.enable=false
--override leader.imbalance.check.interval.seconds=300
--override leader.imbalance.per.broker.percentage=10
--override log.flush.interval.messages=9223372036854775807
--override log.flush.offset.checkpoint.interval.ms=60000
--override log.flush.scheduler.interval.ms=9223372036854775807
--override log.retention.bytes=-1
--override log.retention.hours=168
--override log.roll.hours=168
--override log.roll.jitter.hours=0
--override log.segment.bytes=1073741824
--override log.segment.delete.delay.ms=60000
--override message.max.bytes=1000012
--override min.insync.replicas=1
--override num.io.threads=8
--override num.network.threads=3
--override num.recovery.threads.per.data.dir=1
--override num.replica.fetchers=1
--override offset.metadata.max.bytes=4096
--override offsets.commit.required.acks=-1
--override offsets.commit.timeout.ms=5000
--override offsets.load.buffer.size=5242880
--override offsets.retention.check.interval.ms=600000
--override offsets.retention.minutes=1440
--override offsets.topic.compression.codec=0
--override offsets.topic.num.partitions=50
--override offsets.topic.replication.factor=3
--override offsets.topic.segment.bytes=104857600
--override queued.max.requests=500
--override quota.consumer.default=9223372036854775807
--override quota.producer.default=9223372036854775807
--override replica.fetch.min.bytes=1
--override replica.fetch.wait.max.ms=500
--override replica.high.watermark.checkpoint.interval.ms=5000
--override replica.lag.time.max.ms=10000
--override replica.socket.receive.buffer.bytes=65536
--override replica.socket.timeout.ms=30000
--override request.timeout.ms=30000
--override socket.receive.buffer.bytes=102400
--override socket.request.max.bytes=104857600
--override socket.send.buffer.bytes=102400
--override unclean.leader.election.enable=true
--override zookeeper.session.timeout.ms=6000
--override zookeeper.set.acl=false
--override broker.id.generation.enable=true
--override connections.max.idle.ms=600000
--override controlled.shutdown.enable=true
--override controlled.shutdown.max.retries=3
--override controlled.shutdown.retry.backoff.ms=5000
--override controller.socket.timeout.ms=30000
--override default.replication.factor=1
--override fetch.purgatory.purge.interval.requests=1000
--override group.max.session.timeout.ms=300000
--override group.min.session.timeout.ms=6000
--override inter.broker.protocol.version=2.2.0
--override log.cleaner.backoff.ms=15000
--override log.cleaner.dedupe.buffer.size=134217728
--override log.cleaner.delete.retention.ms=86400000
--override log.cleaner.enable=true
--override log.cleaner.io.buffer.load.factor=0.9
--override log.cleaner.io.buffer.size=524288
--override log.cleaner.io.max.bytes.per.second=1.7976931348623157E308
--override log.cleaner.min.cleanable.ratio=0.5
--override log.cleaner.min.compaction.lag.ms=0
--override log.cleaner.threads=1
--override log.cleanup.policy=delete
--override log.index.interval.bytes=4096
--override log.index.size.max.bytes=10485760
--override log.message.timestamp.difference.max.ms=9223372036854775807
--override log.message.timestamp.type=CreateTime
--override log.preallocate=false
--override log.retention.check.interval.ms=300000
--override max.connections.per.ip=2147483647
--override num.partitions=4
--override producer.purgatory.purge.interval.requests=1000
--override replica.fetch.backoff.ms=1000
--override replica.fetch.max.bytes=1048576
--override replica.fetch.response.max.bytes=10485760
--override reserved.broker.max.id=1000 "
env:
- name: KAFKA_HEAP_OPTS
value : "-Xmx512M -Xms512M"
- name: KAFKA_OPTS
value: "-Dlogging.level=INFO"
volumeMounts:
- name: datadir
mountPath: /var/lib/kafka
readinessProbe:
tcpSocket:
port: 9092
timeoutSeconds: 1
initialDelaySeconds: 5
securityContext:
runAsUser: 1000
fsGroup: 1000
volumeClaimTemplates:
- metadata:
name: datadir
spec:
accessModes: [ "ReadWriteMany" ]
storageClassName: cephfs
resources:
requests:
storage: 20Gi
4.3 部署
这里zookeeper和kafka都是有状态的服务，不能使用deployment和rc这种控制器来部署，这里我们使用statefulset来部署zookeeper和kafka服务。
4.3.1 给节点打标签
这里我们想在哪几台机器上来运行kafka，需要对节点进行打标签。
kubectl label node [node-name] travis.io/schedule-only=kafka
当然，如果我们如果不想在哪些节点运行kafka，可以通过配置污点来进行。
kubectl taint node [node-name] travis.io/schedule-only=kafka:NoSchedule
4.3.2 创建命名空间
[root@k8s001 kafka]# kubectl create ns kafka
4.3.3 创建zookeeper服务
# 创建zookeeper服务
[root@k8s001 kafka]# kubectl apply -f zookeeper.yaml
# 查看zookeeper服务运行状态
[root@k8s001 kafka]# kubectl get pod -n kafka
NAME READY STATUS RESTARTS AGE
zk-0 1/1 Running 0 7m8s
zk-1 1/1 Running 0 7m8s
zk-2 1/1 Running 0 7m8s
4.3.4 创建kafka服务
[root@k8s001 kafka]# kubectl apply -f kafka.yaml
[root@k8s001 kafka]# kubectl get pod -n kafka
NAME READY STATUS RESTARTS AGE
kafka-0 1/1 Running 0 11m
kafka-1 1/1 Running 0 11m
kafka-2 1/1 Running 0 10m
zk-0 1/1 Running 0 6m44s
zk-1 1/1 Running 0 6m44s
zk-2 1/1 Running 0 6m44s
4.3.5 测试
测试zookeeper：
kubectl exec -it zk-0 -n kafka -- zkServer.sh status
kubectl exec -it zk-0 -n kafka -- zkCli.sh create /hello world
kubectl delete -f zookeeper.yaml
kubectl apply -f zookeeper.yaml
kubectl exec -it zk-0 -n kafka -- zkCli.sh get /hello
测试kafka:
kubectl exec -it kafka-0 -n kafka -- bash
>kafka-topics.sh --create
--topic test
--zookeeper zk-0.zk-hs.kafka.svc.cluster.local:2181,zk-1.zk-hs.kafka.svc.cluster.local:2181,zk-2.zk-hs.kafka.svc.cluster.local:2181
--partitions 3
--replication-factor 2
kafka-topics.sh --list --zookeeper zk-0.zk-hs.kafka.svc.cluster.local:2181,zk-1.zk-hs.kafka.svc.cluster.local:2181,zk-2.zk-hs.kafka.svc.cluster.local:2181
kafka-console-consumer.sh --topic test --bootstrap-server localhost:9092
# 另起一个窗口，进入kafka-1容器
kubectl exec -it kafka-1 -n kafka -- bash
>kafka-console-producer.sh --topic test --broker-list localhost:9092
随便输入内容，观察kafka-0启动的kafka-console-consumer.sh的输出。