Cluster event listener that logs all events #25832 (#25918)

akka-cluster/src/main/resources/reference.conf

@@ -114,6 +114,10 @@ akka {
     # Enable/disable info level logging of cluster events
     log-info = on
 
+    # Enable/disable verbose info-level logging of cluster events
+    # for temporary troubleshooting. Defaults to 'off'.
+    log-info-verbose = off
+
     # Enable or disable JMX MBeans for management of the cluster
     jmx.enabled = on
 

akka-cluster/src/main/scala/akka/cluster/ClusterReadView.scala

@@ -21,6 +21,7 @@ import akka.util.OptionVal
  * cluster events published on the event bus.
  */
 private[akka] class ClusterReadView(cluster: Cluster) extends Closeable {
+  import cluster.InfoLogger._
 
   /**
    * Current state
@@ -98,6 +99,15 @@ private[akka] class ClusterReadView(cluster: Cluster) extends Closeable {
               }
             case _ ⇒
           }
+
+          // once captured, optional verbose logging of event
+          e match {
+            case _: SeenChanged ⇒ // ignore
+            case event ⇒
+              if (cluster.settings.LogInfoVerbose)
+                logInfo(" - event {}", event)
+          }
+
         case s: CurrentClusterState ⇒ _state = s
       }
     }).withDispatcher(cluster.settings.UseDispatcher).withDeploy(Deploy.local), name = "clusterEventBusListener")

akka-cluster/src/main/scala/akka/cluster/ClusterSettings.scala

@@ -38,7 +38,8 @@ final class ClusterSettings(val config: Config, val systemName: String) {
   import ClusterSettings._
   private val cc = config.getConfig("akka.cluster")
 
-  val LogInfo: Boolean = cc.getBoolean("log-info")
+  val LogInfoVerbose: Boolean = cc.getBoolean("log-info-verbose")
+  val LogInfo: Boolean = LogInfoVerbose || cc.getBoolean("log-info")
   val FailureDetectorConfig: Config = cc.getConfig("failure-detector")
   val FailureDetectorImplementationClass: String = FailureDetectorConfig.getString("implementation-class")
   val HeartbeatInterval: FiniteDuration = {

akka-cluster/src/test/scala/akka/cluster/ClusterLogSpec.scala

@@ -5,8 +5,8 @@
 package akka.cluster
 
 import akka.actor.{ Address, ExtendedActorSystem }
-import akka.cluster.InternalClusterAction.LeaderActionsTick
 import akka.testkit.{ AkkaSpec, EventFilter, ImplicitSender }
+import com.typesafe.config.{ Config, ConfigFactory }
 
 object ClusterLogSpec {
   val config = """
@@ -25,33 +25,79 @@ object ClusterLogSpec {
 
 }
 
-class ClusterLogSpec extends AkkaSpec(ClusterLogSpec.config) with ImplicitSender {
+abstract class ClusterLogSpec(config: Config) extends AkkaSpec(config) with ImplicitSender {
 
-  val selfAddress: Address = system.asInstanceOf[ExtendedActorSystem].provider.getDefaultAddress
+  def this(s: String) = this(ConfigFactory.parseString(s))
 
-  val cluster = Cluster(system)
-  def clusterView: ClusterReadView = cluster.readView
+  protected val selfAddress: Address = system.asInstanceOf[ExtendedActorSystem].provider.getDefaultAddress
 
-  "A Cluster" must {
+  protected val upLogMessage = " - event MemberUp"
 
-    "Log a message when becoming and stopping being a leader" in {
-      EventFilter
-        .info(occurrences = 1, pattern = "is the new leader")
-        .intercept {
-          cluster.join(selfAddress)
-        }
+  protected val downLogMessage = " - event MemberDowned"
 
+  protected val cluster = Cluster(system)
+
+  protected def clusterView: ClusterReadView = cluster.readView
+
+  protected def awaitUp(): Unit = {
     awaitCond(clusterView.isSingletonCluster)
     clusterView.self.address should ===(selfAddress)
     clusterView.members.map(_.address) should ===(Set(selfAddress))
     awaitAssert(clusterView.status should ===(MemberStatus.Up))
-
-      EventFilter
-        .info(occurrences = 1, pattern = "is no longer the leader")
-        .intercept {
-          cluster.down(selfAddress)
-        }
   }
 
+  /** The expected log info pattern to intercept after a `cluster.join`. */
+  protected def join(expected: String): Unit =
+    EventFilter.
+      info(occurrences = 1, pattern = expected).
+      intercept(cluster.join(selfAddress))
+
+  /** The expected log info pattern to intercept after a `cluster.down`. */
+  protected def down(expected: String): Unit =
+    EventFilter.
+      info(occurrences = 1, pattern = expected).
+      intercept(cluster.down(selfAddress))
+}
+
+class ClusterLogDefaultSpec extends ClusterLogSpec(ClusterLogSpec.config) {
+
+  "A Cluster" must {
+
+    "Log a message when becoming and stopping being a leader" in {
+      cluster.settings.LogInfo should ===(true)
+      cluster.settings.LogInfoVerbose should ===(false)
+      join("is the new leader")
+      awaitUp()
+      down("is no longer the leader")
+    }
+  }
+}
+
+class ClusterLogVerboseDefaultSpec extends ClusterLogSpec(
+  ConfigFactory.parseString(ClusterLogSpec.config)) {
+
+  "A Cluster" must {
+
+    "not log verbose cluster events by default" in {
+      cluster.settings.LogInfoVerbose should ===(false)
+      intercept[AssertionError](join(upLogMessage))
+      awaitUp()
+      intercept[AssertionError](down(downLogMessage))
+    }
+  }
+}
+
+class ClusterLogVerboseEnabledSpec extends ClusterLogSpec(
+  ConfigFactory.parseString("akka.cluster.log-info-verbose = on").
+    withFallback(ConfigFactory.parseString(ClusterLogSpec.config))) {
+
+  "A Cluster" must {
+
+    "log verbose cluster events when 'log-info-verbose = on'" in {
+      cluster.settings.LogInfoVerbose should ===(true)
+      join(upLogMessage)
+      awaitUp()
+      down(downLogMessage)
+    }
   }
 }

akka-docs/src/main/paradox/cluster-usage.md

@@ -874,6 +874,12 @@ You can silence the logging of cluster events at info level with configuration p
 akka.cluster.log-info = off
 ```
 
+You can enable verbose logging of cluster events at info level, e.g. for temporary troubleshooting, with configuration property:
+
+```
+akka.cluster.log-info-verbose = on
+```
+
 <a id="cluster-dispatcher"></a>
 ### Cluster Dispatcher