From ed1c74d1877ff7c2724e5843b2a4038ed578ac13 Mon Sep 17 00:00:00 2001
From: Malay Kumar Parida <mparida@redhat.com>
Date: Mon, 2 Dec 2024 14:25:41 +0530
Subject: [PATCH] Add default TSCs if not present to ensure even distribution
 of OSDs

When parts of the placement spec, such as tolerations or node affinity,
are defined, the ocs-operator stops applying default placement specs,
including TSCs. The osd distribution may become potentially uneven in
absence of the TSC. Always adding default TSCs ensures consistent and
balanced OSD placement across nodes.

Signed-off-by: Malay Kumar Parida <mparida@redhat.com>
---
 controllers/storagecluster/cephcluster.go | 74 ++++++++++++-----------
 1 file changed, 40 insertions(+), 34 deletions(-)

diff --git a/controllers/storagecluster/cephcluster.go b/controllers/storagecluster/cephcluster.go
index 96304a05e0..1cfaad2717 100644
--- a/controllers/storagecluster/cephcluster.go
+++ b/controllers/storagecluster/cephcluster.go
@@ -783,21 +783,21 @@ func newStorageClassDeviceSets(sc *ocsv1.StorageCluster) []rookCephv1.StorageCla
 		topologyKey := ds.TopologyKey
 		topologyKeyValues := []string{}
 
-		noPlacement := ds.Placement.NodeAffinity == nil && ds.Placement.PodAffinity == nil && ds.Placement.PodAntiAffinity == nil && ds.Placement.TopologySpreadConstraints == nil
-		noPreparePlacement := ds.PreparePlacement.NodeAffinity == nil && ds.PreparePlacement.PodAffinity == nil && ds.PreparePlacement.PodAntiAffinity == nil && ds.PreparePlacement.TopologySpreadConstraints == nil
+		noPlacementTsc := ds.Placement.TopologySpreadConstraints == nil
+		noPlacement := ds.Placement.NodeAffinity == nil && ds.Placement.PodAffinity == nil && ds.Placement.PodAntiAffinity == nil && noPlacementTsc
+		noPreparePlacementTsc := ds.PreparePlacement.TopologySpreadConstraints == nil
+		noPreparePlacement := ds.PreparePlacement.NodeAffinity == nil && ds.PreparePlacement.PodAffinity == nil && ds.PreparePlacement.PodAntiAffinity == nil && noPreparePlacementTsc
 
-		if noPlacement {
-			if topologyKey == "" {
-				topologyKey = getFailureDomain(sc)
-			}
+		if topologyKey == "" {
+			topologyKey = getFailureDomain(sc)
+		}
 
-			if topologyKey == "host" {
-				portable = false
-			}
+		if topologyKey == "host" {
+			portable = false
+		}
 
-			if topologyMap != nil {
-				topologyKey, topologyKeyValues = topologyMap.GetKeyValues(topologyKey)
-			}
+		if topologyMap != nil {
+			topologyKey, topologyKeyValues = topologyMap.GetKeyValues(topologyKey)
 		}
 
 		count, replica := countAndReplicaOf(&ds)
@@ -812,28 +812,7 @@ func newStorageClassDeviceSets(sc *ocsv1.StorageCluster) []rookCephv1.StorageCla
 				if noPreparePlacement {
 					in := getPlacement(sc, "osd-prepare")
 					(&in).DeepCopyInto(&preparePlacement)
-				}
-
-				if len(topologyKeyValues) >= getMinDeviceSetReplica(sc) {
-					// Hard constraints are set in OSD placement for portable volumes with rack failure domain
-					// domain as there is no node affinity in PVs. This restricts the movement of OSDs
-					// between failure domain.
-					if portable && !strings.Contains(topologyKey, "zone") {
-						addStrictFailureDomainTSC(&placement, topologyKey)
-					}
-					// If topologyKey is not host, append additional topology spread constraint to the
-					// default preparePlacement. This serves even distribution at the host level
-					// within a failure domain (zone/rack).
-					if noPreparePlacement {
-						if topologyKey != corev1.LabelHostname {
-							addStrictFailureDomainTSC(&preparePlacement, topologyKey)
-						} else {
-							preparePlacement.TopologySpreadConstraints[0].TopologyKey = topologyKey
-						}
-					}
-				}
-
-				if !noPreparePlacement {
+				} else {
 					preparePlacement = ds.PreparePlacement
 				}
 			} else if !noPlacement && noPreparePlacement {
@@ -844,6 +823,33 @@ func newStorageClassDeviceSets(sc *ocsv1.StorageCluster) []rookCephv1.StorageCla
 				placement = ds.Placement
 			}
 
+			// Add default TSCs if not set to ensure even distribution of OSDs across nodes
+			if len(placement.TopologySpreadConstraints) == 0 {
+				placement.TopologySpreadConstraints = append(placement.TopologySpreadConstraints, defaults.DaemonPlacements["osd"].TopologySpreadConstraints...)
+			}
+			if len(preparePlacement.TopologySpreadConstraints) == 0 {
+				preparePlacement.TopologySpreadConstraints = append(preparePlacement.TopologySpreadConstraints, defaults.DaemonPlacements["osd-prepare"].TopologySpreadConstraints...)
+			}
+
+			if len(topologyKeyValues) >= getMinDeviceSetReplica(sc) {
+				// Hard constraints are set in OSD placement for portable volumes with rack failure domain
+				// domain as there is no node affinity in PVs. This restricts the movement of OSDs
+				// between failure domain.
+				if noPlacementTsc && portable && !strings.Contains(topologyKey, "zone") {
+					addStrictFailureDomainTSC(&placement, topologyKey)
+				}
+				// If topologyKey is not host, append additional topology spread constraint to the
+				// default preparePlacement. This serves even distribution at the host level
+				// within a failure domain (zone/rack).
+				if noPlacementTsc && noPreparePlacementTsc {
+					if topologyKey != corev1.LabelHostname {
+						addStrictFailureDomainTSC(&preparePlacement, topologyKey)
+					} else {
+						preparePlacement.TopologySpreadConstraints[0].TopologyKey = topologyKey
+					}
+				}
+			}
+
 			// Annotation crushDeviceClass ensures osd with different CRUSH device class than the one detected by Ceph
 			crushDeviceClass := ds.DeviceType
 			if ds.DeviceClass != "" {