Support lower bound on number of shared hosts

Adds a 'minCount' field to the shared host jackson flag, denoting the minimum
number of "shared hosts" that must exist, otherwise the deficit will be
provisioned by DynamicProvisioningMaintainer.

A "shared host" is one that is considered for allocation if current tenant node
allocations were removed: It must be a tenant host, cannot be an exclusiveTo
host, etc.

minCount requires the setting of (at least one) shared host.

2 files changed, 27 insertions, 1 deletions

diff --git a/flags/src/test/java/com/yahoo/vespa/flags/FlagsTest.java b/flags/src/test/java/com/yahoo/vespa/flags/FlagsTest.java
index 636eea2c33c..6b043ea5a89 100644
--- a/flags/src/test/java/com/yahoo/vespa/flags/FlagsTest.java
+++ b/flags/src/test/java/com/yahoo/vespa/flags/FlagsTest.java
@@ -114,7 +114,8 @@ public class FlagsTest {
         SharedHost sharedHost = new SharedHost(List.of(new HostResources(
                 4.0, 16.0, 50.0, 0.3,
                 "fast", "local",
-                10)));
+                10)),
+                null);
         testGeneric(Flags.SHARED_HOST, sharedHost);
     }
 
diff --git a/flags/src/test/java/com/yahoo/vespa/flags/custom/SharedHostTest.java b/flags/src/test/java/com/yahoo/vespa/flags/custom/SharedHostTest.java
new file mode 100644
index 00000000000..f0a11f244a4
--- /dev/null
+++ b/flags/src/test/java/com/yahoo/vespa/flags/custom/SharedHostTest.java
@@ -0,0 +1,25 @@
+// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.flags.custom;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+public class SharedHostTest {
+    @Test
+    public void serialization() throws IOException {
+        verifySerialization(new SharedHost(List.of(new HostResources(1.0, 2.0, 3.0, 4.0, "fast", "remote", 5)), 6));
+        verifySerialization(new SharedHost(List.of(new HostResources(1.0, 2.0, 3.0, 4.0, "fast", "remote", 5)), null));
+    }
+
+    private void verifySerialization(SharedHost sharedHost) throws IOException {
+        ObjectMapper mapper = new ObjectMapper();
+        String json = mapper.writeValueAsString(sharedHost);
+        SharedHost deserialized = mapper.readValue(json, SharedHost.class);
+        assertEquals(sharedHost, deserialized);
+    }
+}
\ No newline at end of file