From 5b7b6dae97ce963d7c4b02646a64092797384010 Mon Sep 17 00:00:00 2001
From: TwiN <twin@linux.com>
Date: Tue, 4 Oct 2022 20:13:54 -0400
Subject: [PATCH] feat: Implement paging on list operations

---
 main.go | 65 ++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 39 insertions(+), 26 deletions(-)

diff --git a/main.go b/main.go
index 6c839f1..aca6de2 100644
--- a/main.go
+++ b/main.go
@@ -11,6 +11,7 @@ import (
 
 	"github.com/xhit/go-str2duration/v2"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/client-go/dynamic"
 	"k8s.io/client-go/kubernetes"
@@ -23,6 +24,8 @@ const (
 	ExecutionTimeout                  = 20 * time.Minute      // Maximum time for each reconciliation before timing out
 	ExecutionInterval                 = 5 * time.Minute       // Interval between each reconciliation
 	ThrottleDuration                  = 50 * time.Millisecond // Duration to sleep for throttling purposes
+
+	ListLimit = 500 // Maximum number of items to list at once
 )
 
 var (
@@ -109,39 +112,49 @@ func DoReconcile(dynamicClient dynamic.Interface, resources []*metav1.APIResourc
 			}
 			// List all items under the resource
 			gvr.Resource = apiResource.Name
-			list, err := dynamicClient.Resource(gvr).List(context.TODO(), metav1.ListOptions{TimeoutSeconds: &listTimeoutSeconds})
-			if err != nil {
-				log.Printf("Error checking %s from %s: %s", gvr.Resource, gvr.GroupVersion(), err)
-				continue
-			}
-			if debug {
-				log.Println("Checking", len(list.Items), gvr.Resource, "from", gvr.GroupVersion())
-			}
-			for _, item := range list.Items {
-				ttl, exists := item.GetAnnotations()[AnnotationTTL]
-				if !exists {
-					continue
-				}
-				ttlInDuration, err := str2duration.ParseDuration(ttl)
+			var list *unstructured.UnstructuredList
+			var continueToken string
+			var err error
+			for list == nil || continueToken != "" {
+				list, err = dynamicClient.Resource(gvr).List(context.TODO(), metav1.ListOptions{TimeoutSeconds: &listTimeoutSeconds, Continue: continueToken, Limit: ListLimit})
 				if err != nil {
-					log.Printf("[%s/%s] has an invalid TTL '%s': %s\n", apiResource.Name, item.GetName(), ttl, err)
+					log.Printf("Error checking %s from %s: %s", gvr.Resource, gvr.GroupVersion(), err)
 					continue
 				}
-				ttlExpired := time.Now().After(item.GetCreationTimestamp().Add(ttlInDuration))
-				if ttlExpired {
-					log.Printf("[%s/%s] is configured with a TTL of %s, which means it has expired %s ago", apiResource.Name, item.GetName(), ttl, time.Since(item.GetCreationTimestamp().Add(ttlInDuration)).Round(time.Second))
-					err := dynamicClient.Resource(gvr).Namespace(item.GetNamespace()).Delete(context.TODO(), item.GetName(), metav1.DeleteOptions{})
+				if list != nil {
+					continueToken = list.GetContinue()
+				}
+				if debug {
+					log.Println("Checking", len(list.Items), gvr.Resource, "from", gvr.GroupVersion())
+				}
+				for _, item := range list.Items {
+					ttl, exists := item.GetAnnotations()[AnnotationTTL]
+					if !exists {
+						continue
+					}
+					ttlInDuration, err := str2duration.ParseDuration(ttl)
 					if err != nil {
-						log.Printf("[%s/%s] failed to delete: %s\n", apiResource.Name, item.GetName(), err)
-						// XXX: Should we retry with GracePeriodSeconds set to &0 to force immediate deletion after the first attempt failed?
+						log.Printf("[%s/%s] has an invalid TTL '%s': %s\n", apiResource.Name, item.GetName(), ttl, err)
+						continue
+					}
+					ttlExpired := time.Now().After(item.GetCreationTimestamp().Add(ttlInDuration))
+					if ttlExpired {
+						log.Printf("[%s/%s] is configured with a TTL of %s, which means it has expired %s ago", apiResource.Name, item.GetName(), ttl, time.Since(item.GetCreationTimestamp().Add(ttlInDuration)).Round(time.Second))
+						err := dynamicClient.Resource(gvr).Namespace(item.GetNamespace()).Delete(context.TODO(), item.GetName(), metav1.DeleteOptions{})
+						if err != nil {
+							log.Printf("[%s/%s] failed to delete: %s\n", apiResource.Name, item.GetName(), err)
+							// XXX: Should we retry with GracePeriodSeconds set to &0 to force immediate deletion after the first attempt failed?
+						} else {
+							log.Printf("[%s/%s] deleted", apiResource.Name, item.GetName())
+						}
+						// Cool off a tiny bit to avoid hitting the API too often
+						time.Sleep(ThrottleDuration)
 					} else {
-						log.Printf("[%s/%s] deleted", apiResource.Name, item.GetName())
+						log.Printf("[%s/%s] is configured with a TTL of %s, which means it will expire in %s", apiResource.Name, item.GetName(), ttl, time.Until(item.GetCreationTimestamp().Add(ttlInDuration)).Round(time.Second))
 					}
-					// Cool off a tiny bit to avoid hitting the API too often
-					time.Sleep(ThrottleDuration)
-				} else {
-					log.Printf("[%s/%s] is configured with a TTL of %s, which means it will expire in %s", apiResource.Name, item.GetName(), ttl, time.Until(item.GetCreationTimestamp().Add(ttlInDuration)).Round(time.Second))
 				}
+				// Cool off a tiny bit to avoid hitting the API too often
+				time.Sleep(ThrottleDuration)
 			}
 			// Cool off a tiny bit to avoid hitting the API too often
 			time.Sleep(ThrottleDuration)