GitHub user tisonkun created a discussion: Tips - Workaround incorrect DNS
resolutions on MacOS
I'd like to share my experience of workaround incorrect DNS resolutions on
MacOS for Pulsar standalone.
When you run Pulsar standalone by `bin/pulsar standalone` on MacOS, you should
always see the following warnings:
```
2022-08-11T20:24:10,581+0800 [main] WARN
io.netty.resolver.dns.DnsServerAddressStreamProviders - Can not find
io.netty.resolver.dns.macos.MacOSDnsServerAddressStreamProvider in the
classpath, fallback to system defaults. This may result in incorrect DNS
resolutions on MacOS.
```
This is because we don't bundle the related netty resolver for DNS on MacOS. It
may or may not cause an issue. I meet one issue today:
```
2022-08-11T14:32:22,296+0800 [main] WARN
io.netty.resolver.dns.DnsServerAddressStreamProviders - Can not find
io.netty.resolver.dns.macos.MacOSDnsServerAddressStreamProvider in the
classpath, fallback to system defaults. This may result in incorrect DNS
resolutions on MacOS.
2022-08-11T14:32:24,381+0800 [main] ERROR
org.apache.pulsar.functions.worker.PulsarWorkerService - Error Starting up in
worker
java.lang.ExceptionInInitializerError: null
at
io.netty.resolver.dns.UnixResolverDnsServerAddressStreamProvider.parseSilently(UnixResolverDnsServerAddressStreamProvider.java:80)
~[netty-resolver-dns-4.1.77.Final.jar:4.1.77.Final]
```
This error causes the standalone process to fail and exit.
To workaround the issue, download the necessary libs and add them to the
classpath.
1. Download
[netty-resolver-dns-classes-macos-4.1.77.Final.jar](https://repo1.maven.org/maven2/io/netty/netty-resolver-dns-classes-macos/4.1.77.Final)
and
[netty-resolver-dns-native-macos-4.1.77.Final-osx-aarch_64.jar](https://repo1.maven.org/maven2/io/netty/netty-resolver-dns-native-macos/4.1.77.Final)
(version and arch can be varied on your env).
2. Place these two libs under a chosen folder, said `/path/to/my/libs`.
3. Run Pulsar standalone with env var `PULSAR_EXTRA_CLASSPATH` which allows
adding extra libs:
```sh
PULSAR_EXTRA_CLASSPATH=/path/to/my/libs/* ./bin/pulsar standalone
```
The issue should be resolved atm :D
GitHub link: https://github.com/apache/pulsar/discussions/17067
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