prometheus-alertmanager: Add container security context

This adds the container security context to set
readOnlyRootFilesystem to true

Change-Id: Ic8d33ae817ace49bf5ead40b2b41c6002217aa5e

prometheus-alertmanager/templates/statefulset.yaml

@@ -47,8 +47,6 @@ spec:
         configmap-etc-hash: {{ tuple "configmap-etc.yaml" . | include "helm-toolkit.utils.hash" }}
 {{ dict "envAll" $envAll "podName" "alertmanager" "containerNames" (list "alertmanager") | include "helm-toolkit.snippets.kubernetes_mandatory_access_control_annotation" | indent 8 }}
     spec:
-      securityContext:
-        readOnlyRootFilesystem: true
 {{ dict "envAll" $envAll "application" "alertmanager" | include "helm-toolkit.snippets.kubernetes_pod_security_context" | indent 6 }}
       serviceAccountName: {{ $serviceAccountName }}
       affinity:
@@ -75,8 +73,7 @@ spec:
         - name: alertmanager
 {{ tuple $envAll "alertmanager" | include "helm-toolkit.snippets.image" | indent 10 }}
 {{ tuple $envAll $envAll.Values.pod.resources.alertmanager | include "helm-toolkit.snippets.kubernetes_resources" | indent 10 }}
-          securityContext:
-            allowPrivilegeEscalation: false
+{{ dict "envAll" $envAll "application" "alertmanager" "container" "alertmanager" | include "helm-toolkit.snippets.kubernetes_container_security_context" | indent 10 }}
           command:
             - /tmp/alertmanager.sh
             - start

prometheus-alertmanager/values.yaml

@@ -42,9 +42,14 @@ pod:
     type: apparmor
     alertmanager:
       alertmanager: localhost/docker-default
-  user:
+  security_context:
     alertmanager:
-      uid: 65534
+      pod:
+        runAsUser: 65534
+      container:
+        alertmanager:
+          allowPrivilegeEscalation: false
+          readOnlyRootFilesystem: true
   affinity:
     anti:
       type: