Use bucket_space metric in retirement

This makes the Cluster Controller use the
vds.datastored.bucket_space.buckets_total, dimension bucketSpace=default, to
determine whether a content node manages zero buckets, and if so, will allow
the node to go permanently down. This is used when a node is retiring, and it
is to be removed from the application.

The change is guarded by the use-bucket-space-metric, default true. If the new
metric doesn't work as expected, we can revert to using the current/old metric
by flipping the flag. The flag can be controlled per application.

1 files changed, 1 insertions, 0 deletions

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 a53b0931cc6..323aa473580 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
@@ -57,6 +57,7 @@ public interface ModelContext {
         // TODO: Remove temporary default implementation
         default Optional<TlsSecrets> tlsSecrets() { return Optional.empty(); }
         double defaultTermwiseLimit();
+        boolean useBucketSpaceMetric();
     }
 
 }