Hi Pulsar Community, This is a PIP discussion on how support custom DNSes configuration to be used by the Pulsar Client.
This is the PIP issue https://github.com/apache/pulsar/pull/21352 # Motivation Currently Pulsar client levereage on JVM detected DNSes or on Google DNSes if nothing was found (as per Netty default). You cannot change which DNSes use to resolve hostnames but you are forced to use local server one (like DNSes configured through resolv.conf or similar ways) or leverage on some Netty "black magic" system properties. The ability to directly configure which DNSes use is strictly necessary in environment with "specialized" DNSes. # Goals ## In Scope Add a new configuration on Pulsar client to explicitly set which DNSes use. ## Out of Scope Fully configure DNS layer, properties, timeouts etcetera. # High Level Design A new client configuration will be added to list wich DNSes use. Such configuration will be checked when creating Pulsar clients to instantiate the DNS resolver. If no configuration is provided the client must use current defaults. # Detailed Design ## Design & Implementation Details The new configuration will be read from org.apache.pulsar.client.impl.ConnectionPool to configure a DnsNameResolverBuilder ## Public-facing Changes Add new dnsServerAddresses method on org.apache.pulsar.client.api.ClientBuilder. There are no breaking changes, if dnsServerAddresses is not configuret Pulsar will continue to behave like now. ### Public API NA ### Binary protocol NA ### Configuration Add new dnsServerAddresses property on org.apache.pulsar.client.impl.conf.ClientConfigurationData. ### CLI NA ### Metrics NA # Monitoring NA # Security Considerations The client will have the ability to use a different seto of DNSes. It is possible to alter hostnames resolutions however it is expected that this does not pose any security risks. # Backward & Forward Compatibility ## Revert Just remove dnsServerAddresses configuration ## Upgrade Configure a dnsServerAddresses server list. The configuration is not mandatory, Pulsar can run without it just like before. # Alternatives Expose an interface builder to fully configure the DNS layer. It has much more impact and conflict with existing configuration properties dnsLookupBindAddress and dnsLookupBindPort. Diego Salvi
