override fun install()

in ktor-features/ktor-metrics-micrometer/jvm/src/io/ktor/metrics/micrometer/MicrometerMetrics.kt [172:217]
38 lines of code
3 McCabe index (conditional complexity)

        override fun install(pipeline: Application, configure: Configuration.() -> Unit): MicrometerMetrics {
            val configuration = Configuration().apply(configure)

            if (!configuration.isRegistryInitialized()) {
                throw IllegalArgumentException(
                    "Meter registry is missing. Please initialize the field 'registry'"
                )
            }

            val feature = MicrometerMetrics(
                configuration.registry,
                configuration.distributionStatisticConfig,
                configuration.timerBuilder
            )

            configuration.meterBinders.forEach { it.bindTo(configuration.registry) }

            val phase = PipelinePhase("MicrometerMetrics")
            pipeline.insertPhaseBefore(ApplicationCallPipeline.Monitoring, phase)

            pipeline.intercept(phase) {
                feature.before(call)
                try {
                    proceed()
                } catch (e: Throwable) {
                    feature.throwable(call, e)
                    throw e
                }
            }

            val postSendPhase = PipelinePhase("MicrometerMetricsPostSend")
            pipeline.sendPipeline.insertPhaseAfter(ApplicationSendPipeline.After, postSendPhase)
            pipeline.sendPipeline.intercept(ApplicationSendPipeline.After) {
                try {
                    proceed()
                } finally {
                    feature.after(call)
                }
            }

            pipeline.environment.monitor.subscribe(Routing.RoutingCallStarted) { call ->
                call.attributes[measureKey].route = call.route.parent.toString()
            }

            return feature
        }