fix: duplicate offerings on cache miss (#7845)

pkg/providers/instancetype/offering/provider.go

@@ -165,7 +165,6 @@ func (p *DefaultProvider) createOfferings(
 					offering.Requirements.Add(scheduling.NewRequirement(v1.LabelTopologyZoneID, corev1.NodeSelectorOpIn, id))
 				}
 				cachedOfferings = append(cachedOfferings, offering)
-				offerings = append(cachedOfferings, offering)
 			}
 		}
 		p.cache.SetDefault(p.cacheKeyFromInstanceType(it), cachedOfferings)

pkg/providers/instancetype/suite_test.go

@@ -2383,6 +2383,33 @@ var _ = Describe("InstanceTypeProvider", func() {
 			})
 		})
 	})
+	Context("Offerings", func() {
+		It("should create a single offering per instance pool", func() {
+			ExpectApplied(ctx, env.Client, nodeClass)
+			// Test twice to ensure we get the same result for a cache miss and hit
+			for range 2 {
+				instanceTypes, err := cloudProvider.GetInstanceTypes(ctx, nodePool)
+				Expect(err).ToNot(HaveOccurred())
+				type instancePool struct {
+					instanceType string
+					zone         string
+					capacityType string
+				}
+				pools := sets.New[instancePool]()
+				for _, it := range instanceTypes {
+					for _, o := range it.Offerings {
+						pool := instancePool{
+							instanceType: it.Name,
+							zone:         o.Zone(),
+							capacityType: o.CapacityType(),
+						}
+						Expect(pools.Has(pool)).To(BeFalse())
+						pools.Insert(pool)
+					}
+				}
+			}
+		})
+	})
 	Context("Provider Cache", func() {
 		// Keeping the Cache testing in one IT block to validate the combinatorial expansion of instance types generated by different configs
 		It("changes to kubelet configuration fields should result in a different set of instances types", func() {