Introduce cluster 'team' setting and add to Member

Introduced cluster-team.md so we can grow the documentation with each
PR, but did not add it to the ToC yet.

(cherry picked from commit a06badaa03fa9f3c9a942b1468090f758c74a869)

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

@@ -65,6 +65,11 @@ akka {
     # move 'WeaklyUp' members to 'Up' status once convergence has been reached.
     allow-weakly-up-members = on
 
+    # Teams are used to make islands of the cluster that are colocated. It can be used
+    # to make the cluster "dc-aware", run the cluster in multiple availability zones or regions.
+    # The team is added to the list of roles of the node with the prefix "team-".
+    team = "default"
+
     # The roles of this member. List of strings, e.g. roles = ["A", "B"].
     # The roles are part of the membership information and can be used by
     # routers or other services to distribute work to certain member types,

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

@@ -93,7 +93,8 @@ final class ClusterSettings(val config: Config, val systemName: String) {
 
   val AllowWeaklyUpMembers = cc.getBoolean("allow-weakly-up-members")
 
-  val Roles: Set[String] = immutableSeq(cc.getStringList("roles")).toSet
+  val Team: String = cc.getString("team")
+  val Roles: Set[String] = immutableSeq(cc.getStringList("roles")).toSet + s"team-$Team"
   val MinNrOfMembers: Int = {
     cc.getInt("min-nr-of-members")
   } requiring (_ > 0, "min-nr-of-members must be > 0")

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

@@ -22,6 +22,9 @@ class Member private[cluster] (
   val status:                    MemberStatus,
   val roles:                     Set[String]) extends Serializable {
 
+  lazy val team = roles.find(_.startsWith("team-"))
+    .getOrElse(throw new IllegalStateException("Team undefined, should not be possible"))
+
   def address: Address = uniqueAddress.address
 
   override def hashCode = uniqueAddress.##

akka-cluster/src/multi-jvm/scala/akka/cluster/MBeanSpec.scala

@@ -120,28 +120,32 @@ abstract class MBeanSpec
              |    {
              |      "address": "${sortedNodes(0)}",
              |      "roles": [
-             |        "testNode"
+             |        "testNode",
+             |        "team-default"
              |      ],
              |      "status": "Up"
              |    },
              |    {
              |      "address": "${sortedNodes(1)}",
              |      "roles": [
-             |        "testNode"
+             |        "testNode",
+             |        "team-default"
              |      ],
              |      "status": "Up"
              |    },
              |    {
              |      "address": "${sortedNodes(2)}",
              |      "roles": [
-             |        "testNode"
+             |        "testNode",
+             |        "team-default"
              |      ],
              |      "status": "Up"
              |    },
              |    {
              |      "address": "${sortedNodes(3)}",
              |      "roles": [
-             |        "testNode"
+             |        "testNode",
+             |        "team-default"
              |      ],
              |      "status": "Up"
              |    }

akka-cluster/src/multi-jvm/scala/akka/cluster/QuickRestartSpec.scala

@@ -91,7 +91,7 @@ abstract class QuickRestartSpec
             Cluster(system).state.members.size should ===(totalNumberOfNodes)
             Cluster(system).state.members.map(_.status == MemberStatus.Up)
             // use the role to test that it is the new incarnation that joined, sneaky
-            Cluster(system).state.members.flatMap(_.roles) should ===(Set(s"round-$n"))
+            Cluster(system).state.members.flatMap(_.roles) should ===(Set(s"round-$n", "team-default"))
           }
         }
         enterBarrier("members-up-" + n)

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

@@ -5,9 +5,13 @@
 package akka.cluster
 
 import language.postfixOps
+import scala.concurrent.duration._
+
+import com.typesafe.config.ConfigFactory
+
 import akka.testkit.AkkaSpec
 import akka.dispatch.Dispatchers
-import scala.concurrent.duration._
+
 import akka.remote.PhiAccrualFailureDetector
 import akka.util.Helpers.ConfigOps
 import akka.actor.Address
@@ -41,7 +45,8 @@ class ClusterConfigSpec extends AkkaSpec {
       DownRemovalMargin should ===(Duration.Zero)
       MinNrOfMembers should ===(1)
       MinNrOfMembersOfRole should ===(Map.empty[String, Int])
-      Roles should ===(Set.empty[String])
+      Team should ===("default")
+      Roles should ===(Set("team-default"))
       JmxEnabled should ===(true)
       UseDispatcher should ===(Dispatchers.DefaultDispatcherId)
       GossipDifferentViewProbability should ===(0.8 +- 0.0001)
@@ -49,5 +54,20 @@ class ClusterConfigSpec extends AkkaSpec {
       SchedulerTickDuration should ===(33 millis)
       SchedulerTicksPerWheel should ===(512)
     }
+
+    "be able to parse non-default cluster config elements" in {
+      val settings = new ClusterSettings(ConfigFactory.parseString(
+        """
+          |akka {
+          |  cluster {
+          |    roles = [ "hamlet" ]
+          |    team = "blue"
+          |  }
+          |}
+        """.stripMargin).withFallback(ConfigFactory.load()), system.name)
+      import settings._
+      Roles should ===(Set("hamlet", "team-blue"))
+      Team should ===("blue")
+    }
   }
 }

akka-docs/src/main/paradox/java/cluster-team.md

@@ -0,0 +1 @@
+../scala/cluster-team.md

akka-docs/src/main/paradox/scala/cluster-team.md

@@ -0,0 +1,15 @@
+# Cluster Team
+
+@@@ note
+
+Cluster teams are a work-in-progress feature, and behavior is still expected to change.
+
+@@@
+
+Teams are used to define islands of the cluster that are colocated.
+They can be used to make the cluster "dc-aware", run the cluster in multiple availability zones or regions.
+
+Cluster nodes can be assigned to a team by setting the `akka.cluster.team` setting.
+When no team is specified, a node will belong to the 'default' team.
+
+The team is added to the list of roles of the node with the prefix "team-".