8 files changed, 83 insertions, 66 deletions
diff --git a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneFilter.java b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneFilter.java
new file mode 100644
index 00000000000..f718b86ca40
--- /dev/null
+++ b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneFilter.java
@@ -0,0 +1,22 @@
+package com.yahoo.vespa.hosted.controller.api.integration.zone;
+
+/**
+ * A ZoneId list which can be filtered in various ways; elements can be accessed after at least one filter.
+ *
+ * The methods here return instances of {@link ZoneList}, which extends ZoneFilter, but with accessors and additional filters.
+ * This forces the developer to consider which of the filters in this class to apply, prior to processing any zones.
+ *
+ * @author jvenstad
+ */
+public interface ZoneFilter {
+
+    /** Negates the next filter. */
+    ZoneFilter not();
+
+    /** All zones from the initial pool. */
+    ZoneList all();
+
+    /** Zones where which are managed by the controller. */
+    ZoneList controllerManaged();
+
+}
diff --git a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZonesMock.java b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneFilterMock.java
index a63dadf6a46..e68bf0ccc24 100644
--- a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZonesMock.java
+++ b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneFilterMock.java
@@ -4,8 +4,10 @@ import com.yahoo.config.provision.Environment;
 import com.yahoo.config.provision.RegionName;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -14,52 +16,57 @@ import java.util.stream.Collectors;
  *
  * @author jvenstad
  */
-public class ZonesMock implements Zones.List {
+public class ZoneFilterMock implements ZoneList {
 
     private final java.util.List<ZoneId> zones;
     private final boolean negate;
 
-    private ZonesMock(java.util.List<ZoneId> zones, boolean negate) {
+    private ZoneFilterMock(java.util.List<ZoneId> zones, boolean negate) {
         this.negate = negate;
         this.zones = zones;
     }
 
-    public static Zones from(Collection<ZoneId> zones) {
-        return new ZonesMock(new ArrayList<>(zones), false);
+    public static ZoneFilter from(Collection<ZoneId> zones) {
+        return new ZoneFilterMock(new ArrayList<>(zones), false);
     }
 
     @Override
-    public Zones.List not() {
-        return new ZonesMock(zones, ! negate);
+    public ZoneList not() {
+        return new ZoneFilterMock(zones, ! negate);
     }
 
     @Override
-    public Zones.List all() {
+    public ZoneList all() {
         return filter(zoneId -> true);
     }
 
     @Override
-    public Zones.List controllerManaged() {
+    public ZoneList controllerManaged() {
         return all();
     }
 
     @Override
-    public Zones.List in(Environment environment) {
+    public ZoneList in(Environment environment) {
         return filter(zoneId -> zoneId.environment() == environment);
     }
 
     @Override
-    public Zones.List in(RegionName region) {
+    public ZoneList in(RegionName region) {
         return filter(zoneId -> zoneId.region().equals(region));
     }
 
     @Override
+    public ZoneList zones(ZoneId... zones) {
+        return filter(zoneId -> new HashSet<>(Arrays.asList(zones)).contains(zoneId));
+    }
+
+    @Override
     public java.util.List<ZoneId> ids() {
         return Collections.unmodifiableList(zones);
     }
 
-    private ZonesMock filter(Predicate<ZoneId> condition) {
-        return new ZonesMock(zones.stream().filter(negate ? condition.negate() : condition).collect(Collectors.toList()), false);
+    private ZoneFilterMock filter(Predicate<ZoneId> condition) {
+        return new ZoneFilterMock(zones.stream().filter(negate ? condition.negate() : condition).collect(Collectors.toList()), false);
     }
 
 }
diff --git a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneId.java b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneId.java
index 818f57ec44d..21ac7a654b8 100644
--- a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneId.java
+++ b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneId.java
@@ -14,7 +14,7 @@ import java.util.Objects;
  * @author jvenstad
  */
 public class ZoneId {
-    // TODO: Replace usages of zone + region with usages of this.
+    // TODO: Replace usages of environment + region with usages of this.
 
     private final Environment environment;
     private final RegionName region;
diff --git a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneList.java b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneList.java
new file mode 100644
index 00000000000..cd263769864
--- /dev/null
+++ b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneList.java
@@ -0,0 +1,34 @@
+package com.yahoo.vespa.hosted.controller.api.integration.zone;
+
+import com.yahoo.config.provision.Environment;
+import com.yahoo.config.provision.RegionName;
+
+import java.util.List;
+
+/**
+ * Provides filters for and access to a list of ZoneIds.
+ *
+ * This is typically offered after an initial filter from {@link ZoneFilter} has been applied.
+ * This forces the developer to consider which zones to process.
+ *
+ * @author jvenstad
+ */
+public interface ZoneList extends ZoneFilter {
+
+    /** Negates the next filter. */
+    @Override
+    ZoneList not();
+
+    /** Zones in the given environment. */
+    ZoneList in(Environment environment);
+
+    /** Zones in the given region. */
+    ZoneList in(RegionName region);
+
+    /** Only the given zones — combine with not() for best effect! */
+    ZoneList zones(ZoneId... zones);
+
+    /** Returns the id of all zones in this list as — you guessed it — a list. */
+    List<ZoneId> ids();
+
+}
diff --git a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneRegistry.java b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneRegistry.java
index b7eb3adadcf..03207d86983 100644
--- a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneRegistry.java
+++ b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/ZoneRegistry.java
@@ -22,7 +22,7 @@ public interface ZoneRegistry {
     boolean hasZone(ZoneId zoneId);
 
     /** Returns a list containing the id of all zones in this registry. */
-    Zones zones();
+    ZoneFilter zones();
 
     /** Returns the default region for the given environment, if one is configured. */
     Optional<RegionName> getDefaultRegion(Environment environment);
diff --git a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/Zones.java b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/Zones.java
deleted file mode 100644
index 966cb376154..00000000000
--- a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/zone/Zones.java
+++ /dev/null
@@ -1,46 +0,0 @@
-package com.yahoo.vespa.hosted.controller.api.integration.zone;
-
-import com.yahoo.config.provision.Environment;
-import com.yahoo.config.provision.RegionName;
-
-/**
- * A ZoneId list which can be filtered in various ways; elements can be accessed after at least one filter.
- *
- * The class is split in an outer and an inner class to force the user to make an initial choice between
- * the filters available in the outer class; these should be pertinent to what code should use the zone,
- * while the filters in the inner class are optional and / or for convenience.
- *
- *
- * @author jvenstad
- */
-public interface Zones {
-
-    /** Negates the next filter. */
-    Zones not();
-
-    /** All zones from the initial pool. */
-    Zones.List all();
-
-    /** Zones where which are managed by the controller. */
-    Zones.List controllerManaged();
-
-
-    /** Wraps access to the zones; this forces the user to consider which zones to access. */
-    interface List extends Zones {
-
-        /** Negates the next filter. */
-        @Override
-        Zones.List not();
-
-        /** Zones in the given environment. */
-        Zones.List in(Environment environment);
-
-        /** Zones in the given region. */
-        Zones.List in(RegionName region);
-
-        /** Returns the id of all zones in this list as — you guessed it — a list. */
-        java.util.List<ZoneId> ids();
-
-    }
-
-}
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/proxy/ConfigServerRestExecutorImpl.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/proxy/ConfigServerRestExecutorImpl.java
index 751fe25b897..e8689a06162 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/proxy/ConfigServerRestExecutorImpl.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/proxy/ConfigServerRestExecutorImpl.java
@@ -7,8 +7,8 @@ import com.yahoo.config.provision.Environment;
 import com.yahoo.vespa.hosted.controller.api.integration.zone.ZoneId;
 import com.yahoo.io.IOUtils;
 import com.yahoo.jdisc.http.HttpRequest.Method;
+import com.yahoo.vespa.hosted.controller.api.integration.zone.ZoneList;
 import com.yahoo.vespa.hosted.controller.api.integration.zone.ZoneRegistry;
-import com.yahoo.vespa.hosted.controller.api.integration.zone.Zones;
 import org.apache.http.Header;
 import org.apache.http.client.config.RequestConfig;
 import org.apache.http.client.methods.CloseableHttpResponse;
@@ -83,7 +83,7 @@ public class ConfigServerRestExecutorImpl implements ConfigServerRestExecutor {
         DiscoveryResponseStructure responseStructure = new DiscoveryResponseStructure();
         String environmentName = proxyRequest.getEnvironment();
 
-        Zones.List zones = zoneRegistry.zones().all();
+        ZoneList zones = zoneRegistry.zones().all();
         if ( ! environmentName.isEmpty())
             zones = zones.in(Environment.from(environmentName));
 
diff --git a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/ZoneRegistryMock.java b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/ZoneRegistryMock.java
index 092e21fec14..82434b6260c 100644
--- a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/ZoneRegistryMock.java
+++ b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/ZoneRegistryMock.java
@@ -9,8 +9,8 @@ import com.yahoo.config.provision.SystemName;
 import com.yahoo.vespa.hosted.controller.api.integration.zone.ZoneId;
 import com.yahoo.vespa.hosted.controller.api.identifiers.DeploymentId;
 import com.yahoo.vespa.hosted.controller.api.integration.zone.ZoneRegistry;
-import com.yahoo.vespa.hosted.controller.api.integration.zone.Zones;
-import com.yahoo.vespa.hosted.controller.api.integration.zone.ZonesMock;
+import com.yahoo.vespa.hosted.controller.api.integration.zone.ZoneFilter;
+import com.yahoo.vespa.hosted.controller.api.integration.zone.ZoneFilterMock;
 
 import java.net.URI;
 import java.time.Duration;
@@ -64,8 +64,8 @@ public class ZoneRegistryMock extends AbstractComponent implements ZoneRegistry
     }
 
     @Override
-    public Zones zones() {
-        return ZonesMock.from(Collections.unmodifiableList(zones));
+    public ZoneFilter zones() {
+        return ZoneFilterMock.from(Collections.unmodifiableList(zones));
     }
 
     @Override