[constraints] by hostname

docs/docs/api.md

@@ -387,8 +387,9 @@ When specifying the `command` field in your job hash, use `url-runner.bash` (mak
 
 ## Constraints
 
-These constraints will currently only work against attributes that are specifically set on the Mesos slaves [as described in the Mesos documentation](http://mesos.apache.org/documentation/latest/configuration).
-(i.e. the `hostname` attribute is not currently automatically available for constraints [as it is in Marathon](https://mesosphere.github.io/marathon/docs/constraints))
+These constraints will work against attributes that are specifically set on the Mesos slaves [as described in the Mesos documentation](http://mesos.apache.org/documentation/latest/configuration).
+
+If a `hostname` attribute is not explicitly specified, one will automatically be created and made available for constraints [as it is in Marathon](https://mesosphere.github.io/marathon/docs/constraints). It should be noted that calling out specific hostnames is not resilient to slave failure and should be avoided if possible.
 
 ### EQUALS constraint
 

src/main/scala/org/apache/mesos/chronos/scheduler/mesos/ConstraintChecker.scala

@@ -0,0 +1,35 @@
+package org.apache.mesos.chronos.scheduler.mesos
+
+import org.apache.mesos.Protos
+import org.apache.mesos.chronos.scheduler.jobs.constraints.Constraint
+import java.util.logging.Logger
+import scala.collection.JavaConverters._
+
+/**
+ * Helper for checking resource offer against job constraints
+ *
+ * @author tony kerz (anthony.kerz@gmail.com)
+ */
+class ConstraintChecker {
+  private[this] val log = Logger.getLogger(getClass.getName)
+  val Hostname = "hostname"
+
+  def checkConstraints(offer: Protos.Offer, constraints: Seq[Constraint]): Boolean = {
+    var attributes = offer.getAttributesList.asScala
+
+    if (!attributes.exists(attr => attr.getName == Hostname)) {
+      log.fine(s"adding hostname-attribute=${offer.getHostname} to offer=${offer}")
+      val hostnameText = Protos.Value.Text.newBuilder().setValue(offer.getHostname).build()
+      val hostnameAttribute = Protos.Attribute.newBuilder().setName(Hostname).setText(hostnameText).setType(Protos.Value.Type.TEXT).build()
+      attributes = offer.getAttributesList.asScala :+ hostnameAttribute
+    }
+
+    constraints.foreach { c =>
+      if (!c.matches(attributes)) {
+        return false
+      }
+    }
+    true
+  }
+
+}

src/main/scala/org/apache/mesos/chronos/scheduler/mesos/MesosJobFramework.scala

@@ -28,7 +28,8 @@ class MesosJobFramework @Inject()(
                                    val config: SchedulerConfiguration,
                                    val frameworkIdUtil: FrameworkIdUtil,
                                    val taskBuilder: MesosTaskBuilder,
-                                   val mesosOfferReviver: MesosOfferReviver)
+                                   val mesosOfferReviver: MesosOfferReviver,
+                                   val constraintChecker: ConstraintChecker = new ConstraintChecker())
   extends Scheduler {
 
   val frameworkName = "chronos"
@@ -116,15 +117,6 @@ class MesosJobFramework @Inject()(
   def generateLaunchableTasks(offerResources: mutable.HashMap[Offer, Resources]): mutable.Buffer[(String, BaseJob, Offer)] = {
     val tasks = mutable.Buffer[(String, BaseJob, Offer)]()
 
-    def checkConstraints(attributes: Seq[Protos.Attribute], constraints: Seq[Constraint]): Boolean = {
-      constraints.foreach { c =>
-        if (!c.matches(attributes)) {
-          return false
-        }
-      }
-      true
-    }
-
     @tailrec
     def generate() {
       taskManager.getTask match {
@@ -143,7 +135,7 @@ class MesosJobFramework @Inject()(
               case None =>
                 val neededResources = new Resources(job)
                 offerResources.toIterator.find { ors =>
-                  ors._2.canSatisfy(neededResources) && checkConstraints(ors._1.getAttributesList.asScala, job.constraints)
+                  ors._2.canSatisfy(neededResources) && constraintChecker.checkConstraints(ors._1, job.constraints)
                 } match {
                   case Some((offer, resources)) =>
                     // Subtract this job's resource requirements from the remaining available resources in this offer.

src/test/scala/org/apache/mesos/chronos/scheduler/mesos/ConstraintCheckerSpec.scala

@@ -0,0 +1,85 @@
+package org.apache.mesos.chronos.scheduler.mesos
+
+import mesosphere.mesos.protos._
+import org.apache.mesos.chronos.scheduler.jobs.constraints.ConstraintSpecHelper
+import org.apache.mesos.Protos
+import java.util.logging.Logger
+import org.specs2.mock.Mockito
+import org.specs2.mutable.SpecificationWithJUnit
+import org.apache.mesos.chronos.scheduler.jobs.constraints.LikeConstraint
+import org.apache.mesos.chronos.scheduler.jobs.constraints.EqualsConstraint
+import mesosphere.mesos.protos.Implicits._
+import org.specs2.specification.BeforeEach
+
+/**
+ * spec for testing ConstraintChecker
+ *
+ * @author tony kerz (anthony.kerz@gmail.com)
+ */
+class ConstraintCheckerSpec extends SpecificationWithJUnit 
+with Mockito 
+with ConstraintSpecHelper 
+{
+  isolated
+
+  val offer = Protos.Offer.newBuilder()
+  .setId(OfferID("1"))
+  .setFrameworkId(FrameworkID("chronos"))
+  .setSlaveId(SlaveID("slave-1"))
+  .setHostname("slave.one.com")
+  .addAttributes(createTextAttribute("rack", "rack-1"))
+  .build()
+
+   val offerWithHostname = Protos.Offer.newBuilder()
+  .setId(OfferID("1"))
+  .setFrameworkId(FrameworkID("chronos"))
+  .setSlaveId(SlaveID("slave-1"))
+  .setHostname("slave.one.com")
+  .addAttributes(createTextAttribute("hostname", "slave.explicit.com"))
+  .build()
+
+  val constraintChecker = new ConstraintChecker()
+
+  "check constraints" should {
+
+    "be true when equal" in {
+      val constraints = Seq(EqualsConstraint("rack", "rack-1"))
+      constraintChecker.checkConstraints(offer, constraints) must beTrue
+    }
+
+    "be false when not equal" in {
+      val constraints = Seq(EqualsConstraint("rack", "rack-2"))
+      constraintChecker.checkConstraints(offer, constraints) must beFalse
+    }
+
+    "be true when like" in {
+      val constraints = Seq(LikeConstraint("rack", "rack-[1-3]"))
+      constraintChecker.checkConstraints(offer, constraints) must beTrue
+    }
+
+    "be false when not like" in {
+      val constraints = Seq(LikeConstraint("rack", "rack-[2-3]"))
+      constraintChecker.checkConstraints(offer, constraints) must beFalse
+    }
+
+    "be true when hostname equal" in {
+      val constraints = Seq(EqualsConstraint("hostname", "slave.one.com"))
+      constraintChecker.checkConstraints(offer, constraints) must beTrue
+    }
+
+    "be false when hostname not equal" in {
+      val constraints = Seq(EqualsConstraint("hostname", "slave.two.com"))
+      constraintChecker.checkConstraints(offer, constraints) must beFalse
+    }
+
+    "be false when hostname explicitly set to something else and not equal" in {
+      val constraints = Seq(EqualsConstraint("hostname", "slave.one.com"))
+      constraintChecker.checkConstraints(offerWithHostname, constraints) must beFalse
+    }
+
+    "be true when hostname explicitly set to something else and equal" in {
+      val constraints = Seq(EqualsConstraint("hostname", "slave.explicit.com"))
+      constraintChecker.checkConstraints(offerWithHostname, constraints) must beTrue
+    }
+  }
+}