Require 3 config server (and controller) hosts

We already require 3 config server (and controller) nodes, but it is not
sufficient to protect the hosts from being left with only 1 healthy host: Say
the config server host application contains 2 nodes.  An upgrade of host-admin
on one of those nodes is allowed, since only the host is suspended and none of
the 2 nodes are down.  This is fixed by handling config server hosts similar to
config servers: assume 3 nodes.

1 files changed, 14 insertions, 0 deletions

diff --git a/application-model/src/main/java/com/yahoo/vespa/applicationmodel/ServiceCluster.java b/application-model/src/main/java/com/yahoo/vespa/applicationmodel/ServiceCluster.java
index 43f161cfec9..417b5792586 100644
--- a/application-model/src/main/java/com/yahoo/vespa/applicationmodel/ServiceCluster.java
+++ b/application-model/src/main/java/com/yahoo/vespa/applicationmodel/ServiceCluster.java
@@ -81,12 +81,26 @@ public class ServiceCluster {
                 Objects.equals(serviceType, ServiceType.HOST_ADMIN);
     }
 
+    public boolean isConfigServerHostLike() {
+        return isConfigServerHost() || isControllerHost();
+    }
+
     public boolean isTenantHost() {
         return isHostedVespaApplicationWithPredicate(ApplicationInstanceId::isTenantHost) &&
                 Objects.equals(clusterId, ClusterId.TENANT_HOST) &&
                 Objects.equals(serviceType, ServiceType.HOST_ADMIN);
     }
 
+    public String nodeDescription(boolean plural) {
+        String pluralSuffix = plural ? "s" : "";
+        return isConfigServer() ? "config server" + pluralSuffix :
+               isConfigServerHost() ? "config server host" + pluralSuffix :
+               isController() ? "controller" + pluralSuffix :
+               isControllerHost() ? "controller host" + pluralSuffix :
+               isTenantHost() ? "tenant host" + pluralSuffix :
+               "node" + pluralSuffix + " of {" + serviceType + "," + clusterId + "}";
+    }
+
     private boolean isHostedVespaApplicationWithId(ApplicationInstanceId id) {
         return isHostedVespaTenant() &&
                applicationInstance.map(app -> Objects.equals(app.applicationInstanceId(), id)).orElse(false);