ERROR: epmd error for host rabbitmq-server-2.rabbitmq-nodes.default: nxdomain (non-existing domain)

[khteh]

Hit the following error during RabbitmqCluster container startup:

[rabbitmq-server-1 rabbitmq] 2026-05-23 05:32:31.300569+00:00 [error] <0.144.0> BOOT FAILED
[rabbitmq-server-1 rabbitmq] 2026-05-23 05:32:31.300569+00:00 [error] <0.144.0> ===========
[rabbitmq-server-1 rabbitmq] 2026-05-23 05:32:31.300569+00:00 [error] <0.144.0> ERROR: epmd error for host rabbitmq-server-1.rabbitmq-nodes.default: nxdomain (non-existing domain)
[rabbitmq-server-1 rabbitmq] 2026-05-23 05:32:31.300569+00:00 [error] <0.144.0> 
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>     supervisor: {local,rabbit_prelaunch_sup}
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>     errorContext: start_error
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>     reason: {epmd_error,"rabbitmq-server-2.rabbitmq-nodes.default",nxdomain}
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>     offender: [{pid,undefined},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>                {id,prelaunch},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>                {mfargs,{rabbit_prelaunch,run_prelaunch_first_phase,[]}},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>                {restart_type,transient},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>                {significant,false},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>                {shutdown,5000},
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>     supervisor: {local,rabbit_prelaunch_sup}
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0>                {child_type,worker}]
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>     errorContext: start_error
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627078+00:00 [error] <0.144.0> 
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>     reason: {epmd_error,"rabbitmq-server-0.rabbitmq-nodes.default",nxdomain}
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>     offender: [{pid,undefined},
[rabbitmq-server-2 rabbitmq] {exit,terminating,[{application_controller,call,2,[{file,"application_controller.erl"},{line,511}]},{application,'-ensure_all_started/3-lc$^0/1-0-',1,[{file,"application.erl"},{line,367}]},{application,ensure_all_started,3,[{file,"application.erl"},{line,367}]},{rabbit,'-start_it/1-fun-0-',1,[{file,"rabbit.erl"},{line,442}]},{timer,tc,2,[{file,"timer.erl"},{line,595}]},{rabbit,start_it,1,[{file,"rabbit.erl"},{line,440}]},{init,start_it,1,[]},{init,start_em,1,[]}]}
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627358+00:00 [notice] <0.45.0> Application rabbitmq_prelaunch exited with reason: {{shutdown,{failed_to_start_child,prelaunch,{epmd_error,"rabbitmq-server-2.rabbitmq-nodes.default",nxdomain}}},{rabbit_prelaunch_app,start,[normal,[]]}}
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>                {id,prelaunch},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>   crasher:
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>                {mfargs,{rabbit_prelaunch,run_prelaunch_first_phase,[]}},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     initial call: application_master:init/3
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>                {restart_type,transient},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     pid: <0.142.0>
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>                {significant,false},
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>                {shutdown,5000},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     registered_name: []
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     exception exit: {{shutdown,
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0>                {child_type,worker}]
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.647873+00:00 [error] <0.144.0> 
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>                          {failed_to_start_child,prelaunch,
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>                              {epmd_error,
[rabbitmq-server-0 rabbitmq] {exit,terminating,[{application_controller,call,2,[{file,"application_controller.erl"},{line,511}]},{application,'-ensure_all_started/3-lc$^0/1-0-',1,[{file,"application.erl"},{line,367}]},{application,ensure_all_started,3,[{file,"application.erl"},{line,367}]},{rabbit,'-start_it/1-fun-0-',1,[{file,"rabbit.erl"},{line,442}]},{timer,tc,2,[{file,"timer.erl"},{line,595}]},{rabbit,start_it,1,[{file,"rabbit.erl"},{line,440}]},{init,start_it,1,[]},{init,start_em,1,[]}]}
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>                                  "rabbitmq-server-2.rabbitmq-nodes.default",
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648209+00:00 [notice] <0.45.0> Application rabbitmq_prelaunch exited with reason: {{shutdown,{failed_to_start_child,prelaunch,{epmd_error,"rabbitmq-server-0.rabbitmq-nodes.default",nxdomain}}},{rabbit_prelaunch_app,start,[normal,[]]}}
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>                                  nxdomain}}},
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>   crasher:
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>                      {rabbit_prelaunch_app,start,[normal,[]]}}
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     initial call: application_master:init/3
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>       in function  application_master:init/3 (application_master.erl, line 143)
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     pid: <0.142.0>
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     registered_name: []
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     ancestors: [application_controller,<0.10.0>]
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     message_queue_len: 1
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     exception exit: {{shutdown,
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>                          {failed_to_start_child,prelaunch,
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     messages: [{'EXIT',<0.143.0>,normal}]
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>                              {epmd_error,
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     links: [<0.45.0>]
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>                                  "rabbitmq-server-0.rabbitmq-nodes.default",
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     dictionary: []
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>                                  nxdomain}}},
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     trap_exit: true
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>                      {rabbit_prelaunch_app,start,[normal,[]]}}
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     status: running
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>       in function  application_master:init/3 (application_master.erl, line 143)
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     heap_size: 376
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     stack_size: 29
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     ancestors: [application_controller,<0.10.0>]
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>     reductions: 77
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     message_queue_len: 1
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     messages: [{'EXIT',<0.143.0>,normal}]
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0>   neighbours:
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     links: [<0.45.0>]
[rabbitmq-server-2 rabbitmq] 2026-05-23 05:32:31.627501+00:00 [error] <0.142.0> 
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     dictionary: []
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     trap_exit: true
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     status: running
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     heap_size: 376
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     stack_size: 29
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>     reductions: 77
[rabbitmq-server-0 rabbitmq] 2026-05-23 05:32:31.648483+00:00 [error] <0.142.0>   neighbours:

This causes the pod startup probe failure:

  Warning  Unhealthy  23s  kubelet  spec.containers{rabbitmq}: Startup probe failed: Error: unable to perform an operation on node 'rabbit@rabbitmq-server-0.rabbitmq-nodes.default'. Please see diagnostics information and suggestions below.

[michaelklishin]

@khteh please stop using this repository's issues as a general support forum. At the very least consider using GitHub Discussions.

nxdomain us UNIX speak for "the hostname cannot be resolved". This image is not responsible for hostname resolution. As the docs explain, RabbitMQ nodes must be able to resolve their own hostnames or they won't be able to form a cluster or even start. This is exactly what happens in your case, an nxdomain exception very early on node boot.

The Cluster Formation guide touches on this topic in the context of Kubernetes, and even links to some relevant Kubernetes docs.

[khteh]

In most cases you don't need to worry about peer discovery, when deploying to Kubernetes.

Cluster Operator (the recommended way of deploying to Kubernetes) as well as popular Helm charts, pre-configure peer discovery for you.

[khteh]

It's not DNS problem:

$ kubectl exec -it ubuntu -- nslookup rabbitmq-server-2.rabbitmq-nodes.default.svc.cluster.local
;; Got recursion not available from 10.152.183.10
Server:		10.152.183.10
Address:	10.152.183.10#53

Name:	rabbitmq-server-2.rabbitmq-nodes.default.svc.cluster.local
Address: 10.1.207.234
;; Got recursion not available from 10.152.183.10

[michaelklishin]

Yes, it is. nxdomain is a very specific error code. The node cannot resolve its own hostname.