io.javalin.micrometer.MicrometerPlugin.kt Maven / Gradle / Ivy

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/*
 * Javalin - https://javalin.io
 * Copyright 2020 David Åse
 * Licensed under Apache 2.0: https://github.com/tipsy/javalin/blob/master/LICENSE
 */

package io.javalin.micrometer

import io.javalin.config.JavalinConfig
import io.javalin.http.Context
import io.javalin.http.ExceptionHandler
import io.javalin.http.HandlerType
import io.javalin.http.HttpStatus
import io.javalin.plugin.Plugin
import io.javalin.util.Util.firstOrNull
import io.micrometer.core.instrument.MeterRegistry
import io.micrometer.core.instrument.Metrics
import io.micrometer.core.instrument.Tag
import io.micrometer.core.instrument.Tags
import io.micrometer.core.instrument.binder.http.DefaultHttpJakartaServletRequestTagsProvider
import io.micrometer.core.instrument.binder.jetty.JettyConnectionMetrics
import io.micrometer.core.instrument.binder.jetty.JettyServerThreadPoolMetrics
import io.micrometer.jetty11.TimedHandler
import jakarta.servlet.http.HttpServletRequest
import jakarta.servlet.http.HttpServletResponse
import java.util.function.Consumer

class MicrometerPluginConfig {
    @JvmField var registry: MeterRegistry = Metrics.globalRegistry
    @JvmField var tags: Iterable = Tags.empty()
    @JvmField var tagExceptionName: Boolean = false
    @JvmField var tagRedirectPaths: Boolean = false
    @JvmField var tagNotFoundMappedPaths: Boolean = false
}

/**
 * [MicrometerPlugin] has a private constructor, use
 * [MicrometerPlugin.create] to create a new instance.
 */
class MicrometerPlugin(config: Consumer) : Plugin(config, MicrometerPluginConfig()) {

    companion object {
        private const val EXCEPTION_HEADER = "__micrometer_exception_name"
        @JvmField var exceptionHandler = ExceptionHandler { e: Exception, ctx: Context ->
            val simpleName = e.javaClass.simpleName
            ctx.header(EXCEPTION_HEADER, simpleName.ifBlank { e.javaClass.name })
            ctx.status(HttpStatus.INTERNAL_SERVER_ERROR)
        }
    }

    override fun onStart(config: JavalinConfig) {
        val internalRouter = config.pvt.internalRouter

        if (pluginConfig.tagExceptionName) {
            internalRouter.addHttpExceptionHandler(Exception::class.java, exceptionHandler)
        }

        config.jetty.modifyServer { server ->
            server.insertHandler(TimedHandler(pluginConfig.registry, pluginConfig.tags, object : DefaultHttpJakartaServletRequestTagsProvider() {
                override fun getTags(request: HttpServletRequest, response: HttpServletResponse): Iterable {
                    val exceptionName = if (pluginConfig.tagExceptionName) {
                        response.getHeader(EXCEPTION_HEADER)
                    } else {
                        "Unknown"
                    }
                    val pathInfo = request.pathInfo.removePrefix(config.router.contextPath).prefixIfNot("/")
                    response.setHeader(EXCEPTION_HEADER, null)
                    val handlerType = HandlerType.valueOf(request.method)
                    val uri = internalRouter.findHttpHandlerEntries(handlerType, pathInfo)
                        .map { it.endpoint.path }
                        .map { if (it == "/" || it.isBlank()) "root" else it }
                        .map { if (!pluginConfig.tagRedirectPaths && response.status in 300..399) "REDIRECTION" else it }
                        .map { if (!pluginConfig.tagNotFoundMappedPaths && response.status == 404) "NOT_FOUND" else it }
                        .firstOrNull() ?: "NOT_FOUND"
                    return Tags.concat(
                        super.getTags(request, response),
                        "uri", uri,
                        "exception", exceptionName ?: "None"
                    )
                }
            }))

            JettyServerThreadPoolMetrics(server.threadPool, pluginConfig.tags).bindTo(pluginConfig.registry)
            config.events.serverStarted {
                JettyConnectionMetrics.addToAllConnectors(server, pluginConfig.registry, pluginConfig.tags)
            }
        }
    }

    private fun String.prefixIfNot(prefix: String) = if (this.startsWith(prefix)) this else "$prefix$this"
}