Change nfd-master deployment mechanism from daemonset to deployment

Signed-off-by: Renaud Gaubert <rgaubert@nvidia.com>

README.md

@@ -460,8 +460,17 @@ If you want to use the latest development version (master branch) you need to
 
 #### nfd-master
 
-Nfd-master runs as a DaemonSet, by default in the master node(s)
-only. You can use the template spec provided to deploy nfd-master, or
+Nfd-master runs as a deployment (with a replica count of 1), by default
+it prefers running on the cluster's master nodes but will run on worker
+nodes if no master nodes are found.
+
+For High Availability, you should simply increase the replica count of
+the deployment object. You should also look into adding [inter-pod](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity)
+affinity to prevent masters from running on the same node.
+However note that inter-pod affinity is costly and is not recommended
+in bigger clusters.
+
+You can use the template spec provided to deploy nfd-master, or
 use `nfd-master.yaml` generated by `Makefile`. The latter includes
 `image:` and `namespace:` definitions that match the latest built
 image. Example:

nfd-master.yaml.template

@@ -37,13 +37,14 @@ subjects:
   namespace: node-feature-discovery
 ---
 apiVersion: apps/v1
-kind: DaemonSet
+kind: Deployment
 metadata:
   labels:
     app: nfd-master
   name: nfd-master
   namespace: node-feature-discovery
 spec:
+  replicas: 1
   selector:
     matchLabels:
       app: nfd-master
@@ -53,8 +54,15 @@ spec:
         app: nfd-master
     spec:
       serviceAccount: nfd-master
-      nodeSelector:
-        node-role.kubernetes.io/master: ""
+      affinity:
+        nodeAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+            - weight: 1
+              preference:
+                matchExpressions:
+                  - key: "node-role.kubernetes.io/master"
+                    operator: In
+                    values: [""]
       tolerations:
         - key: "node-role.kubernetes.io/master"
           operator: "Equal"