Add master NodeSelector to SNMP pods

SNMP pods should not be installed on worker nodes, since
trap generation will not work as expected.

This change adds a node-role.kubernetes.io/master NodeSelector
in order to force the pods to be Scheduled only on master nodes.

Closes-Bug: 1955571

Test Plan:

PASS: Verify that tolerations and NodeSelector are installed properly.

PASS: Add a NoSchedule taint to master nodes and verify that
pods are not being scheduled on worker nodes.

Signed-off-by: Enzo Candotti <enzo.candotti@windriver.com>
Change-Id: I28c279187463cfdc79fd39f40a817be4ee4cf011

stx-snmp-helm/stx-snmp-helm/helm-charts/snmp/templates/deployment.yaml

@@ -23,10 +23,14 @@ spec:
     spec:
       imagePullSecrets:
         - name: default-registry-key
+{{- with .Values.tolerations }}
       tolerations:
-        - key: "node-role.kubernetes.io/master"
+{{ toYaml . | indent 6 }}
-          operator: "Exists"
+{{- end }}
-          effect: "NoSchedule"
+{{- if .Values.nodeSelector }}
+      nodeSelector:
+{{ .Values.nodeSelector | toYaml | trim | indent 8 }}
+{{- end }}
       containers:
         - name: {{ .Chart.Name }}
           image: "{{ .Values.snmp.image.repository }}:{{ .Values.snmp.image.tag }}"

stx-snmp-helm/stx-snmp-helm/helm-charts/snmp/values.yaml

@@ -30,6 +30,13 @@ image:
 nameOverride: ""
 fullnameOverride: ""
 
+nodeSelector: { node-role.kubernetes.io/master: "" }
+
+tolerations:
+  - key: "node-role.kubernetes.io/master"
+    operator: "Exists"
+    effect: "NoSchedule"
+
 configmap:
   name_snmpd: snmpd-etc-config
   name_fm: snmpd-fm