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https://issues.apache.org/jira/browse/KAFKA-7755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16811841#comment-16811841
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Loïc Monney commented on KAFKA-7755:
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@Tim: This is not only specific to Kubernetes, but, as you suggested, this is
affecting all environments where IP addresses of Kafka broker are changed at
some time
> Kubernetes - Kafka clients are resolving DNS entries only one time
> ------------------------------------------------------------------
>
> Key: KAFKA-7755
> URL: https://issues.apache.org/jira/browse/KAFKA-7755
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Affects Versions: 2.1.0
> Environment: Kubernetes
> Reporter: Loïc Monney
> Priority: Blocker
> Fix For: 2.2.0, 2.1.1
>
> Attachments: pom.xml
>
>
> *Introduction*
> Since 2.1.0 Kafka clients are supporting multiple DNS resolved IP addresses
> if the first one fails. This change has been introduced by
> https://issues.apache.org/jira/browse/KAFKA-6863. However this DNS resolution
> is now performed only one time by the clients. This is not a problem if all
> brokers have fixed IP addresses, however this is definitely an issue when
> Kafka brokers are run on top of Kubernetes. Indeed, new Kubernetes pods will
> receive another IP address, so as soon as all brokers will have been
> restarted clients won't be able to reconnect to any broker.
> *Impact*
> Everyone running Kafka 2.1 or later on top of Kubernetes is impacted when a
> rolling restart is performed.
> *Root cause*
> Since https://issues.apache.org/jira/browse/KAFKA-6863 Kafka clients are
> resolving DNS entries only once.
> *Proposed solution*
> In
> [https://github.com/apache/kafka/blob/trunk/clients/src/main/java/org/apache/kafka/clients/ClusterConnectionStates.java#L368]
> Kafka clients should perform the DNS resolution again when all IP addresses
> have been "used" (when _index_ is back to 0)
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