expose health check API through REST API

[zzzz465]

I'm trying to expose the broker using AWS NLB. the NLB has health-check mechanism, and TCP or HTTP (or others) are used.

if I use TCP for checking, it tries to connect to TCP port (6650 default). it works but also leaves error message that makes hard to read pulsar's log messages.
I can use HTTP /metrics/ API for checking, but it is not a valid way to do a health check.

so, I'd like to access to health check API through REST API same as pulsar CLI.
I've searched wiki and discussions and I cannot find any similar things so far.

below is the log that I consistently have everytime when AWS NLB tries to health check.

2023-06-29T03:03:41,989+0000 [pulsar-io-4-3] WARN  org.apache.pulsar.broker.service.ServerCnx - [/10.31.107.110:59743] Got exception io.netty.handler.codec.TooLongFrameException: Adjusted frame length exceeds 5253120: 218762510 - discarded
        at io.netty.handler.codec.LengthFieldBasedFrameDecoder.fail(LengthFieldBasedFrameDecoder.java:507)
        at io.netty.handler.codec.LengthFieldBasedFrameDecoder.failIfNecessary(LengthFieldBasedFrameDecoder.java:493)
        at io.netty.handler.codec.LengthFieldBasedFrameDecoder.exceededFrameLength(LengthFieldBasedFrameDecoder.java:377)
        at io.netty.handler.codec.LengthFieldBasedFrameDecoder.decode(LengthFieldBasedFrameDecoder.java:423)
        at io.netty.handler.codec.LengthFieldBasedFrameDecoder.decode(LengthFieldBasedFrameDecoder.java:333)
        at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:529)
        at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:468)
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:290)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
        at io.netty.handler.flush.FlushConsolidationHandler.channelRead(FlushConsolidationHandler.java:152)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
        at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:800)
        at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:499)
        at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:397)
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
        at java.base/java.lang.Thread.run(Thread.java:833)