chore: WPB-28096 Enable JVM metrics and add business metrics

build.gradle.kts

@@ -39,6 +39,10 @@ dependencies {
     implementation(libs.ktor.server.content.negotiation)
     implementation(libs.ktor.server.logging)
 
+    // Metrics
+    implementation(libs.ktor.server.metrics.micrometer)
+    implementation(libs.micrometer.registry.prometheus)
+
     // Serialization
     implementation(libs.ktor.server.serialization)
     implementation(libs.kotlinx.serialization.json)

gradle/libs.versions.toml

@@ -12,6 +12,7 @@ wire-sdk-version = "0.2.1"
 redis-version = "6.7.1.RELEASE"
 mustache-version = "0.9.14"
 mockk-version = "1.14.11"
+micrometer-version = "1.16.0"
 shadow = "9.6.1"
 
 [plugins]
@@ -29,6 +30,9 @@ ktor-server-test-host = { module = "io.ktor:ktor-server-test-host", version.ref
 ktor-server-content-negotiation = { module = "io.ktor:ktor-server-content-negotiation", version.ref = "ktor-version" }
 ktor-server-serialization = { module = "io.ktor:ktor-serialization-kotlinx-json", version.ref = "ktor-version" }
 ktor-server-logging = { module = "io.ktor:ktor-client-logging", version.ref = "ktor-version" }
+# Pinned to the version koin-ktor already forces onto ktor-server-core; 3.2.3 is binary incompatible with it.
+ktor-server-metrics-micrometer = { module = "io.ktor:ktor-server-metrics-micrometer", version = "3.4.0" }
+micrometer-registry-prometheus = { module = "io.micrometer:micrometer-registry-prometheus", version.ref = "micrometer-version" }
 kotlinx-serialization-json = { module = "org.jetbrains.kotlinx:kotlinx-serialization-json", version.ref = "kotlin-serialization" }
 koin-ktor = { module = "io.insert-koin:koin-ktor", version.ref = "koin-version" }
 koin-test = { module = "io.insert-koin:koin-test", version.ref = "koin-version" }

src/main/kotlin/com/wire/github/Application.kt

@@ -1,6 +1,7 @@
 package com.wire.github
 
 import com.wire.github.config.projectModules
+import com.wire.github.metrics.configureMetrics
 import com.wire.github.util.ENV_VAR_PORT
 import io.ktor.server.application.Application
 import io.ktor.server.engine.embeddedServer
@@ -22,4 +23,5 @@ fun main() {
 
 fun Application.module() {
     configureRouting()
+    configureMetrics()
 }

src/main/kotlin/com/wire/github/EventsHandler.kt

@@ -1,5 +1,6 @@
 package com.wire.github
 
+import com.wire.github.metrics.UsageMetrics
 import com.wire.github.util.ENV_VAR_HOST
 import com.wire.github.util.SessionIdentifierGenerator
 import com.wire.github.util.toStorageKey
@@ -16,6 +17,7 @@ class EventsHandler : WireEventsHandlerSuspending() {
     private val logger = LoggerFactory.getLogger(this::class.java)
     private val redisConnection = GlobalContext.get().get<StatefulRedisConnection<String, String>>()
     private val storage = redisConnection.sync()
+    private val usageMetrics = GlobalContext.get().get<UsageMetrics>()
 
     override suspend fun onTextMessageReceived(wireMessage: WireMessage.Text) {
         if (wireMessage.text.equals(HELP_COMMAND, ignoreCase = true)) {
@@ -24,6 +26,7 @@ class EventsHandler : WireEventsHandlerSuspending() {
                     "conversationId: ${wireMessage.conversationId}, " +
                     "senderId: ${wireMessage.sender}"
             )
+            usageMetrics.onHelpCommand()
             val message = formatSetupInstructions(
                 conversationId = wireMessage.conversationId,
                 secret = storage.get(wireMessage.conversationId.toStorageKey())
@@ -50,6 +53,7 @@ class EventsHandler : WireEventsHandlerSuspending() {
             "Event received. Event: AppAddedToConversation, " +
                 "conversationId: ${conversation.id}"
         )
+        usageMetrics.onAppAddedToConversation()
         val message = buildString {
             appendLine(WELCOME_TEXT)
             appendLine(formatSetupInstructions(conversationId = conversation.id))

src/main/kotlin/com/wire/github/Routing.kt

@@ -1,5 +1,6 @@
 package com.wire.github
 
+import com.wire.github.metrics.UsageMetrics
 import com.wire.github.response.model.GitHubResponse
 import com.wire.github.util.KtxSerializer
 import com.wire.github.util.SignatureValidator
@@ -20,6 +21,7 @@ import io.ktor.server.routing.application
 import io.ktor.server.routing.get
 import io.ktor.server.routing.post
 import io.ktor.server.routing.routing
+import java.io.IOException
 import java.util.UUID
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.SerializationException
@@ -35,6 +37,7 @@ fun Application.configureRouting() {
     val wireAppSdk = GlobalContext.get().get<WireAppSdk>()
     val signatureValidator = GlobalContext.get().get<SignatureValidator>()
     val templateHandler = GlobalContext.get().get<TemplateHandler>()
+    val usageMetrics = GlobalContext.get().get<UsageMetrics>()
 
     routing {
         trace {
@@ -72,19 +75,40 @@ fun Application.configureRouting() {
             val payload = call.receiveText()
 
             // Validation of received signature
-            val isSignatureValid = signatureValidator.isValid(
-                conversationId = conversationId,
-                conversationDomain = conversationDomain,
-                signature = signature,
-                payload = payload
-            )
+            val isSignatureValid = try {
+                signatureValidator.isValid(
+                    conversationId = conversationId,
+                    conversationDomain = conversationDomain,
+                    signature = signature,
+                    payload = payload
+                )
+            } catch (exception: IOException) {
+                application.log.warn(
+                    "No secret stored for conversation $conversationId@$conversationDomain, " +
+                        "rejecting $event delivery $delivery",
+                    exception
+                )
+
+                // A missing secret can never validate on retry, so this is a permanent
+                // rejection (403) rather than a server error (500) GitHub would redeliver.
+                return@post call.respond(
+                    status = HttpStatusCode.Forbidden,
+                    message = "Invalid Signature for Conversation"
+                )
+            }
             if (!isSignatureValid) {
+                application.log.warn(
+                    "Invalid signature for conversation $conversationId@$conversationDomain, " +
+                        "rejecting $event delivery $delivery"
+                )
                 return@post call.respond(
                     status = HttpStatusCode.Forbidden,
                     message = "Invalid Signature for Conversation"
                 )
             }
 
+            usageMetrics.onWebhookEventReceived(event = event)
+
             val response = try {
                 KtxSerializer.json.decodeFromString<GitHubResponse>(payload)
             } catch (exception: SerializationException) {
@@ -98,18 +122,25 @@ fun Application.configureRouting() {
                 response = response
             )
 
-            messageTemplate?.let { message ->
-                wireAppSdk.getApplicationManager().sendMessage(
-                    message = WireMessage.Text.create(
-                        conversationId = QualifiedId(
-                            id = UUID.fromString(conversationId),
-                            domain = conversationDomain
-                        ),
-                        text = message
-                    )
+            if (messageTemplate == null) {
+                usageMetrics.onUnsupportedEvent(
+                    event = event,
+                    action = response.action
                 )
+                return@post call.response.status(HttpStatusCode.OK)
             }
 
+            wireAppSdk.getApplicationManager().sendMessage(
+                message = WireMessage.Text.create(
+                    conversationId = QualifiedId(
+                        id = UUID.fromString(conversationId),
+                        domain = conversationDomain
+                    ),
+                    text = messageTemplate
+                )
+            )
+            usageMetrics.onNotificationSent(event = event)
+
             return@post call.response.status(HttpStatusCode.OK)
         }
     }

src/main/kotlin/com/wire/github/config/Modules.kt

@@ -1,6 +1,7 @@
 package com.wire.github.config
 
 import com.wire.github.EventsHandler
+import com.wire.github.metrics.UsageMetrics
 import com.wire.github.util.ENV_VAR_API_HOST
 import com.wire.github.util.ENV_VAR_API_TOKEN
 import com.wire.github.util.ENV_VAR_APPLICATION_ID
@@ -12,6 +13,8 @@ import com.wire.sdk.WireAppSdk
 import io.ktor.utils.io.core.toByteArray
 import io.lettuce.core.RedisClient
 import io.lettuce.core.api.StatefulRedisConnection
+import io.micrometer.prometheusmetrics.PrometheusConfig
+import io.micrometer.prometheusmetrics.PrometheusMeterRegistry
 import org.koin.dsl.module
 
 val projectModules = module {
@@ -24,6 +27,8 @@ val projectModules = module {
     single { TemplateHandler() }
     single { RedisClient.create(ENV_VAR_REDIS_URL) }
     single<StatefulRedisConnection<String, String>> { get<RedisClient>().connect() }
+    single { PrometheusMeterRegistry(PrometheusConfig.DEFAULT) }
+    single { UsageMetrics(registry = get<PrometheusMeterRegistry>()) }
 }
 
 private fun wireAppSdk(): WireAppSdk =

src/main/kotlin/com/wire/github/metrics/Metrics.kt

@@ -0,0 +1,24 @@
+package com.wire.github.metrics
+
+import io.ktor.server.application.Application
+import io.ktor.server.application.install
+import io.ktor.server.metrics.micrometer.MicrometerMetrics
+import io.ktor.server.response.respond
+import io.ktor.server.routing.get
+import io.ktor.server.routing.routing
+import io.micrometer.prometheusmetrics.PrometheusMeterRegistry
+import org.koin.core.context.GlobalContext
+
+fun Application.configureMetrics() {
+    val prometheusRegistry = GlobalContext.get().get<PrometheusMeterRegistry>()
+
+    install(plugin = MicrometerMetrics) {
+        registry = prometheusRegistry
+    }
+
+    routing {
+        get("/metrics") {
+            call.respond(prometheusRegistry.scrape())
+        }
+    }
+}

src/main/kotlin/com/wire/github/metrics/UsageMetrics.kt

@@ -0,0 +1,92 @@
+package com.wire.github.metrics
+
+import io.micrometer.core.instrument.Counter
+import io.micrometer.core.instrument.MeterRegistry
+
+class UsageMetrics(
+    private val registry: MeterRegistry
+) {
+    private val helpCommandCounter: Counter = Counter
+        .builder("githubapp_help_commands_total")
+        .description("Number of Help commands received")
+        .register(registry)
+
+    private val appAddedToConversationCounter: Counter = Counter
+        .builder("githubapp_added_to_conversation_total")
+        .description("Number of times the app is added to a conversation")
+        .register(registry)
+
+    private fun webhookEventsReceivedCounter(event: String): Counter =
+        Counter
+            .builder("githubapp_webhook_events_received_total")
+            .description("Number of GitHub webhook deliveries accepted for processing")
+            .tag(TAG_EVENT, event)
+            .register(registry)
+
+    private fun notificationsSentCounter(event: String): Counter =
+        Counter
+            .builder("githubapp_notifications_sent_total")
+            .description("Number of messages sent to a conversation for a webhook delivery")
+            .tag(TAG_EVENT, event)
+            .register(registry)
+
+    private fun unsupportedEventsCounter(
+        event: String,
+        action: String?
+    ): Counter =
+        Counter
+            .builder("githubapp_unsupported_events_total")
+            .description("Number of webhook deliveries with no matching message template")
+            .tag(TAG_EVENT, event)
+            .tag(TAG_ACTION, action ?: NO_ACTION)
+            .register(registry)
+
+    /**
+     * A help command was received in a conversation.
+     * Signals how often users come back for the setup instructions.
+     */
+    fun onHelpCommand() {
+        helpCommandCounter.increment()
+    }
+
+    /**
+     * The app was added to a conversation.
+     * First step of onboarding, before any webhook is configured.
+     */
+    fun onAppAddedToConversation() {
+        appAddedToConversationCounter.increment()
+    }
+
+    /**
+     * A webhook delivery passed signature validation and entered processing.
+     * Top of the delivery funnel.
+     */
+    fun onWebhookEventReceived(event: String) {
+        webhookEventsReceivedCounter(event).increment()
+    }
+
+    /**
+     * A webhook delivery was rendered and sent to the conversation.
+     * Bottom of the delivery funnel.
+     */
+    fun onNotificationSent(event: String) {
+        notificationsSentCounter(event).increment()
+    }
+
+    /**
+     * A webhook delivery had no matching message template, so nothing was sent.
+     * Ranks the event/action pairs worth adding templates for.
+     */
+    fun onUnsupportedEvent(
+        event: String,
+        action: String?
+    ) {
+        unsupportedEventsCounter(event, action).increment()
+    }
+
+    private companion object {
+        const val TAG_EVENT = "event"
+        const val TAG_ACTION = "action"
+        const val NO_ACTION = "none"
+    }
+}