Allocation consistency between model versions

29 files changed, 211 insertions, 172 deletions

diff --git a/config-application-package/src/test/java/com/yahoo/config/application/OverrideProcessorTest.java b/config-application-package/src/test/java/com/yahoo/config/application/OverrideProcessorTest.java
index b80372ec9ff..32a1c4f847f 100644
--- a/config-application-package/src/test/java/com/yahoo/config/application/OverrideProcessorTest.java
+++ b/config-application-package/src/test/java/com/yahoo/config/application/OverrideProcessorTest.java
@@ -15,8 +15,7 @@ import java.io.IOException;
 import java.io.StringReader;
 
 /**
- * @author lulf
- * @since 5.22
+ * @author Ulf Lilleengen
  */
 public class OverrideProcessorTest {
 
diff --git a/config-model-api/src/main/java/com/yahoo/config/application/api/ApplicationFile.java b/config-model-api/src/main/java/com/yahoo/config/application/api/ApplicationFile.java
index bcc8d222ca5..0384a5c7a1c 100644
--- a/config-model-api/src/main/java/com/yahoo/config/application/api/ApplicationFile.java
+++ b/config-model-api/src/main/java/com/yahoo/config/application/api/ApplicationFile.java
@@ -11,7 +11,7 @@ import java.util.List;
  * An application file represents a file within an application package. This class can be used to traverse the entire
  * application package file structure, as well as read and write files to it, and create directories.
  *
- * @author Ulf Lillengen
+ * @author Ulf Lilleengen
  */
 public abstract class ApplicationFile implements Comparable<ApplicationFile> {
 
diff --git a/config-model-api/src/main/java/com/yahoo/config/application/api/ApplicationPackage.java b/config-model-api/src/main/java/com/yahoo/config/application/api/ApplicationPackage.java
index 795e87b7690..23bbdd511b7 100644
--- a/config-model-api/src/main/java/com/yahoo/config/application/api/ApplicationPackage.java
+++ b/config-model-api/src/main/java/com/yahoo/config/application/api/ApplicationPackage.java
@@ -228,10 +228,22 @@ public interface ApplicationPackage {
         throw new UnsupportedOperationException("This application package cannot write its metadata");
     }
 
+    /** 
+     * Returns the single host allocation info of this, or an empty map if no allocation is available 
+     * 
+     * @deprecated please use #getProvisionInfo
+     */
+    // TODO: Remove on Vespa 7
+    @Deprecated
     default Map<Version, ProvisionInfo> getProvisionInfoMap() {
         return Collections.emptyMap();
     }
 
+    /** Returns the host allocation info of this, or empty if no allocation is available */
+    default Optional<ProvisionInfo> getProvisionInfo() {
+        return Optional.empty();
+    }
+
     default Map<Version, FileRegistry> getFileRegistryMap() {
         return Collections.emptyMap();
     }
diff --git a/config-model-api/src/main/java/com/yahoo/config/model/api/Model.java b/config-model-api/src/main/java/com/yahoo/config/model/api/Model.java
index 0c038077fe4..db589ef5d21 100644
--- a/config-model-api/src/main/java/com/yahoo/config/model/api/Model.java
+++ b/config-model-api/src/main/java/com/yahoo/config/model/api/Model.java
@@ -16,8 +16,7 @@ import java.util.Collection;
  * A {@link Model} represents the interface towards the model of an entire tenant, and defines methods
  * for querying this model.
  *
- * @author lulf
- * @since 5.1
+ * @author Ulf Lilleengen
  */
 public interface Model {
 
@@ -60,9 +59,20 @@ public interface Model {
 
     /**
      * Get the provisioning info for this model.
+     * 
      * @return {@link ProvisionInfo} instance, if available.
+     * @deprecated use provisionInfo
      */
-    Optional<ProvisionInfo> getProvisionInfo();
+    @Deprecated
+    // TODO: Remove this (and the implementation below) when no version older than 6.142 is deployed anywhere
+    default Optional<ProvisionInfo> getProvisionInfo() {
+        return Optional.of(provisionInfo());
+    }
+
+    @SuppressWarnings("deprecation")
+    default ProvisionInfo provisionInfo() {
+        return getProvisionInfo().get();
+    }
 
     /**
      * Returns whether this application allows serving config request for a different version.
@@ -71,11 +81,6 @@ public interface Model {
      */
     default boolean allowModelVersionMismatch(Instant now) { return false; }
 
-    /** @deprecated pass now. */
-    // TODO: Remove this when no version older than 6.115 is deployed anywhere
-    @Deprecated
-    default boolean allowModelVersionMismatch() { return allowModelVersionMismatch(Clock.systemUTC().instant()); }
-
     /**
      * Returns whether old config models should be loaded (default) or not.
      * Skipping old config models is a validation override which is useful when the old model
@@ -88,9 +93,4 @@ public interface Model {
      */
     default boolean skipOldConfigModels(Instant now) { return false; }
     
-    /** @deprecated pass now. */
-    // TODO: Remove this when no version older than 6.115 is deployed anywhere
-    @Deprecated 
-    default boolean skipOldConfigModels() { return skipOldConfigModels(Clock.systemUTC().instant()); }
-
 }
diff --git a/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java b/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
index 5afc570d81b..5b79415c132 100644
--- a/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
+++ b/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
@@ -17,7 +17,7 @@ import java.util.Set;
 /**
  * Model context containing state provided to model factories.
  *
- * @author lulf
+ * @author Ulf Lilleengen
  */
 public interface ModelContext {
 
@@ -31,11 +31,6 @@ public interface ModelContext {
     Properties properties();
     default Optional<File> appDir() { return Optional.empty();}
     
-    /** @deprecated TODO: Remove this when no config models older than 6.98 are used */
-    @SuppressWarnings("unused")
-    @Deprecated
-    default Optional<com.yahoo.config.provision.Version> vespaVersion() { return Optional.empty(); }
-    
     /** The Vespa version this model is built for */
     Version modelVespaVersion();
     
@@ -50,4 +45,5 @@ public interface ModelContext {
         Zone zone();
         Set<Rotation> rotations();
     }
+
 }
diff --git a/config-model/src/main/java/com/yahoo/config/model/test/MockApplicationPackage.java b/config-model/src/main/java/com/yahoo/config/model/test/MockApplicationPackage.java
index 133d94c745b..8b97eb2503e 100644
--- a/config-model/src/main/java/com/yahoo/config/model/test/MockApplicationPackage.java
+++ b/config-model/src/main/java/com/yahoo/config/model/test/MockApplicationPackage.java
@@ -25,6 +25,7 @@ import java.util.*;
  * @author tonytv
  */
 public class MockApplicationPackage implements ApplicationPackage {
+
     public static final String MUSIC_SEARCHDEFINITION = createSearchDefinition("music", "foo");
     public static final String BOOK_SEARCHDEFINITION = createSearchDefinition("book", "bar");
 
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/HostResource.java b/config-model/src/main/java/com/yahoo/vespa/model/HostResource.java
index bc890755ca9..5e74a2ebc8a 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/HostResource.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/HostResource.java
@@ -22,7 +22,7 @@ import java.util.stream.Collectors;
  * TODO: Merge with {@link Host}
  * Host resources are ordered by their host order.
  *
- * @author Ulf Lillengen
+ * @author Ulf Lilleengen
  */
 public class HostResource implements Comparable<HostResource> {
 
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/VespaModel.java b/config-model/src/main/java/com/yahoo/vespa/model/VespaModel.java
index c61435ca831..d790e5c67b5 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/VespaModel.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/VespaModel.java
@@ -83,7 +83,7 @@ public final class VespaModel extends AbstractConfigProducerRoot implements Seri
 
     public static final Logger log = Logger.getLogger(VespaModel.class.getPackage().toString());
     private ConfigModelRepo configModelRepo = new ConfigModelRepo();
-    private final Optional<ProvisionInfo> info;
+    private final ProvisionInfo provisionInfo;
 
     /**
      * The config id for the root config producer
@@ -146,7 +146,7 @@ public final class VespaModel extends AbstractConfigProducerRoot implements Seri
         if (complete) { // create a a completed, frozen model
             configModelRepo.readConfigModels(deployState, builder, root, configModelRegistry);
             addServiceClusters(deployState.getApplicationPackage(), builder);
-            this.info = Optional.of(createProvisionInfo()); // must happen after the two lines above
+            this.provisionInfo = ProvisionInfo.withHosts(root.getHostSystem().getHostSpecs()); // must happen after the two lines above
             setupRouting();
             this.fileDistributor = root.getFileDistributionConfigProducer().getFileDistributor();
             getAdmin().addPerHostServices(getHostSystem().getHosts(), deployState.getProperties());
@@ -157,7 +157,7 @@ public final class VespaModel extends AbstractConfigProducerRoot implements Seri
             this.deployState = null;
         }
         else { // create a model with no services instantiated and the given file distributor
-            this.info = Optional.of(createProvisionInfo());
+            this.provisionInfo = ProvisionInfo.withHosts(root.getHostSystem().getHostSpecs());
             this.fileDistributor = fileDistributor;
         }
     }
@@ -167,10 +167,6 @@ public final class VespaModel extends AbstractConfigProducerRoot implements Seri
         return new VespaModel(new NullConfigModelRegistry(), deployState, false, new FileDistributor(deployState.getFileRegistry()));
     }
 
-    private ProvisionInfo createProvisionInfo() {
-        return ProvisionInfo.withHosts(root.getHostSystem().getHostSpecs());
-    }
-
     private void validateWrapExceptions() {
         try {
             validate();
@@ -421,8 +417,8 @@ public final class VespaModel extends AbstractConfigProducerRoot implements Seri
     }
 
     @Override
-    public Optional<ProvisionInfo> getProvisionInfo() {
-        return info;
+    public ProvisionInfo provisionInfo() {
+        return provisionInfo;
     }
 
     private static Set<ConfigKey<?>> configsProduced(ConfigProducer cp) {
diff --git a/config-model/src/test/java/com/yahoo/vespa/model/test/VespaModelTestCase.java b/config-model/src/test/java/com/yahoo/vespa/model/test/VespaModelTestCase.java
index 8102f358830..b35acffaf06 100644
--- a/config-model/src/test/java/com/yahoo/vespa/model/test/VespaModelTestCase.java
+++ b/config-model/src/test/java/com/yahoo/vespa/model/test/VespaModelTestCase.java
@@ -286,7 +286,7 @@ public class VespaModelTestCase {
                         .build())
                 .build();
         VespaModel model = new VespaModel(new NullConfigModelRegistry(), deployState);
-        ProvisionInfo info = model.getProvisionInfo().get();
+        ProvisionInfo info = model.provisionInfo();
         assertEquals("Admin version 3 is ignored, and there are no other hosts to borrow for admin services", 0, info.getHosts().size());
     }
 
diff --git a/config-provisioning/src/main/java/com/yahoo/config/provision/HostSpec.java b/config-provisioning/src/main/java/com/yahoo/config/provision/HostSpec.java
index 5d6b3fcaca4..a94660e142e 100644
--- a/config-provisioning/src/main/java/com/yahoo/config/provision/HostSpec.java
+++ b/config-provisioning/src/main/java/com/yahoo/config/provision/HostSpec.java
@@ -5,11 +5,13 @@ import com.google.common.collect.ImmutableList;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 import java.util.Optional;
 
 /**
  * A specification of a host and its role.
- * The identity of a host is determined by its name.
+ * This is a value object: Immutable and the identity is determined by all the content.
+ * Host specs are ordered by host name.
  *
  * @author hmusum
  */
@@ -19,7 +21,7 @@ public class HostSpec implements Comparable<HostSpec> {
     private final String hostname;
 
     /** Aliases of this host */
-    private final List<String> aliases;
+    private final ImmutableList<String> aliases;
 
     /** The current membership role of this host in the cluster it belongs to */
     private final Optional<ClusterMembership> membership;
@@ -70,14 +72,20 @@ public class HostSpec implements Comparable<HostSpec> {
 
     @Override
     public boolean equals(Object o) {
+        if (o == this) return true;
         if ( ! (o instanceof HostSpec)) return false;
+
         HostSpec other = (HostSpec) o;
-        return this.hostname().equals(other.hostname());
+        if ( ! this.hostname.equals(other.hostname)) return false;
+        if ( ! this.aliases.equals(other.aliases)) return false;
+        if ( ! this.membership.equals(other.membership)) return false;
+        if ( ! this.flavor.equals(other.flavor)) return false;
+        return true;
     }
 
     @Override
     public int hashCode() {
-        return hostname.hashCode();
+        return Objects.hash(hostname, aliases, membership, flavor); 
     }
 
     @Override
diff --git a/config-provisioning/src/main/java/com/yahoo/config/provision/ProvisionInfo.java b/config-provisioning/src/main/java/com/yahoo/config/provision/ProvisionInfo.java
index 8bef1f7c9b7..4506f52e085 100644
--- a/config-provisioning/src/main/java/com/yahoo/config/provision/ProvisionInfo.java
+++ b/config-provisioning/src/main/java/com/yahoo/config/provision/ProvisionInfo.java
@@ -1,6 +1,7 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.config.provision;
 
+import com.google.common.collect.ImmutableSet;
 import com.yahoo.slime.ArrayTraverser;
 import com.yahoo.slime.Cursor;
 import com.yahoo.slime.Inspector;
@@ -14,10 +15,12 @@ import java.util.Optional;
 import java.util.Set;
 
 /**
- * Information about hosts provisioned for an application, and (de)serialization of this information to/from JSON.
+ * The hosts allocated to an application (a better name would be "AllocatedHosts").
+ * This can be serialized to/from JSON.
+ * This is immutable.
  *
- * @author lulf
- * @since 5.12
+ * @author Ulf Lilleengen
+ * @author bratseth
  */
 public class ProvisionInfo {
 
@@ -28,10 +31,10 @@ public class ProvisionInfo {
     private static final String hostSpecFlavor = "flavor";
     private static final String hostSpecVespaVersion = "vespaVersion";
 
-    private final Set<HostSpec> hosts = new LinkedHashSet<>();
+    private final ImmutableSet<HostSpec> hosts;
 
     private ProvisionInfo(Set<HostSpec> hosts) {
-        this.hosts.addAll(hosts);
+        this.hosts = ImmutableSet.copyOf(hosts);
     }
 
     public static ProvisionInfo withHosts(Set<HostSpec> hosts) {
@@ -40,13 +43,11 @@ public class ProvisionInfo {
 
     private void toSlime(Cursor cursor) {
         Cursor array = cursor.setArray(mappingKey);
-        for (HostSpec host : hosts) {
-            Cursor object = array.addObject();
-            serializeHostSpec(object.setObject(hostSpecKey), host);
-        }
+        for (HostSpec host : hosts)
+            toSlime(host, array.addObject().setObject(hostSpecKey));
     }
 
-    private void serializeHostSpec(Cursor cursor, HostSpec host) {
+    private void toSlime(HostSpec host, Cursor cursor) {
         cursor.setString(hostSpecHostName, host.hostname());
         if (host.membership().isPresent()) {
             cursor.setString(hostSpecMembership, host.membership().get().stringValue());
@@ -56,9 +57,8 @@ public class ProvisionInfo {
             cursor.setString(hostSpecFlavor, host.flavor().get().name());
     }
 
-    public Set<HostSpec> getHosts() {
-        return Collections.unmodifiableSet(hosts);
-    }
+    /** Returns the hosts of this allocation */
+    public Set<HostSpec> getHosts() { return hosts; }
 
     private static ProvisionInfo fromSlime(Inspector inspector, Optional<NodeFlavors> nodeFlavors) {
         Inspector array = inspector.field(mappingKey);
@@ -66,27 +66,27 @@ public class ProvisionInfo {
         array.traverse(new ArrayTraverser() {
             @Override
             public void entry(int i, Inspector inspector) {
-                hosts.add(deserializeHostSpec(inspector.field(hostSpecKey), nodeFlavors));
+                hosts.add(hostsFromSlime(inspector.field(hostSpecKey), nodeFlavors));
             }
         });
         return new ProvisionInfo(hosts);
     }
 
-    private static HostSpec deserializeHostSpec(Inspector object, Optional<NodeFlavors> nodeFlavors) {
+    private static HostSpec hostsFromSlime(Inspector object, Optional<NodeFlavors> nodeFlavors) {
         Optional<ClusterMembership> membership =
-                object.field(hostSpecMembership).valid() ? Optional.of(readMembership(object)) : Optional.empty();
+                object.field(hostSpecMembership).valid() ? Optional.of(membershipFromSlime(object)) : Optional.empty();
         Optional<Flavor> flavor =
-                object.field(hostSpecFlavor).valid() ? readFlavor(object, nodeFlavors) : Optional.empty();
+                object.field(hostSpecFlavor).valid() ? flavorFromSlime(object, nodeFlavors) : Optional.empty();
 
         return new HostSpec(object.field(hostSpecHostName).asString(),Collections.emptyList(), flavor, membership);
     }
 
-    private static ClusterMembership readMembership(Inspector object) {
+    private static ClusterMembership membershipFromSlime(Inspector object) {
         return ClusterMembership.from(object.field(hostSpecMembership).asString(),
                                       com.yahoo.component.Version.fromString(object.field(hostSpecVespaVersion).asString()));
     }
 
-    private static Optional<Flavor> readFlavor(Inspector object, Optional<NodeFlavors> nodeFlavors) {
+    private static Optional<Flavor> flavorFromSlime(Inspector object, Optional<NodeFlavors> nodeFlavors) {
         return nodeFlavors.map(flavorMapper ->  flavorMapper.getFlavor(object.field(hostSpecFlavor).asString()))
                 .orElse(Optional.empty());
     }
@@ -100,12 +100,17 @@ public class ProvisionInfo {
     public static ProvisionInfo fromJson(byte[] json, Optional<NodeFlavors> nodeFlavors) {
         return fromSlime(SlimeUtils.jsonToSlime(json).get(), nodeFlavors);
     }
-
-    public ProvisionInfo merge(ProvisionInfo provisionInfo) {
-        Set<HostSpec> mergedSet = new LinkedHashSet<>();
-        mergedSet.addAll(this.hosts);
-        mergedSet.addAll(provisionInfo.getHosts());
-        return ProvisionInfo.withHosts(mergedSet);
+    
+    @Override
+    public boolean equals(Object other) {
+        if (other == this) return true;
+        if ( ! (other instanceof ProvisionInfo)) return false;
+        return ((ProvisionInfo) other).hosts.equals(this.hosts);
+    }
+    
+    @Override
+    public int hashCode() {
+        return hosts.hashCode();
     }
 
 }
diff --git a/config-provisioning/src/test/java/com/yahoo/config/provision/ProvisionInfoTest.java b/config-provisioning/src/test/java/com/yahoo/config/provision/ProvisionInfoTest.java
index 4fa69eb77e0..435b6e3a28a 100644
--- a/config-provisioning/src/test/java/com/yahoo/config/provision/ProvisionInfoTest.java
+++ b/config-provisioning/src/test/java/com/yahoo/config/provision/ProvisionInfoTest.java
@@ -13,8 +13,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 /**
- * @author lulf
- * @since 5.12
+ * @author Ulf Lilleengen
  */
 public class ProvisionInfoTest {
 
@@ -32,19 +31,6 @@ public class ProvisionInfoTest {
         assertProvisionInfo(info);
     }
 
-    @Test
-    public void testProvisionInfoMerging() throws IOException {
-        Set<HostSpec> hostsA = new LinkedHashSet<>(Collections.singleton(h1));
-        Set<HostSpec> hostsB = new LinkedHashSet<>();
-        hostsB.add(h2);
-        hostsB.add(h3);
-
-        ProvisionInfo infoA = ProvisionInfo.withHosts(hostsA);
-        ProvisionInfo infoB = ProvisionInfo.withHosts(hostsB);
-        assertProvisionInfo(infoA.merge(infoB));
-        assertProvisionInfo(infoB.merge(infoA));
-    }
-
     private void assertProvisionInfo(ProvisionInfo info) throws IOException {
         ProvisionInfo serializedInfo = ProvisionInfo.fromJson(info.toJson(), Optional.empty());
         assertEquals(info.getHosts().size(), serializedInfo.getHosts().size());
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClient.java b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClient.java
index ea278596e80..b2bcba94662 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClient.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClient.java
@@ -25,7 +25,6 @@ import java.util.*;
  * A class used for reading and writing application data to zookeeper.
  *
  * @author hmusum
- * @since 5.1
  */
 public class ZooKeeperClient {
 
@@ -356,9 +355,8 @@ public class ZooKeeperClient {
         }
     }
 
-    private void feedProvisionInfo(Version version, ProvisionInfo info) throws IOException {
-        byte[] json = info.toJson();
-        configCurator.putData(rootPath.append(ZKApplicationPackage.allocatedHostsNode).append(version.toSerializedForm()).getAbsolute(), json);
+    public void feedProvisionInfo(ProvisionInfo info) throws IOException {
+        configCurator.putData(rootPath.append(ZKApplicationPackage.allocatedHostsNode).getAbsolute(), info.toJson());
     }
 
     public void feedZKFileRegistries(Map<Version, FileRegistry> fileRegistryMap) {
@@ -367,9 +365,4 @@ public class ZooKeeperClient {
         }
     }
 
-    public void feedProvisionInfos(Map<Version, ProvisionInfo> provisionInfoMap) throws IOException {
-        for (Map.Entry<Version, ProvisionInfo> versionProvisionInfoEntry : provisionInfoMap.entrySet()) {
-            feedProvisionInfo(versionProvisionInfoEntry.getKey(), versionProvisionInfoEntry.getValue());
-        }
-    }
 }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperDeployer.java b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperDeployer.java
index 246d7226cfd..9c0d7f69d19 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperDeployer.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperDeployer.java
@@ -14,7 +14,6 @@ import java.util.Map;
  * Initialize must be called before each deploy.
  *
  * @author lulf
- * @since 5.1
  */
 public class ZooKeeperDeployer {
 
@@ -28,15 +27,16 @@ public class ZooKeeperDeployer {
      * Deploys an application package to zookeeper. initialize() must be called before calling this method.
      *
      * @param applicationPackage The application package to persist.
-     * @param fileRegistryMap The file registries to persist.
-     * @param provisionInfoMap The provisioning infos to persist.
+     * @param fileRegistryMap the file registries to persist.
+     * @param provisionInfo the provisioning info to persist.
      * @throws IOException if deploying fails
      */
-    public void deploy(ApplicationPackage applicationPackage, Map<Version, FileRegistry> fileRegistryMap, Map<Version, ProvisionInfo> provisionInfoMap) throws IOException {
+    public void deploy(ApplicationPackage applicationPackage, Map<Version, FileRegistry> fileRegistryMap, 
+                       ProvisionInfo provisionInfo) throws IOException {
         zooKeeperClient.setupZooKeeper();
         zooKeeperClient.feedZooKeeper(applicationPackage);
         zooKeeperClient.feedZKFileRegistries(fileRegistryMap);
-        zooKeeperClient.feedProvisionInfos(provisionInfoMap);
+        zooKeeperClient.feedProvisionInfo(provisionInfo);
     }
 
     public void cleanup() {
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/modelfactory/ActivatedModelsBuilder.java b/configserver/src/main/java/com/yahoo/vespa/config/server/modelfactory/ActivatedModelsBuilder.java
index a805d335c2e..86187a08d17 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/modelfactory/ActivatedModelsBuilder.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/modelfactory/ActivatedModelsBuilder.java
@@ -87,7 +87,7 @@ public class ActivatedModelsBuilder extends ModelsBuilder<Application> {
                 logger,
                 configDefinitionRepo,
                 getForVersionOrLatest(applicationPackage.getFileRegistryMap(), modelFactory.getVersion()).orElse(new MockFileRegistry()),
-                createHostProvisioner(getForVersionOrLatest(applicationPackage.getProvisionInfoMap(), modelFactory.getVersion())),
+                createHostProvisioner(applicationPackage.getProvisionInfo()),
                 createModelContextProperties(applicationId),
                 Optional.empty(),
                 new com.yahoo.component.Version(modelFactory.getVersion().toString()),
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/session/LocalSession.java b/configserver/src/main/java/com/yahoo/vespa/config/server/session/LocalSession.java
index a222182f87a..0b8f1f67e79 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/session/LocalSession.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/session/LocalSession.java
@@ -30,8 +30,7 @@ import java.util.Optional;
  * prepared. Deleting a local session will ensure that the local filesystem state and global zookeeper state is
  * cleaned for this session.
  *
- * @author lulf
- * @since 5.1
+ * @author Ulf Lilleengen
  */
 // This is really the store of an application, whether it is active or in an edit session
 // TODO: Separate the "application store" and "session" aspects - the latter belongs in the HTTP layer
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionPreparer.java b/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionPreparer.java
index 0b76c57e142..3b96069c4e7 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionPreparer.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionPreparer.java
@@ -42,8 +42,7 @@ import javax.xml.transform.TransformerException;
 /**
  * A SessionPreparer is responsible for preparing a session given an application package.
  *
- * @author lulf
- * @since 5.1
+ * @author Ulf Lilleengen
  */
 public class SessionPreparer {
 
@@ -195,7 +194,7 @@ public class SessionPreparer {
                                   vespaVersion,
                                   logger,
                                   prepareResult.getFileRegistries(), 
-                                  prepareResult.getProvisionInfos());
+                                  prepareResult.getProvisionInfo());
             checkTimeout("write state to zookeeper");
         }
 
@@ -236,10 +235,10 @@ public class SessionPreparer {
                                        com.yahoo.component.Version vespaVersion,
                                        DeployLogger deployLogger,
                                        Map<Version, FileRegistry> fileRegistryMap,
-                                       Map<Version, ProvisionInfo> provisionInfoMap) {
+                                       ProvisionInfo provisionInfo) {
         ZooKeeperDeployer zkDeployer = zooKeeperClient.createDeployer(deployLogger);
         try {
-            zkDeployer.deploy(applicationPackage, fileRegistryMap, provisionInfoMap);
+            zkDeployer.deploy(applicationPackage, fileRegistryMap, provisionInfo);
             zooKeeperClient.writeApplicationId(applicationId);
             zooKeeperClient.writeVespaVersion(vespaVersion);
         } catch (RuntimeException | IOException e) {
@@ -252,19 +251,20 @@ public class SessionPreparer {
     private static class PrepareResult {
 
         private final ImmutableList<PreparedModelsBuilder.PreparedModelResult> results;
+        
+        private final ReconciliatedHostAllocations reconciliatedHostAllocations;
 
         public PrepareResult(List<PreparedModelsBuilder.PreparedModelResult> results) {
             this.results = ImmutableList.copyOf(results);
+            reconciliatedHostAllocations = new ReconciliatedHostAllocations(results);
         }
 
         /** Returns the results for each model as an immutable list */
         public List<PreparedModelsBuilder.PreparedModelResult> asList() { return results; }
 
-        public Map<Version, ProvisionInfo> getProvisionInfos() {
-            return results.stream()
-                    .filter(result -> result.model.getProvisionInfo().isPresent())
-                    .collect(Collectors.toMap((prepareResult -> prepareResult.version),
-                            (prepareResult -> prepareResult.model.getProvisionInfo().get())));
+        /** Returns the host allocations resulting from this preparation. */
+        public ProvisionInfo getProvisionInfo() {
+            return reconciliatedHostAllocations.allocatedHosts();
         }
 
         public Map<Version, FileRegistry> getFileRegistries() {
@@ -290,4 +290,31 @@ public class SessionPreparer {
 
     }
 
+    /**
+     * During model building each model version will request nodes allocated (from the node allocator)
+     * for each cluster specified by that model. As allocations are stable this should usually
+     * result in the same allocations for the same clusters across all model versions,
+     * otherwise we should fail this preparation as such inconsistencies lead to undefined behavior,
+     * and there is really just one true allocation (for a given cluster) to be activated in the node repository.
+     * 
+     * However, these disagreements between allocations in each model version are allowed:
+     * - A node may be retired in some model version but not another. This allows model versions to change cluster sizes,
+     *   and is ok because the system will converge on the latest version's opinion
+     * - Clusters may be present on some version but not on another. This does not lead to inconsistency
+     *   and allows new model versions to introduce new clusters.
+     *   
+     * For each cluster, the newest model version which has that cluster decides the correct retirement status of nodes
+     * (and all model versions having the cluster must have the same nodes).
+     * 
+     * This class ensures these constraints and returns a reconciliated set of nodes which should be activated,
+     * given a set of model activation results.
+     */
+    private static final class ReconciliatedHostAllocations {
+        
+        public ReconciliatedHostAllocations(List<PreparedModelsBuilder.PreparedModelResult> results) {
+            
+        }
+
+    }
+    
 }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionZooKeeperClient.java b/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionZooKeeperClient.java
index a677c5cb7f9..3bd60d3d96c 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionZooKeeperClient.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionZooKeeperClient.java
@@ -190,9 +190,8 @@ public class SessionZooKeeperClient {
     }
 
     ProvisionInfo getProvisionInfo() {
-        return loadApplicationPackage().getProvisionInfoMap().values().stream()
-                .reduce((infoA, infoB) -> infoA.merge(infoB))
-                .orElseThrow(() -> new IllegalStateException("Trying to read provision info, but no provision info exists"));
+        return loadApplicationPackage().getProvisionInfo()
+                                       .orElseThrow(() -> new IllegalStateException("Provision info does not exists"));
     }
 
     public ZooKeeperDeployer createDeployer(DeployLogger logger) {
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ConfigCurator.java b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ConfigCurator.java
index 80c1c44546f..c09fe5ae4bb 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ConfigCurator.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ConfigCurator.java
@@ -146,7 +146,7 @@ public class ConfigCurator {
     /**
      * Returns the data at a path, or null if the path does not exist.
      *
-     * @param path    a String with a pathname.
+     * @param path a String with a pathname.
      * @return a byte array with data.
      */
     public byte[] getBytes(String path) {
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java
index 4f591278a38..4aa4fc32483 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java
@@ -2,6 +2,7 @@
 package com.yahoo.vespa.config.server.zookeeper;
 
 import com.google.common.base.Joiner;
+import com.yahoo.component.Version;
 import com.yahoo.config.application.api.ApplicationMetaData;
 import com.yahoo.config.application.api.ComponentInfo;
 import com.yahoo.config.application.api.FileRegistry;
@@ -12,7 +13,6 @@ import com.yahoo.config.application.api.ApplicationPackage;
 import com.yahoo.config.model.application.provider.*;
 import com.yahoo.config.provision.NodeFlavors;
 import com.yahoo.config.provision.ProvisionInfo;
-import com.yahoo.config.provision.Version;
 import com.yahoo.io.IOUtils;
 import com.yahoo.path.Path;
 import com.yahoo.io.reader.NamedReader;
@@ -24,7 +24,13 @@ import com.yahoo.vespa.config.util.ConfigUtils;
 import java.io.File;
 import java.io.Reader;
 import java.io.StringReader;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
 
 /**
  * Represents an application residing in zookeeper.
@@ -35,9 +41,9 @@ public class ZKApplicationPackage implements ApplicationPackage {
 
     private ZKLiveApp liveApp;
 
-    private final Map<Version, PreGeneratedFileRegistry> fileRegistryMap = new HashMap<>();
-    private final Map<Version, ProvisionInfo> provisionInfoMap = new HashMap<>();
-    private static final Version legacyVersion = Version.fromIntValues(0, 0, 0);
+    private final Map<com.yahoo.config.provision.Version, PreGeneratedFileRegistry> fileRegistryMap = new HashMap<>();
+    private final Optional<ProvisionInfo> provisionInfo;
+    private static final com.yahoo.config.provision.Version legacyVersion = com.yahoo.config.provision.Version.fromIntValues(0, 0, 0);
 
     public static final String fileRegistryNode = "fileregistry";
     public static final String allocatedHostsNode = "allocatedHosts";
@@ -48,32 +54,54 @@ public class ZKApplicationPackage implements ApplicationPackage {
         liveApp = new ZKLiveApp(zk, appPath);
         metaData = readMetaDataFromLiveApp(liveApp);
         importFileRegistries(fileRegistryNode);
-        importProvisionInfos(allocatedHostsNode, nodeFlavors);
+        provisionInfo = importProvisionInfos(allocatedHostsNode, nodeFlavors);
     }
 
-    private void importProvisionInfos(String allocatedHostsNode, Optional<NodeFlavors> nodeFlavors) {
-        List<String> provisionInfoNodes = liveApp.getChildren(allocatedHostsNode);
-        if (provisionInfoNodes.isEmpty()) {
-            Optional<ProvisionInfo> provisionInfo = importProvisionInfo(allocatedHostsNode, nodeFlavors);
-            provisionInfo.ifPresent(info -> provisionInfoMap.put(legacyVersion, info));
-        } else {
-            provisionInfoNodes.stream()
-                    .forEach(versionStr -> {
-                        Version version = Version.fromString(versionStr);
-                        Optional<ProvisionInfo> provisionInfo = importProvisionInfo(Joiner.on("/").join(allocatedHostsNode, versionStr),
-                                                                                    nodeFlavors);
-                        provisionInfo.ifPresent(info -> provisionInfoMap.put(version, info));
-                    });
+    private Optional<ProvisionInfo> importProvisionInfos(String allocatedHostsPath, Optional<NodeFlavors> nodeFlavors) {
+        if ( ! liveApp.exists(allocatedHostsPath)) return Optional.empty();
+        Optional<ProvisionInfo> provisionInfo = readProvisionInfo(allocatedHostsPath, nodeFlavors);
+        if ( ! provisionInfo.isPresent()) { // Read from legacy location. TODO: Remove when 6.142 is in production everywhere
+            List<String> provisionInfoByVersionNodes = liveApp.getChildren(allocatedHostsPath);
+            provisionInfo = newestOf(readProvisionInfosByVersion(provisionInfoByVersionNodes, nodeFlavors));
         }
+        return provisionInfo;
+    }
+    
+    private Map<Version, ProvisionInfo> readProvisionInfosByVersion(List<String> provisionInfoByVersionNodes, Optional<NodeFlavors> nodeFlavors) {
+        Map<Version, ProvisionInfo> provisionInfoMap = new HashMap<>();
+        provisionInfoByVersionNodes.stream()
+                .forEach(versionStr -> {
+                    Version version = Version.fromString(versionStr);
+                    Optional<ProvisionInfo> provisionInfo = readProvisionInfo(Joiner.on("/").join(allocatedHostsNode, versionStr),
+                                                                              nodeFlavors);
+                    provisionInfo.ifPresent(info -> provisionInfoMap.put(version, info));
+                });
+        return provisionInfoMap;
     }
 
-    private Optional<ProvisionInfo> importProvisionInfo(String provisionInfoNode, Optional<NodeFlavors> nodeFlavors) {
-        try {
-            if (liveApp.exists(provisionInfoNode)) {
-                return Optional.of(ProvisionInfo.fromJson(liveApp.getBytes(provisionInfoNode), nodeFlavors));
-            } else {
-                return Optional.empty();
+    private Optional<ProvisionInfo> newestOf(Map<Version, ProvisionInfo> provisionInfoMap) {
+        if (provisionInfoMap.isEmpty()) return Optional.empty();
+        Version newestVersion = null;
+        ProvisionInfo newestInfo = null;
+        for (Map.Entry<Version, ProvisionInfo> entry : provisionInfoMap.entrySet()) {
+            if (newestVersion == null || newestVersion.isBefore(entry.getKey())) {
+                newestVersion = entry.getKey();
+                newestInfo = entry.getValue();
             }
+        }
+        return Optional.of(newestInfo);
+    }
+
+    /** 
+     * Reads provision info at the given node.
+     * 
+     * @return the provision info at this node or empty if there is no data at this path
+     */
+    private Optional<ProvisionInfo> readProvisionInfo(String provisionInfoPath, Optional<NodeFlavors> nodeFlavors) {
+        try {
+            byte[] data = liveApp.getBytes(provisionInfoPath);
+            if (data.length == 0) return Optional.empty(); // TODO: Remove this line (and make return non-optional) when 6.142 is in production everywhere
+            return Optional.of(ProvisionInfo.fromJson(data, nodeFlavors));
         } catch (Exception e) {
             throw new RuntimeException("Unable to read provision info", e);
         }
@@ -85,9 +113,9 @@ public class ZKApplicationPackage implements ApplicationPackage {
             fileRegistryMap.put(legacyVersion, importFileRegistry(fileRegistryNode));
         } else {
             fileRegistryNodes.stream()
-                    .forEach(versionStr -> {
-                        Version version = Version.fromString(versionStr);
-                        fileRegistryMap.put(version, importFileRegistry(Joiner.on("/").join(fileRegistryNode, versionStr)));
+                    .forEach(version -> {
+                        fileRegistryMap.put(com.yahoo.config.provision.Version.fromString(version),
+                                            importFileRegistry(Joiner.on("/").join(fileRegistryNode, version)));
                     });
         }
     }
@@ -147,16 +175,16 @@ public class ZKApplicationPackage implements ApplicationPackage {
         return ret;
     }
 
-    public Map<Version, ProvisionInfo> getProvisionInfoMap() {
-        return Collections.unmodifiableMap(provisionInfoMap);
+    public Optional<ProvisionInfo> getProvisionInfo() {
+        return provisionInfo;
     }
 
     @Override
-    public Map<Version, FileRegistry> getFileRegistryMap() {
+    public Map<com.yahoo.config.provision.Version, FileRegistry> getFileRegistryMap() {
         return Collections.unmodifiableMap(fileRegistryMap);
     }
 
-    private Optional<PreGeneratedFileRegistry> getPreGeneratedFileRegistry(Version vespaVersion) {
+    private Optional<PreGeneratedFileRegistry> getPreGeneratedFileRegistry(com.yahoo.config.provision.Version vespaVersion) {
         // Assumes at least one file registry, which we always have.
         Optional<PreGeneratedFileRegistry> fileRegistry = Optional.ofNullable(fileRegistryMap.get(vespaVersion));
         if (!fileRegistry.isPresent()) {
@@ -243,7 +271,7 @@ public class ZKApplicationPackage implements ApplicationPackage {
     }
 
     @Override
-    public List<ComponentInfo> getComponentsInfo(Version vespaVersion) {
+    public List<ComponentInfo> getComponentsInfo(com.yahoo.config.provision.Version vespaVersion) {
         List<ComponentInfo> components = new ArrayList<>();
         PreGeneratedFileRegistry fileRegistry = getPreGeneratedFileRegistry(vespaVersion).get();
         for (String path : fileRegistry.getPaths()) {
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKLiveApp.java b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKLiveApp.java
index 88748cb7689..8084be1cefa 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKLiveApp.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKLiveApp.java
@@ -173,14 +173,11 @@ public class ZKLiveApp {
      * Returns the full list of children (file names) in the given path.
      *
      * @param path a path relative to the currently active application
-     * @return a list of file names
+     * @return a list of file names, which is empty (never null) if the path does not exist
      */
     public List<String> getChildren(String path) {
         String fullPath = getFullPath(path);
-        if (! zk.exists(fullPath)) {
-            log.fine("ZKApplicationPackage: " + fullPath + " is not a valid dir");
-            return Collections.emptyList();
-        }
+        if (! zk.exists(fullPath)) return Collections.emptyList();
         return zk.getChildren(fullPath);
     }
 
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClientTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClientTest.java
index ac029c12b17..933c1e1d64d 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClientTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClientTest.java
@@ -1,6 +1,7 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.config.server.deploy;
 
+import com.google.common.collect.ImmutableSet;
 import com.yahoo.config.application.api.ApplicationMetaData;
 import com.yahoo.config.application.api.ApplicationPackage;
 import com.yahoo.config.application.api.FileRegistry;
@@ -174,23 +175,15 @@ public class ZooKeeperClientTest extends TestWithCurator {
         Path app = Path.fromString("/1");
         ZooKeeperClient zooKeeperClient = new ZooKeeperClient(zk, logger, true, app);
         zooKeeperClient.setupZooKeeper();
-        zooKeeperClient.feedProvisionInfos(createProvisionInfos());
+        HostSpec host1 = new HostSpec("host1.yahoo.com", Collections.emptyList());
+        HostSpec host2 = new HostSpec("host2.yahoo.com", Collections.emptyList());
+        ImmutableSet<HostSpec> hosts = ImmutableSet.of(host1, host2);
+        zooKeeperClient.feedProvisionInfo(ProvisionInfo.withHosts(hosts));
         Path hostsPath = app.append(ZKApplicationPackage.allocatedHostsNode);
         assertTrue(zk.exists(hostsPath.getAbsolute()));
-        assertEquals(0, zk.getBytes(hostsPath.getAbsolute()).length); // Changed from null
-        assertTrue(zk.exists(hostsPath.append("1.2.3").getAbsolute()));
-        assertTrue(zk.exists(hostsPath.append("3.2.1").getAbsolute()));
-        assertTrue(zk.getBytes(hostsPath.append("1.2.3").getAbsolute()).length > 0);
-        assertTrue(zk.getBytes(hostsPath.append("3.2.1").getAbsolute()).length > 0);
-    }
-
-    private Map<Version, ProvisionInfo> createProvisionInfos() {
-        Map<Version, ProvisionInfo> provisionInfoMap = new HashMap<>();
-        ProvisionInfo a = ProvisionInfo.withHosts(Collections.singleton(new HostSpec("host.yahoo.com", Collections.emptyList())));
-        ProvisionInfo b = ProvisionInfo.withHosts(Collections.singleton(new HostSpec("host2.yahoo.com", Collections.emptyList())));
-        provisionInfoMap.put(Version.fromIntValues(1, 2, 3), a);
-        provisionInfoMap.put(Version.fromIntValues(3, 2, 1), b);
-        return provisionInfoMap;
+        
+        ProvisionInfo deserialized = ProvisionInfo.fromJson(zk.getBytes(hostsPath.getAbsolute()), Optional.empty());
+        assertEquals(hosts, deserialized.getHosts());
     }
 
 }
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/deploy/ZooKeeperDeployerTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/deploy/ZooKeeperDeployerTest.java
index 9c7f12c2147..b7bd7918e02 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/deploy/ZooKeeperDeployerTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/deploy/ZooKeeperDeployerTest.java
@@ -4,6 +4,7 @@ package com.yahoo.vespa.config.server.deploy;
 import com.yahoo.config.application.api.ApplicationPackage;
 import com.yahoo.config.application.api.DeployLogger;
 import com.yahoo.config.model.application.provider.*;
+import com.yahoo.config.provision.ProvisionInfo;
 import com.yahoo.config.provision.Version;
 import com.yahoo.io.IOUtils;
 import com.yahoo.path.Path;
@@ -52,7 +53,7 @@ public class ZooKeeperDeployerTest {
         ZooKeeperClient client = new ZooKeeperClient(configCurator, logger, true, appPath);
         ZooKeeperDeployer deployer = new ZooKeeperDeployer(client);
 
-        deployer.deploy(applicationPackage, Collections.singletonMap(Version.fromIntValues(1, 0, 0), new MockFileRegistry()), Collections.emptyMap());
+        deployer.deploy(applicationPackage, Collections.singletonMap(Version.fromIntValues(1, 0, 0), new MockFileRegistry()), ProvisionInfo.withHosts(Collections.emptySet()));
         assertTrue(configCurator.exists(appPath.getAbsolute()));
     }
 
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/http/v2/SessionActiveHandlerTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/http/v2/SessionActiveHandlerTest.java
index 5e10f364aeb..1719b71b071 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/http/v2/SessionActiveHandlerTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/http/v2/SessionActiveHandlerTest.java
@@ -218,7 +218,7 @@ public class SessionActiveHandlerTest extends SessionHandlerTest {
         ZooKeeperClient zkC = new ZooKeeperClient(configCurator, new BaseDeployLogger(), false, pathProvider.getSessionDirs().append(String.valueOf(sessionId)));
         VespaModelFactory modelFactory = new VespaModelFactory(new NullConfigModelRegistry());
         zkC.feedZKFileRegistries(Collections.singletonMap(modelFactory.getVersion(), new MockFileRegistry()));
-        zkC.feedProvisionInfos(Collections.singletonMap(modelFactory.getVersion(), ProvisionInfo.withHosts(Collections.emptySet())));
+        zkC.feedProvisionInfo(ProvisionInfo.withHosts(Collections.emptySet()));
         TestComponentRegistry componentRegistry = new TestComponentRegistry.Builder()
                 .curator(curator)
                 .configCurator(configCurator)
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/provision/StaticProvisionerTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/provision/StaticProvisionerTest.java
index c54514eb097..2b936a42574 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/provision/StaticProvisionerTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/provision/StaticProvisionerTest.java
@@ -20,7 +20,7 @@ import java.io.IOException;
 import static org.junit.Assert.assertEquals;
 
 /**
- * @author lulf
+ * @author Ulf Lilleengen
  */
 public class StaticProvisionerTest {
 
@@ -30,7 +30,7 @@ public class StaticProvisionerTest {
         InMemoryProvisioner inMemoryHostProvisioner = new InMemoryProvisioner(false, "host1.yahoo.com", "host2.yahoo.com", "host3.yahoo.com", "host4.yahoo.com");
         VespaModel firstModel = createModel(app, inMemoryHostProvisioner);
 
-        StaticProvisioner staticProvisioner = new StaticProvisioner(firstModel.getProvisionInfo().get());
+        StaticProvisioner staticProvisioner = new StaticProvisioner(firstModel.provisionInfo());
         VespaModel secondModel = createModel(app, staticProvisioner);
 
         assertModelConfig(firstModel, secondModel);
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/session/LocalSessionTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/session/LocalSessionTest.java
index f0086eabd26..f4be4d31943 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/session/LocalSessionTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/session/LocalSessionTest.java
@@ -160,7 +160,7 @@ public class LocalSessionTest {
         zkc.createWriteStatusTransaction(Session.Status.NEW).commit();
         ZooKeeperClient zkClient = new ZooKeeperClient(configCurator, new BaseDeployLogger(), false, appPath);
         if (provisionInfo.isPresent()) {
-            zkClient.feedProvisionInfos(Collections.singletonMap(Version.fromIntValues(0, 0, 0), provisionInfo.get()));
+            zkClient.feedProvisionInfo(provisionInfo.get());
         }
         zkClient.feedZKFileRegistries(Collections.singletonMap(Version.fromIntValues(0, 0, 0), new MockFileRegistry()));
         File sessionDir = new File(tenantFileSystemDirs.path(), String.valueOf(sessionId));
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/tenant/TenantRequestHandlerTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/tenant/TenantRequestHandlerTest.java
index 65f546e149a..3dccee1572c 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/tenant/TenantRequestHandlerTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/tenant/TenantRequestHandlerTest.java
@@ -8,6 +8,7 @@ import com.yahoo.config.model.application.provider.BaseDeployLogger;
 import com.yahoo.config.model.application.provider.FilesApplicationPackage;
 import com.yahoo.config.model.application.provider.MockFileRegistry;
 import com.yahoo.config.provision.ApplicationName;
+import com.yahoo.config.provision.ProvisionInfo;
 import com.yahoo.config.provision.Version;
 import com.yahoo.io.IOUtils;
 import com.yahoo.path.Path;
@@ -94,7 +95,7 @@ public class TenantRequestHandlerTest extends TestWithCurator {
         File app = tempFolder.newFolder();
         IOUtils.copyDirectory(appDir, app);
         ZooKeeperDeployer deployer = zkc.createDeployer(new BaseDeployLogger());
-        deployer.deploy(FilesApplicationPackage.fromFile(appDir), Collections.singletonMap(vespaVersion, new MockFileRegistry()), Collections.emptyMap());
+        deployer.deploy(FilesApplicationPackage.fromFile(appDir), Collections.singletonMap(vespaVersion, new MockFileRegistry()), ProvisionInfo.withHosts(Collections.emptySet()));
     }
 
     private ApplicationSet reloadConfig(long id, Clock clock) {
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackageTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackageTest.java
index abc77a91c51..9e91b97806d 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackageTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackageTest.java
@@ -64,8 +64,7 @@ public class ZKApplicationPackageTest extends TestWithCurator {
         assertTrue(zkApp.getFileRegistryMap().containsKey(goodVersion));
         assertFalse(zkApp.getFileRegistryMap().containsKey(Version.fromIntValues(0, 0, 0)));
         assertThat(zkApp.getFileRegistryMap().get(goodVersion).fileSourceHost(), is("dummyfiles"));
-        assertTrue(zkApp.getProvisionInfoMap().containsKey(goodVersion));
-        ProvisionInfo readInfo = zkApp.getProvisionInfoMap().get(goodVersion);
+        ProvisionInfo readInfo = zkApp.getProvisionInfo().get();
         assertThat(Utf8.toString(readInfo.toJson()), is(Utf8.toString(provisionInfo.toJson())));
         assertThat(readInfo.getHosts().iterator().next().flavor(), is(TEST_FLAVOR));
         assertTrue(zkApp.getDeployment().isPresent());
diff --git a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/provisioning/CapacityPolicies.java b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/provisioning/CapacityPolicies.java
index 914658302b6..e2ff17ba782 100644
--- a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/provisioning/CapacityPolicies.java
+++ b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/provisioning/CapacityPolicies.java
@@ -24,7 +24,6 @@ public class CapacityPolicies {
         this.flavors = flavors;
     }
 
-    /** provides capacity defaults for various environments */
     public int decideSize(Capacity requestedCapacity) {
         int requestedNodes = requestedCapacity.nodeCount();
         if (requestedCapacity.isRequired()) return requestedNodes;
@@ -39,10 +38,10 @@ public class CapacityPolicies {
     }
 
     public Flavor decideFlavor(Capacity requestedCapacity, ClusterSpec cluster, Optional<String> defaultFlavorOverride) {
-        // for now, always use requested docker flavor when requested
+        // for now, always use the requested flavor if a docker flavor is requested
         Optional<String> requestedFlavor = requestedCapacity.flavor();
         if (requestedFlavor.isPresent() &&
-                flavors.getFlavorOrThrow(requestedFlavor.get()).getType() == Flavor.Type.DOCKER_CONTAINER)
+            flavors.getFlavorOrThrow(requestedFlavor.get()).getType() == Flavor.Type.DOCKER_CONTAINER)
             return flavors.getFlavorOrThrow(requestedFlavor.get());
 
         String defaultFlavorName = defaultFlavorOverride.isPresent() ?