Kibana service giving "FATAL Error: [config validation of [server].host]: value must be a valid hostname (see RFC 1123)" error

Elastic Stack Kibana
1

On the VM where we have installed Elasticsearch and Kibana service, Kibana service is giving "FATAL Error: [config validation of [server].host]: value must be a valid hostname (see RFC 1123)" error. After troubleshooting we found that, VM host name is started with integer. e.g. 123-VM-01 and we have given it to server.host in kibana.yml file.

After changing host name to starting with alphabet e.g. A123-VM-01 then Kibana service started sucessfully. Strangly Elasticsearch service worked with integer host name.

I tried multiple combination of host name and found out that Kibana service gives above error where host name is started with integer. But as per RFC 1123 mentioned in the error, host name starting with integer is valid.

Is it right to say that host name starting with integer is not valid for Kibana service?

2

Run a minimal docker command to start Kibana on a server with a hostname starting with a number and got the same error

docker run --rm --name 1kibana -e SERVER_HOST=1kibana \
  docker.elastic.co/kibana/kibana:8.12.0

Kibana is currently running with legacy OpenSSL providers enabled! For details and instructions on how to disable see https://www.elastic.co/guide/en/kibana/8.12/production.html#openssl-legacy-provider
{"log.level":"info","@timestamp":"2024-02-01T14:31:09.235Z","log.logger":"elastic-apm-node","ecs.version":"8.10.0","agentVersion":"4.2.0","env":{"pid":7,"proctitle":"/usr/share/kibana/bin/../node/bin/node","os":"linux 6.1.0-1029-oem","arch":"x64","host":"277d918d5177","timezone":"UTC+00","runtime":"Node.js v18.18.2"},"config":{"active":{"source":"start","value":true},"breakdownMetrics":{"source":"start","value":false},"captureBody":{"source":"start","value":"off","commonName":"capture_body"},"captureHeaders":{"source":"start","value":false},"centralConfig":{"source":"start","value":false},"contextPropagationOnly":{"source":"start","value":true},"environment":{"source":"start","value":"production"},"globalLabels":{"source":"start","value":[["git_rev","b4a0b5001fc923c868e6b9e1b6e004d280488d49"]],"sourceValue":{"git_rev":"b4a0b5001fc923c868e6b9e1b6e004d280488d49"}},"logLevel":{"source":"default","value":"info","commonName":"log_level"},"metricsInterval":{"source":"start","value":120,"sourceValue":"120s"},"serverUrl":{"source":"start","value":"https://kibana-cloud-apm.apm.us-east-1.aws.found.io/","commonName":"server_url"},"transactionSampleRate":{"source":"start","value":0.1,"commonName":"transaction_sample_rate"},"captureSpanStackTraces":{"source":"start","sourceValue":false},"secretToken":{"source":"start","value":"[REDACTED]","commonName":"secret_token"},"serviceName":{"source":"start","value":"kibana","commonName":"service_name"},"serviceVersion":{"source":"start","value":"8.12.1-SNAPSHOT","commonName":"service_version"}},"activationMethod":"require","message":"Elastic APM Node.js Agent v4.2.0"}
[2024-02-01T14:31:09.897+00:00][INFO ][root] Kibana is starting
[2024-02-01T14:31:09.930+00:00][INFO ][root] Kibana is shutting down
[2024-02-01T14:31:09.933+00:00][FATAL][root] Reason: [config validation of [server].host]: value must be a valid hostname (see RFC 1123).
Error: [config validation of [server].host]: value must be a valid hostname (see RFC 1123).
    at ObjectType.validate (/usr/share/kibana/node_modules/@kbn/config-schema/src/types/type.js:94:13)
    at ConfigService.validateAtPath (/usr/share/kibana/node_modules/@kbn/config/src/config_service.js:253:19)
    at /usr/share/kibana/node_modules/@kbn/config/src/config_service.js:263:204
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/map.js:10:37
    at OperatorSubscriber._this._next (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/OperatorSubscriber.js:33:21)
    at OperatorSubscriber.Subscriber.next (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Subscriber.js:51:18)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/distinctUntilChanged.js:18:28
    at OperatorSubscriber._this._next (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/OperatorSubscriber.js:33:21)
    at OperatorSubscriber.Subscriber.next (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Subscriber.js:51:18)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/map.js:10:24
    at OperatorSubscriber._this._next (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/OperatorSubscriber.js:33:21)
    at OperatorSubscriber.Subscriber.next (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Subscriber.js:51:18)
    at ReplaySubject._subscribe (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/ReplaySubject.js:54:24)
    at ReplaySubject.Observable._trySubscribe (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:41:25)
    at ReplaySubject.Subject._trySubscribe (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Subject.js:123:47)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:35:31
    at Object.errorContext (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/errorContext.js:22:9)
    at ReplaySubject.Observable.subscribe (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:26:24)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/share.js:66:18
    at OperatorSubscriber.<anonymous> (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/lift.js:14:28)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:30:30
    at Object.errorContext (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/errorContext.js:22:9)
    at Observable.subscribe (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:26:24)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/map.js:9:16
    at OperatorSubscriber.<anonymous> (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/lift.js:14:28)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:30:30
    at Object.errorContext (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/errorContext.js:22:9)
    at Observable.subscribe (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:26:24)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/distinctUntilChanged.js:13:16
    at OperatorSubscriber.<anonymous> (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/lift.js:14:28)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:30:30
    at Object.errorContext (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/errorContext.js:22:9)
    at Observable.subscribe (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:26:24)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/operators/map.js:9:16
    at SafeSubscriber.<anonymous> (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/lift.js:14:28)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:30:30
    at Object.errorContext (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/util/errorContext.js:22:9)
    at Observable.subscribe (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/Observable.js:26:24)
    at /usr/share/kibana/node_modules/rxjs/dist/cjs/internal/firstValueFrom.js:24:16
    at new Promise (<anonymous>)
    at firstValueFrom (/usr/share/kibana/node_modules/rxjs/dist/cjs/internal/firstValueFrom.js:8:12)
    at EnvironmentService.preboot (/usr/share/kibana/node_modules/@kbn/core-environment-server-internal/src/environment_service.js:50:169)
    at Server.preboot (/usr/share/kibana/node_modules/@kbn/core-root-server-internal/src/server.js:146:55)
    at Root.preboot (/usr/share/kibana/node_modules/@kbn/core-root-server-internal/src/root/index.js:47:32)
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at bootstrap (/usr/share/kibana/node_modules/@kbn/core-root-server-internal/src/bootstrap.js:97:9)
    at Command.<anonymous> (/usr/share/kibana/src/cli/serve/serve.js:241:5)

 FATAL  Error: [config validation of [server].host]: value must be a valid hostname (see RFC 1123).

I've opened an issue about this for my colleagues to review

3

Thank you for opening an issue.

I have modified hostname to start with alphabet for time being as it was in production.

4

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