如何在Kubernetes中对外公开StatefulSet的无头服务 [英] How to expose a headless service for a StatefulSet externally in Kubernetes

问题描述

使用 kubernetes-kafka 作为minikube的起点.

Using kubernetes-kafka as a starting point with minikube.

这使用StatefulSet和无头服务进行服务在集群中发现.

This uses a StatefulSet and a headless service for service discovery within the cluster.

目标是在外部公开各个Kafka经纪人，这些经纪人内部地址为:

The goal is to expose the individual Kafka Brokers externally which are internally addressed as:

kafka-0.broker.kafka.svc.cluster.local:9092
kafka-1.broker.kafka.svc.cluster.local:9092 
kafka-2.broker.kafka.svc.cluster.local:9092

约束是该外部服务能够专门针对经纪人.

The constraint is that this external service be able to address the brokers specifically.

解决此问题的正确方法(或一种可能的方法)是什么?是否可以根据kafka-x.broker.kafka.svc.cluster.local:9092公开外部服务?

Whats the right (or one possible) way of going about this? Is it possible to expose a external service per kafka-x.broker.kafka.svc.cluster.local:9092?

推荐答案

到目前为止，解决方案还不足以让我自己满意，所以我将发表自己的答案.我的目标:

Solutions so far weren't quite satisfying enough for myself, so I'm going to post an answer of my own. My goals:

1. 仍应通过StatefulSet尽可能多地动态管理Pod.
2. 在每个Pod(即Kafka Broker)中为生产者/消费者客户端创建外部服务，并避免负载平衡.
3. 创建内部无头服务，以便每个Broker可以彼此通信.

从 Yolean/kubernetes-kafka 开始，唯一缺少的是在外部公开该服务，这样做有两个挑战.

Starting with Yolean/kubernetes-kafka, the only thing missing is exposing the service externally and two challenges in doing so.

1. 为每个Broker容器生成唯一的标签，以便我们可以为每个Broker容器创建一个外部服务.
2. 在配置Kafka告诉生产者/消费者通过外部服务进行通信的同时，告诉经纪人使用内部服务进行相互通信.

每个吊舱标签和外部服务:

要为每个吊舱生成标签，此问题确实很有帮助.以此为指导，我们将以下行添加到 10broker-config.yml init.sh属性，其中:

To generate labels per pod, this issue was really helpful. Using it as a guide, we add the following line to the 10broker-config.yml init.sh property with:

kubectl label pods ${HOSTNAME} kafka-set-component=${HOSTNAME}

我们保留了现有的无头服务，但是我们还使用标签为每个pod生成了一个外部服务(我将它们添加到

We keep the existing headless service, but we also generate an external Service per pod using the label (I added them to 20dns.yml):

apiVersion: v1
kind: Service
metadata:
  name: broker-0
   namespace: kafka
spec:
  type: NodePort
  ports:
  - port: 9093
    nodePort: 30093
selector:
  kafka-set-component: kafka-0

使用内部/外部监听器配置Kafka

我发现此问题在试图了解如何配置Kafka方面非常有用

I found this issue incredibly useful in trying to understand how to configure Kafka.

这又需要更新 10broker-config.yml ，其中包含以下内容:

This again requires updating the init.sh and server.properties properties in 10broker-config.yml with the following:

在server.properties中添加以下内容以更新安全协议(当前使用PLAINTEXT):

Add the following to the server.properties to update the security protocols (currently using PLAINTEXT):

listener.security.protocol.map=INTERNAL_PLAINTEXT:PLAINTEXT,EXTERNAL_PLAINTEXT:PLAINTEXT
inter.broker.listener.name=INTERNAL_PLAINTEXT

动态确定init.sh中每个Pod的外部IP和外部端口:

Dynamically determine the external IP and for external port for each Pod in the init.sh:

EXTERNAL_LISTENER_IP=<your external addressable cluster ip>
EXTERNAL_LISTENER_PORT=$((30093 + ${HOSTNAME##*-}))

然后为EXTERNAL_LISTENER和INTERNAL_LISTENER(也在init.sh属性中)配置listeners和advertised.listeners IP:

Then configure listeners and advertised.listeners IPs for EXTERNAL_LISTENER and INTERNAL_LISTENER (also in the init.sh property):

sed -i "s/#listeners=PLAINTEXT:\/\/:9092/listeners=INTERNAL_PLAINTEXT:\/\/0.0.0.0:9092,EXTERNAL_PLAINTEXT:\/\/0.0.0.0:9093/" /etc/kafka/server.properties
sed -i "s/#advertised.listeners=PLAINTEXT:\/\/your.host.name:9092/advertised.listeners=INTERNAL_PLAINTEXT:\/\/$HOSTNAME.broker.kafka.svc.cluster.local:9092,EXTERNAL_PLAINTEXT:\/\/$EXTERNAL_LISTENER_IP:$EXTERNAL_LISTENER_PORT/" /etc/kafka/server.properties

很明显，这不是完整的生产解决方案(例如，解决外部暴露的经纪人的安全问题)，并且我仍在加深对如何让内部生产者/消费者也与经纪人进行沟通的理解.

Obviously, this is not a full solution for production (for example addressing security for the externally exposed brokers) and I'm still refining my understanding of how to also let internal producer/consumers to also communicate with the brokers.

但是，到目前为止，这是我了解Kubernetes和Kafka的最佳方法.

However, so far this is the best approach for my understanding of Kubernetes and Kafka.

这篇关于如何在Kubernetes中对外公开StatefulSet的无头服务的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！