Add OpenTelemetry JVM metrics with Prometheus and Grafana observability stack

[Copilot]

• Removed redundant imports (cats.syntax.flatMap.* and cats.syntax.functor.*)
• Fixed misleading log message placement - now logs right after OpenTelemetry initialization
• Added Grafana provisioning configuration to auto-configure Prometheus datasource
• All tests passing

Original prompt

Add opentelemetry libs to scrape metrics. You can find details by this link https://typelevel.org/otel4s/oteljava/metrics-jvm-runtime.html
Also add prometheus and grafana to the docker-compose file to observe new metrics in real time.

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[trett]

@copilot 1. According the docs there is more simple usage of this library. Try to apply this approach:

import cats.syntax.flatMap._
import cats.syntax.functor._
import io.opentelemetry.api.{OpenTelemetry => JOpenTelemetry}
import io.opentelemetry.instrumentation.runtimemetrics.java17._
import org.typelevel.otel4s.oteljava.OtelJava

object Service extends IOApp.Simple {
  
  def run: IO[Unit] = 
    OtelJava
      .autoConfigured[IO]()
      .flatTap(otel4s => registerRuntimeMetrics(otel4s.underlying))
      .use { otel4s =>
        val _ = otel4s
        ???
      }

  private def registerRuntimeMetrics[F[_]: Sync](
      openTelemetry: JOpenTelemetry
  ): Resource[F, Unit] = {
    val acquire = Sync[F].delay(RuntimeMetrics.create(openTelemetry))

    Resource.fromAutoCloseable(acquire).void
  }
}

2. Also there are newest version of these libraries are available

libraryDependencies ++= Seq(
  "org.typelevel" %% "otel4s-oteljava" % "0.14.0", // <1>
  "io.opentelemetry.instrumentation" % "opentelemetry-runtime-telemetry-java17" % "2.22.0-alpha" // <2>
)

3. Remove too detailed description of changes from the README file.

[Copilot]

@copilot 1. According the docs there is more simple usage of this library. Try to apply this approach:

import cats.syntax.flatMap._...

I've addressed all three points in commit fb960c5:

1. ✅ Simplified implementation using OtelJava.autoConfigured() with RuntimeMetrics.create() as suggested
2. ✅ Updated to latest versions: otel4s 0.14.0 and runtime-telemetry 2.22.0-alpha
3. ✅ Simplified README by removing detailed descriptions - now just lists the access points

The implementation now uses OpenTelemetry's autoconfiguration via environment variables (OTEL_EXPORTER_PROMETHEUS_PORT and OTEL_METRICS_EXPORTER) configured in docker-compose.yml.

[Copilot]

Pull request overview

This PR implements comprehensive JVM runtime metrics collection using OpenTelemetry with Prometheus export and Grafana visualization capabilities. The implementation uses otel4s for Scala integration and provides automatic JVM metrics collection for memory, GC, threads, CPU, and other runtime statistics.

Key changes:

• Integrated OpenTelemetry with automatic configuration and JVM runtime metrics collection
• Added Prometheus and Grafana services to docker-compose for metrics monitoring
• Updated documentation with observability features and access points

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
server/src/main/scala/ru/trett/rss/server/Server.scala	Adds OpenTelemetry initialization with runtime metrics registration and proper resource management
build.sbt	Adds otel4s and OpenTelemetry runtime metrics dependencies
scripts/local-docker/docker-compose.yml	Configures Prometheus and Grafana services with proper environment variables for metrics export
scripts/local-docker/prometheus.yml	Defines Prometheus scraping configuration targeting the server metrics endpoint
README.md	Documents new observability features and access endpoints
client/package-lock.json	Minor npm dependency metadata cleanup

Files not reviewed (1)

• client/package-lock.json: Language not supported

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[trett]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

Applied all changes from the review in commit 20b6869:

1. ✅ Removed redundant cats.syntax.flatMap.* and cats.syntax.functor.* imports (already included in cats.implicits.*)
2. ✅ Fixed log message placement - now logs "OpenTelemetry metrics initialized" right after initialization via .evalTap() instead of later in the app flow
3. ✅ Added Grafana provisioning configuration to auto-configure Prometheus datasource on startup - created grafana/provisioning/datasources/prometheus.yml and updated docker-compose volume mount

[Copilot]

Pull request overview

Copilot reviewed 5 out of 7 changed files in this pull request and generated 1 comment.

Files not reviewed (1)

• client/package-lock.json: Language not supported

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

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