backend: cmd/pagination: add handlePagination func to get only limited

response size

this helps to get only limited number of resources that the users want
to access not just fetching full resource. and then set continueToken in
the proxy URL.

Author: upsaurav12

backend/cmd/headlamp.go

@@ -1322,6 +1322,7 @@ func clusterRequestHandler(c *HeadlampConfig) http.Handler { //nolint:funlen
 		if err == nil && token != "" {
 			r.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
 		}
+		handlePagination(r)
 
 		// Process WebSocket protocol headers if present
 		processWebSocketProtocolHeader(r)

backend/cmd/pagination.go

@@ -0,0 +1,20 @@
+package main
+
+import "net/http"
+
+var limit string = "20"
+
+// This sets limit and continueToken into the r.URL parameter
+// it helps to set limit and "continue" while proxying to the clusterAPI.
+func handlePagination(r *http.Request) {
+	q := r.URL.Query()
+
+	q.Set("limit", limit)
+
+	continueToken := q.Get("continueToken")
+	if continueToken != "" {
+		q.Set("continue", continueToken)
+	}
+
+	r.URL.RawQuery = q.Encode()
+}