Logtash to Logstash native communication output host issue

[dobl1]

Logstash information:

Logstash 8.11.1 docker image (in docker compose)
docker.elastic.co/logstash/logstash:8.11.1

Description of the problem:

Trying the Logtash to Logstash native communication

With a simple output

output {
    stdout {}
    logstash {
        hosts => "logstash:9800"
        ssl_enabled => false
        username => "user"
        password => "secret"
    }
}

Logs:

2023-11-22 00:39:17 [2023-11-21T23:39:17,065][ERROR][logstash.outputs.logstash] Invalid setting for logstash output plugin:
2023-11-22 00:39:17 
2023-11-22 00:39:17   output {
2023-11-22 00:39:17     logstash {
2023-11-22 00:39:17       # This setting must be a required_host_optional_port
2023-11-22 00:39:17       # Expected a valid required-host optional-port pair, got `"logstash:9800"`
2023-11-22 00:39:17       hosts => "logstash:9800"
2023-11-22 00:39:17       ...
2023-11-22 00:39:17     }
2023-11-22 00:39:17   }
2023-11-22 00:39:17 [2023-11-21T23:39:17,074][ERROR][logstash.agent           ] Failed to execute action {:action=>LogStash::PipelineAction::Create/pipeline_id:main, :exception=>"Java::JavaLang::IllegalStateException", :message=>"Unable to configure plugins: (ConfigurationError) Something is wrong with your configuration.", :backtrace=>["org.logstash.config.ir.CompiledPipeline.<init>(CompiledPipeline.java:120)", "org.logstash.execution.AbstractPipelineExt.initialize(AbstractPipelineExt.java:186)", "org.logstash.execution.AbstractPipelineExt$INVOKER$i$initialize.call(AbstractPipelineExt$INVOKER$i$initialize.gen)", "org.jruby.internal.runtime.methods.JavaMethod$JavaMethodN.call(JavaMethod.java:847)", "org.jruby.ir.runtime.IRRuntimeHelpers.instanceSuper(IRRuntimeHelpers.java:1318)", "org.jruby.ir.instructions.InstanceSuperInstr.interpret(InstanceSuperInstr.java:139)", "org.jruby.ir.interpreter.InterpreterEngine.processCall(InterpreterEngine.java:367)", "org.jruby.ir.interpreter.StartupInterpreterEngine.interpret(StartupInterpreterEngine.java:66)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.INTERPRET_METHOD(MixedModeIRMethod.java:128)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.call(MixedModeIRMethod.java:115)", "org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:90)", "org.jruby.RubyClass.newInstance(RubyClass.java:931)", "org.jruby.RubyClass$INVOKER$i$newInstance.call(RubyClass$INVOKER$i$newInstance.gen)", "org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:90)", "org.jruby.ir.instructions.CallBase.interpret(CallBase.java:561)", "org.jruby.ir.interpreter.InterpreterEngine.processCall(InterpreterEngine.java:367)", "org.jruby.ir.interpreter.StartupInterpreterEngine.interpret(StartupInterpreterEngine.java:66)", "org.jruby.ir.interpreter.InterpreterEngine.interpret(InterpreterEngine.java:88)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.INTERPRET_METHOD(MixedModeIRMethod.java:238)", "org.jruby.internal.runtime.methods.MixedModeIRMethod.call(MixedModeIRMethod.java:225)", "org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:228)", "org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:291)", "org.jruby.ir.interpreter.InterpreterEngine.processCall(InterpreterEngine.java:328)", "org.jruby.ir.interpreter.StartupInterpreterEngine.interpret(StartupInterpreterEngine.java:66)", "org.jruby.ir.interpreter.Interpreter.INTERPRET_BLOCK(Interpreter.java:116)", "org.jruby.runtime.MixedModeIRBlockBody.commonYieldPath(MixedModeIRBlockBody.java:136)", "org.jruby.runtime.IRBlockBody.call(IRBlockBody.java:66)", "org.jruby.runtime.IRBlockBody.call(IRBlockBody.java:58)", "org.jruby.runtime.Block.call(Block.java:143)", "org.jruby.RubyProc.call(RubyProc.java:352)", "org.jruby.internal.runtime.RubyRunnable.run(RubyRunnable.java:110)", "java.base/java.lang.Thread.run(Thread.java:840)"]}

I don't understand why this configuration is invalid, it's a simple host:port, like in the doc, can you help please ?

[mashhurs]

Our current host validator expects host to be in logstash.host (two parts with . separated) style (like top-level domains). This case seems also valid like localhost and we may consider it in the future.

[jsvd]

Running a bin/logstash-plugin update will update existing plugins and also grab the 1.1.1 version of the "logstash-mixin-validator_support" gem that fixes the issue of not supporting single word hostnames, like "localhost".