DNS resolution failures on cached peer names tanks casper.

[nashef]

What did you expect to see?

DNS failures are handled gracefully.

What did you see instead?

2026-01-13 18:35:37,420 [grpc-default-executor-0] WARN  io.grpc.internal.ManagedChannelImpl - [Channel<34>: (rnode.readonly:40400)] Failed to resolve name. status=Status{code=UNAVAILABLE, description=Unable to resolve host rnode.readonly, cause=java.lang.RuntimeException: java.net.UnknownHostException: rnode.readonly: Name or service not known
        at io.grpc.internal.DnsNameResolver.resolveAddresses(DnsNameResolver.java:223)
        at io.grpc.internal.DnsNameResolver.doResolve(DnsNameResolver.java:282)
        at io.grpc.internal.DnsNameResolver$Resolve.run(DnsNameResolver.java:318)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.net.UnknownHostException: rnode.readonly: Name or service not known
        at java.base/java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
        at java.base/java.net.InetAddress$PlatformNameService.lookupAllHostAddr(InetAddress.java:934)
        at java.base/java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1543)
        at java.base/java.net.InetAddress$NameServiceAddresses.get(InetAddress.java:852)
        at java.base/java.net.InetAddress.getAllByName0(InetAddress.java:1533)
        at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1385)
        at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1306)
        at io.grpc.internal.DnsNameResolver$JdkAddressResolver.resolveAddress(DnsNameResolver.java:631)
        at io.grpc.internal.DnsNameResolver.resolveAddresses(DnsNameResolver.java:219)
        ... 5 more
}
2026-01-13 18:47:41,491 [node-runner-726] WARN  coop.rchain.casper.api.BlockAPI$ - Could not visualize graph, casper instance was not available yet.
2026-01-13 18:47:48,168 [node-runner-697] WARN  coop.rchain.casper.api.BlockAPI$ - Could not visualize graph, casper instance was not available yet.

Steps to reproduce the bug

Run the shard with shardctl, then run docker stop rnode.readonly.

What version of RNode are you using?

main branch.

[linear]

F1R-119

[nashef]

The issue is that the gRPC client persists when connections are cleared, but when the docker container goes away, the mdns name is removed and DNS lookups fail.