From 25274b26d92b847df5eeb7c00281b16af8488c51 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Moritz=20Wanzenb=C3=B6ck?= <moritz.wanzenboeck@linbit.com>
Date: Tue, 15 Oct 2024 15:34:01 +0200
Subject: [PATCH] lower memory usage
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

We keep track of of all Pods in the cluster, while only caring about a small
subset of them. Since we only need very basic information from the Pod, we
can lower memory usage by ensuring we only store information we actually
care about.

Signed-off-by: Moritz Wanzenböck <moritz.wanzenboeck@linbit.com>
---
 CHANGELOG.md         |  4 ++++
 pkg/agent/agent.go   |  8 ++++++++
 pkg/cleaners/pods.go | 48 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+)
 create mode 100644 pkg/cleaners/pods.go

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a3dd758..9123103 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Filter Pod objects before storing in cache. This lowers memory usage of the HA Controller Pods.
+
 ## [1.2.1] - 2024-03-28
 
 ### Fixed
diff --git a/pkg/agent/agent.go b/pkg/agent/agent.go
index af54e72..cf14979 100644
--- a/pkg/agent/agent.go
+++ b/pkg/agent/agent.go
@@ -27,6 +27,7 @@ import (
 	"k8s.io/client-go/tools/events"
 	"k8s.io/klog/v2"
 
+	"github.com/piraeusdatastore/piraeus-ha-controller/pkg/cleaners"
 	"github.com/piraeusdatastore/piraeus-ha-controller/pkg/indexers"
 	"github.com/piraeusdatastore/piraeus-ha-controller/pkg/metadata"
 )
@@ -135,7 +136,14 @@ func NewAgent(opt *Options) (*agent, error) {
 
 	klog.V(2).Info("setting up Pod informer")
 
+	requirements, _ := opt.SatellitePodSelector.Requirements()
 	podInformer := informerFactory.Core().V1().Pods().Informer()
+	err = podInformer.SetTransform(func(o any) (any, error) {
+		return cleaners.CleanPod(o.(*corev1.Pod), requirements), nil
+	})
+	if err != nil {
+		return nil, err
+	}
 
 	err = podInformer.AddIndexers(map[string]cache.IndexFunc{
 		PodByPersistentVolumeClaimIndex: indexers.Gen(func(obj *corev1.Pod) ([]string, error) {
diff --git a/pkg/cleaners/pods.go b/pkg/cleaners/pods.go
new file mode 100644
index 0000000..ab9c97b
--- /dev/null
+++ b/pkg/cleaners/pods.go
@@ -0,0 +1,48 @@
+package cleaners
+
+import (
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
+
+	"github.com/piraeusdatastore/piraeus-ha-controller/pkg/metadata"
+)
+
+func CleanPod(pod *corev1.Pod, labelRequirements labels.Requirements) *corev1.Pod {
+	neededLabels := map[string]string{}
+	for i := range labelRequirements {
+		k := labelRequirements[i].Key()
+		if v, ok := pod.Labels[k]; ok {
+			neededLabels[k] = v
+		}
+	}
+
+	neededAnnotations := map[string]string{}
+	if v, ok := pod.Annotations[metadata.AnnotationIgnoreFailOver]; ok {
+		neededAnnotations[metadata.AnnotationIgnoreFailOver] = v
+	}
+
+	return &corev1.Pod{
+		TypeMeta: pod.TypeMeta,
+		ObjectMeta: metav1.ObjectMeta{
+			Name:              pod.Name,
+			Namespace:         pod.Namespace,
+			UID:               pod.UID,
+			ResourceVersion:   pod.ResourceVersion,
+			Labels:            neededLabels,
+			Annotations:       neededAnnotations,
+			OwnerReferences:   pod.OwnerReferences,
+			DeletionTimestamp: pod.DeletionTimestamp,
+		},
+		Spec: corev1.PodSpec{
+			// Used in "agent", "failover", "force io error pods" and "suspeded pod termination".
+			NodeName: pod.Spec.NodeName,
+			// Used in "agent" and "failover".
+			Volumes: pod.Spec.Volumes,
+		},
+		Status: corev1.PodStatus{
+			// Used in "failover" and "suspended pod termination".
+			Phase: pod.Status.Phase,
+		},
+	}
+}