refactor(telemetry): Create separate MeterProvider per service/host

This change refactors the telemetry implementation by creating a
separate MeterProvider per service or host. This means we have to keep
track of multiple metric producers, but that we can attach resource
information to each of the MeterProviders like we would in a real world
scenario.

6 files changed, 41 insertions, 36 deletions

diff --git a/opendc-faas/opendc-faas-service/build.gradle.kts b/opendc-faas/opendc-faas-service/build.gradle.kts
index 63bed8bc..6f4fcc9b 100644
--- a/opendc-faas/opendc-faas-service/build.gradle.kts
+++ b/opendc-faas/opendc-faas-service/build.gradle.kts
@@ -35,6 +35,7 @@ dependencies {
     api(projects.opendcTelemetry.opendcTelemetryApi)
     implementation(projects.opendcUtils)
     implementation(libs.kotlin.logging)
+    implementation(libs.opentelemetry.semconv)
 
     testImplementation(projects.opendcSimulator.opendcSimulatorCore)
     testRuntimeOnly(libs.log4j.slf4j)
diff --git a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/FaaSService.kt b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/FaaSService.kt
index 7e716a34..1d5331cb 100644
--- a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/FaaSService.kt
+++ b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/FaaSService.kt
@@ -23,6 +23,7 @@
 package org.opendc.faas.service
 
 import io.opentelemetry.api.metrics.Meter
+import io.opentelemetry.api.metrics.MeterProvider
 import org.opendc.faas.api.FaaSClient
 import org.opendc.faas.service.autoscaler.FunctionTerminationPolicy
 import org.opendc.faas.service.deployer.FunctionDeployer
@@ -51,7 +52,7 @@ public interface FaaSService : AutoCloseable {
          *
          * @param context The [CoroutineContext] to use in the service.
          * @param clock The clock instance to use.
-         * @param meter The meter to report metrics to.
+         * @param meterProvider The [MeterProvider] to create a [Meter] with.
          * @param deployer the [FunctionDeployer] to use for deploying function instances.
          * @param routingPolicy The policy to route function invocations.
          * @param terminationPolicy The policy for terminating function instances.
@@ -59,12 +60,12 @@ public interface FaaSService : AutoCloseable {
         public operator fun invoke(
             context: CoroutineContext,
             clock: Clock,
-            meter: Meter,
+            meterProvider: MeterProvider,
             deployer: FunctionDeployer,
             routingPolicy: RoutingPolicy,
             terminationPolicy: FunctionTerminationPolicy,
         ): FaaSService {
-            return FaaSServiceImpl(context, clock, meter, deployer, routingPolicy, terminationPolicy)
+            return FaaSServiceImpl(context, clock, meterProvider, deployer, routingPolicy, terminationPolicy)
         }
     }
 }
diff --git a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/FunctionObject.kt b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/FunctionObject.kt
index a1cb1dbf..54df2b59 100644
--- a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/FunctionObject.kt
+++ b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/FunctionObject.kt
@@ -28,6 +28,7 @@ import io.opentelemetry.api.metrics.BoundLongCounter
 import io.opentelemetry.api.metrics.BoundLongHistogram
 import io.opentelemetry.api.metrics.BoundLongUpDownCounter
 import io.opentelemetry.api.metrics.Meter
+import io.opentelemetry.semconv.resource.attributes.ResourceAttributes
 import org.opendc.faas.service.deployer.FunctionInstance
 import java.util.*
 
@@ -43,9 +44,14 @@ public class FunctionObject(
     meta: Map<String, Any>
 ) : AutoCloseable {
     /**
-     * The function identifier attached to the metrics.
+     * The attributes of this function.
      */
-    private val functionId = AttributeKey.stringKey("function")
+    public val attributes: Attributes = Attributes.builder()
+        .put(ResourceAttributes.FAAS_ID, uid.toString())
+        .put(ResourceAttributes.FAAS_NAME, name)
+        .put(ResourceAttributes.FAAS_MAX_MEMORY, allocatedMemory)
+        .put(AttributeKey.stringArrayKey("faas.labels"), labels.map { (k, v) -> "$k:$v" })
+        .build()
 
     /**
      * The total amount of function invocations received by the function.
@@ -54,7 +60,7 @@ public class FunctionObject(
         .setDescription("Number of function invocations")
         .setUnit("1")
         .build()
-        .bind(Attributes.of(functionId, uid.toString()))
+        .bind(attributes)
 
     /**
      * The amount of function invocations that could be handled directly.
@@ -63,7 +69,7 @@ public class FunctionObject(
         .setDescription("Number of function invocations handled directly")
         .setUnit("1")
         .build()
-        .bind(Attributes.of(functionId, uid.toString()))
+        .bind(attributes)
 
     /**
      * The amount of function invocations that were delayed due to function deployment.
@@ -72,7 +78,7 @@ public class FunctionObject(
         .setDescription("Number of function invocations that are delayed")
         .setUnit("1")
         .build()
-        .bind(Attributes.of(functionId, uid.toString()))
+        .bind(attributes)
 
     /**
      * The amount of function invocations that failed.
@@ -81,7 +87,7 @@ public class FunctionObject(
         .setDescription("Number of function invocations that failed")
         .setUnit("1")
         .build()
-        .bind(Attributes.of(functionId, uid.toString()))
+        .bind(attributes)
 
     /**
      * The amount of instances for this function.
@@ -90,7 +96,7 @@ public class FunctionObject(
         .setDescription("Number of active function instances")
         .setUnit("1")
         .build()
-        .bind(Attributes.of(functionId, uid.toString()))
+        .bind(attributes)
 
     /**
      * The amount of idle instances for this function.
@@ -99,7 +105,7 @@ public class FunctionObject(
         .setDescription("Number of idle function instances")
         .setUnit("1")
         .build()
-        .bind(Attributes.of(functionId, uid.toString()))
+        .bind(attributes)
 
     /**
      * The time that the function waited.
@@ -109,7 +115,7 @@ public class FunctionObject(
         .setDescription("Time the function has to wait before being started")
         .setUnit("ms")
         .build()
-        .bind(Attributes.of(functionId, uid.toString()))
+        .bind(attributes)
 
     /**
      * The time that the function was running.
@@ -119,7 +125,7 @@ public class FunctionObject(
         .setDescription("Time the function was running")
         .setUnit("ms")
         .build()
-        .bind(Attributes.of(functionId, uid.toString()))
+        .bind(attributes)
 
     /**
      * The instances associated with this function.
diff --git a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/autoscaler/FunctionTerminationPolicyFixed.kt b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/autoscaler/FunctionTerminationPolicyFixed.kt
index 1e224ed1..63dbadc7 100644
--- a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/autoscaler/FunctionTerminationPolicyFixed.kt
+++ b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/autoscaler/FunctionTerminationPolicyFixed.kt
@@ -26,6 +26,7 @@ import org.opendc.faas.service.deployer.FunctionInstance
 import org.opendc.faas.service.deployer.FunctionInstanceState
 import org.opendc.utils.TimerScheduler
 import java.time.Clock
+import java.time.Duration
 import kotlin.coroutines.CoroutineContext
 
 /**
@@ -36,7 +37,7 @@ import kotlin.coroutines.CoroutineContext
 public class FunctionTerminationPolicyFixed(
     context: CoroutineContext,
     clock: Clock,
-    public val timeout: Long
+    public val timeout: Duration
 ) : FunctionTerminationPolicy {
     /**
      * The [TimerScheduler] used to schedule the function terminations.
@@ -60,6 +61,6 @@ public class FunctionTerminationPolicyFixed(
      * Schedule termination for the specified [instance].
      */
     private fun schedule(instance: FunctionInstance) {
-        scheduler.startSingleTimer(instance, delay = timeout) { instance.close() }
+        scheduler.startSingleTimer(instance, delay = timeout.toMillis()) { instance.close() }
     }
 }
diff --git a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/internal/FaaSServiceImpl.kt b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/internal/FaaSServiceImpl.kt
index ccf9a5d9..3b560cd3 100644
--- a/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/internal/FaaSServiceImpl.kt
+++ b/opendc-faas/opendc-faas-service/src/main/kotlin/org/opendc/faas/service/internal/FaaSServiceImpl.kt
@@ -23,6 +23,7 @@
 package org.opendc.faas.service.internal
 
 import io.opentelemetry.api.metrics.Meter
+import io.opentelemetry.api.metrics.MeterProvider
 import kotlinx.coroutines.*
 import kotlinx.coroutines.intrinsics.startCoroutineCancellable
 import mu.KotlinLogging
@@ -54,7 +55,7 @@ import kotlin.coroutines.resumeWithException
 internal class FaaSServiceImpl(
     context: CoroutineContext,
     private val clock: Clock,
-    private val meter: Meter,
+    private val meterProvider: MeterProvider,
     private val deployer: FunctionDeployer,
     private val routingPolicy: RoutingPolicy,
     private val terminationPolicy: FunctionTerminationPolicy
@@ -70,6 +71,11 @@ internal class FaaSServiceImpl(
     private val logger = KotlinLogging.logger {}
 
     /**
+     * The [Meter] that collects the metrics of this service.
+     */
+    private val meter = meterProvider.get("org.opendc.faas.service")
+
+    /**
      * The [TimerScheduler] to use for scheduling the scheduler cycles.
      */
     private val scheduler: TimerScheduler<Unit> = TimerScheduler(scope.coroutineContext, clock)
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 6b99684a..1612e10b 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
@@ -44,8 +44,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientState() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = assertDoesNotThrow { service.newClient() }
         assertDoesNotThrow { client.close() }
@@ -59,8 +58,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientInvokeUnknown() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -69,8 +67,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionCreation() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -81,8 +78,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionQuery() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -95,8 +91,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionFindById() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -109,8 +104,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionFindByName() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -123,8 +117,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionDuplicateName() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = service.newClient()
 
@@ -135,8 +128,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionDelete() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = service.newClient()
         val function = client.newFunction("test", 128)
@@ -150,8 +142,7 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionCannotInvokeDeleted() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
-        val service = FaaSService(coroutineContext, clock, meter, mockk(), mockk(), mockk())
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), mockk(), mockk(), mockk())
 
         val client = service.newClient()
         val function = client.newFunction("test", 128)
@@ -163,9 +154,8 @@ internal class FaaSServiceTest {
 
     @Test
     fun testClientFunctionInvoke() = runBlockingSimulation {
-        val meter = MeterProvider.noop().get("opendc-faas")
         val deployer = mockk<FunctionDeployer>()
-        val service = FaaSService(coroutineContext, clock, meter, deployer, mockk(), mockk(relaxUnitFun = true))
+        val service = FaaSService(coroutineContext, clock, MeterProvider.noop(), deployer, mockk(), mockk(relaxUnitFun = true))
 
         every { deployer.deploy(any(), any()) } answers {
             object : FunctionInstance {