docs: Add missing RBAC requirements for calendar catch-up (#1108)

* docs: Add missing RBAC requirements for calendar catch-up

Signed-off-by: Derek Wang <[email protected]>

docs/eventsources/calendar-catch-up.md

@@ -3,32 +3,67 @@
 Catch-up feature allow Calender eventsources to execute the missed schedules
 from last run.
 
-## Enable Catch-up forEventSource Definition
+## Enable Catch-up for Calendar EventSource
 
-User can configure catchup on each events in eventsource.
+User can configure catch up on each events in eventsource.
 
 ```yaml
-example-with-catch-up:
-  # Catchup the missed events from last Event timestamp. last event will be persisted in configmap.
-  schedule: "* * * * *"
-  persistence:
-    catchup:
-      enabled: true # Check missed schedules from last persisted event time on every start
-      maxDuration: 5m # maximum amount of duration go back for the catch-up
-    configMap: # Configmap for persist the last successful event timestamp
-      createIfNotExist: true
-      name: test-configmap
+apiVersion: argoproj.io/v1alpha1
+kind: EventSource
+metadata:
+  name: calendar
+spec:
+  template:
+    serviceAccountName: configmap-sa # assign a service account with read, write permissions on configmaps
+  calendar:
+    example-with-catch-up:
+      # Catchup the missed events from last Event timestamp. last event will be persisted in configmap.
+      schedule: "* * * * *"
+      persistence:
+        catchup:
+          enabled: true # Check missed schedules from last persisted event time on every start
+          maxDuration: 5m # maximum amount of duration go back for the catch-up
+        configMap: # Configmap for persist the last successful event timestamp
+          createIfNotExist: true
+          name: test-configmap
 ```
 
-Last calender event persisted in configured configmap. Multiple event can use
-the same configmap to persist the events.
+Last calender event persisted in configured configmap. Same configmap can be
+used by multiple events configuration.
 
 ```yaml
 data:
   calendar.example-with-catch-up:
     '{"eventTime":"2020-10-19 22:50:00.0003192 +0000 UTC m=+683.567066901"}'
 ```
 
+### Service Account
+
+To make Calendar EventSource catch-up work, a Service Account with proper RBAC
+settings needs to be provided.
+
+If the configMap is not existing, and `createIfNotExist: true` is set, a Service
+Account bound with following `Role` is required.
+
+```yaml
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: example-configmap-access-role
+rules:
+  - apiGroups:
+      - ""
+    resources:
+      - configmaps
+    verbs:
+      - get
+      - create
+      - update
+```
+
+If the configmap is already existing, `create` can be removed from the `verbs`
+list.
+
 ## Disable the catchup
 
 Set `false` to catchup-->enabled element

examples/event-sources/calendar.yaml

@@ -10,6 +10,7 @@ spec:
 
 #    example-with-catchup:
 #    # Catchup the missed events from last Event timestamp. last event will be persisted in configmap.
+#    # A service account with configmap get/create/update privileges needs to be configured
 #      schedule: "* * * * *"
 #      persistence:
 #        catchup: