Accurate event recording by support export

This update corrects the current behavior of the support export
command's event capture, adds relevant Kuttl checks and documents
Kubernetes Event storage duration.

Issue: [sc-17993]

Author: tjmoore4

docs/content/reference/pgo_support_export.md

@@ -34,6 +34,12 @@ PostgresCluster.
 
     Note: This RBAC needs to be cluster-scoped to retrieve information on nodes.
 
+#### Event Capture
+    Support export captures all Events in the PostgresCluster's Namespace.
+    Event duration is determined by the '--event-ttl' setting of the Kubernetes
+    API server. Default is 1 hour.
+    - https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/
+
 ```
 pgo support export CLUSTER_NAME [flags]
 ```

internal/cmd/export.go

@@ -134,7 +134,13 @@ PostgresCluster.
     services                                            [get list]
     statefulsets.apps                                   [get list]
 
-    Note: This RBAC needs to be cluster-scoped to retrieve information on nodes.`,
+    Note: This RBAC needs to be cluster-scoped to retrieve information on nodes.
+
+#### Event Capture
+    Support export captures all Events in the PostgresCluster's Namespace.
+    Event duration is determined by the '--event-ttl' setting of the Kubernetes
+    API server. Default is 1 hour.
+    - https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/`,
 	}
 
 	// Set output to log and write to buffer for writing to file
@@ -616,6 +622,9 @@ func gatherEvents(ctx context.Context,
 			strings.TrimSpace(event.Message),
 		)
 	}
+	if err := p.Flush(); err != nil {
+		return err
+	}
 
 	path := clusterName + "/events"
 	if err := writeTar(tw, buf.Bytes(), path, cmd); err != nil {

testing/kuttl/e2e/support-export/01--support_export.yaml

@@ -32,4 +32,22 @@ commands:
       exit 1
     fi
 
+    # check that the events file exist and is not empty
+    EVENTS="./kuttl-support-cluster/events"
+
+    if [[ ! -s $EVENTS ]]
+    then
+      echo "Expected Events file to not be empty"
+      eval "$CLEANUP"
+      exit 1
+    fi
+
+    # check that the events file contains the expected string
+    if ! grep -Fq "Created container postgres-startup" $EVENTS
+    then
+      echo "Events file does not contain expected string"
+      eval "$CLEANUP"
+      exit 1
+    fi
+
 - script: rm -r ./kuttl-support-cluster ./crunchy_k8s_support_export_*.tar