Add cluster feed block support to cluster controller

Will push out a new cluster state bundle indicating cluster feed blocked
if one or more nodes in the cluster has one or more resources exhausted.
Similarly, a new state will be pushed out once no nodes have resources
exhausted any more.

The feed block description currently contains up to 3 separate exhausted
resources, possibly across multiple nodes.

A cluster-level event is emitted for both the block and unblock edges.

No hysteresis is present yet, so if a node is oscillating around a block-limit,
so will the cluster state.

1 files changed, 10 insertions, 0 deletions

diff --git a/protocols/getnodestate/host_info.json b/protocols/getnodestate/host_info.json
index b14eaa0e13c..7ae5b0043ff 100644
--- a/protocols/getnodestate/host_info.json
+++ b/protocols/getnodestate/host_info.json
@@ -103,5 +103,15 @@
                 ]
             }
         ]
+    },
+    "content-node": {
+        "resource-usage": {
+            "memory": {
+                "usage": 0.85
+            },
+            "disk": {
+                "usage": 0.6
+            }
+        }
     }
 }