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, 10 insertions, 13 deletions

diff --git a/opendc-faas/opendc-faas-service/src/test/kotlin/org/opendc/faas/service/FaaSServiceTest.kt b/opendc-faas/opendc-faas-service/src/test/kotlin/org/opendc/faas/service/FaaSServiceTest.kt
index 1612e10b..560039c1 100644
--- a/opendc-faas/opendc-faas-service/src/test/kotlin/org/opendc/faas/service/FaaSServiceTest.kt
+++ b/opendc-faas/opendc-faas-service/src/test/kotlin/org/opendc/faas/service/FaaSServiceTest.kt
@@ -23,8 +23,6 @@
 package org.opendc.faas.service
 
 import io.mockk.*
-import io.opentelemetry.api.metrics.MeterProvider
-import kotlinx.coroutines.ExperimentalCoroutinesApi
 import org.junit.jupiter.api.Assertions.*
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertDoesNotThrow
@@ -39,12 +37,11 @@ import java.util.*
 /**
  * Test suite for the [FaaSService] implementation.
  */
-@OptIn(ExperimentalCoroutinesApi::class)
 internal class FaaSServiceTest {
 
     @Test
     fun testClientState() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = assertDoesNotThrow { service.newClient() }
         assertDoesNotThrow { client.close() }
@@ -58,7 +55,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientInvokeUnknown() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -67,7 +64,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionCreation() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -78,7 +75,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionQuery() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -91,7 +88,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionFindById() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -104,7 +101,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionFindByName() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -117,7 +114,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionDuplicateName() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -128,7 +125,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionDelete() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = service.newClient()
         val function = client.newFunction("test", 128)
@@ -142,7 +139,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionCannotInvokeDeleted() = runBlockingSimulation {
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, mockk(), mockk(), mockk())
 
         val client = service.newClient()
         val function = client.newFunction("test", 128)
@@ -155,7 +152,7 @@ internal class FaaSServiceTest {
     @Test
     fun testClientFunctionInvoke() = runBlockingSimulation {
         val deployer = mockk<FunctionDeployer>()
-        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), deployer, mockk(), mockk(relaxUnitFun = true))
+        val service = FaaSService(coroutineContext, clock, deployer, mockk(), mockk(relaxUnitFun = true))
 
         every { deployer.deploy(any(), any()) } answers {
             object : FunctionInstance {