merge: Move OpenTelemetry integration outside core modules (#81)

This change removes the OpenTelemetry integration from the OpenDC modules. 
Previously, we chose to integrate OpenTelemetry to provide a unified way to 
report metrics to the users.

Although this worked as expected, the overhead of the OpenTelemetry when
collecting metrics during simulation was considerable and lacked more
optimization opportunities (other than providing a separate API
implementation). Furthermore, since we were tied to OpenTelemetry's SDK
implementation, we experienced issues with throttling and registering
multiple instruments.

We will instead use another approach, where we expose the core metrics
in OpenDC via specialized interfaces (see #80) such that
access is fast and can be done without having to interface with
OpenTelemetry. In addition, we will provide an adapter to that is able
to forward these metrics to OpenTelemetry implementations, so we can
still integrate with the wider ecosystem.

## Implementation Notes :hammer_and_pick:

* Remove OpenTelemetry from "compute" modules 
* Remove OpenTelemetry from "workflow" modules 
* Remove OpenTelemetry from "FaaS" modules
* Remove OpenTelemetry from TF20 experiment 
* Remove dependency on OpenTelemetry SDK 

## External Dependencies :four_leaf_clover:

* N/A

## Breaking API Changes :warning:

* Metrics are not anymore directly exposed via OpenTelemetry. Instead, an adapter needs to be used to access the data via OpenTelemetry.

1 files changed, 7 insertions, 9 deletions

diff --git a/opendc-experiments/opendc-experiments-serverless20/src/main/kotlin/org/opendc/experiments/serverless/ServerlessExperiment.kt b/opendc-experiments/opendc-experiments-serverless20/src/main/kotlin/org/opendc/experiments/serverless/ServerlessExperiment.kt
index 3312d6c0..1c357f67 100644
--- a/opendc-experiments/opendc-experiments-serverless20/src/main/kotlin/org/opendc/experiments/serverless/ServerlessExperiment.kt
+++ b/opendc-experiments/opendc-experiments-serverless20/src/main/kotlin/org/opendc/experiments/serverless/ServerlessExperiment.kt
@@ -23,8 +23,6 @@
 package org.opendc.experiments.serverless
 
 import com.typesafe.config.ConfigFactory
-import io.opentelemetry.api.metrics.MeterProvider
-import io.opentelemetry.sdk.metrics.SdkMeterProvider
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
@@ -44,7 +42,6 @@ import org.opendc.simulator.compute.model.MemoryUnit
 import org.opendc.simulator.compute.model.ProcessingNode
 import org.opendc.simulator.compute.model.ProcessingUnit
 import org.opendc.simulator.core.runBlockingSimulation
-import org.opendc.telemetry.sdk.toOtelClock
 import java.io.File
 import java.time.Duration
 import java.util.*
@@ -76,17 +73,18 @@ public class ServerlessExperiment : Experiment("Serverless") {
     private val coldStartModel by anyOf(ColdStartModel.LAMBDA, ColdStartModel.AZURE, ColdStartModel.GOOGLE)
 
     override fun doRun(repeat: Int): Unit = runBlockingSimulation {
-        val meterProvider: MeterProvider = SdkMeterProvider
-            .builder()
-            .setClock(clock.toOtelClock())
-            .build()
-
         val trace = ServerlessTraceReader().parse(File(config.getString("trace-path")))
         val traceById = trace.associateBy { it.id }
         val delayInjector = StochasticDelayInjector(coldStartModel, Random())
         val deployer = SimFunctionDeployer(clock, this, createMachineModel(), delayInjector) { FunctionTraceWorkload(traceById.getValue(it.name)) }
         val service =
-            FaaSService(coroutineContext, clock, meterProvider, deployer, routingPolicy, FunctionTerminationPolicyFixed(coroutineContext, clock, timeout = Duration.ofMinutes(10)))
+            FaaSService(
+                coroutineContext,
+                clock,
+                deployer,
+                routingPolicy,
+                FunctionTerminationPolicyFixed(coroutineContext, clock, timeout = Duration.ofMinutes(10))
+            )
         val client = service.newClient()
 
         coroutineScope {