diff --git a/Makefile b/Makefile
index b324f38c..4d052799 100644
--- a/Makefile
+++ b/Makefile
@@ -76,12 +76,12 @@ mod-tidy: ## Run go mod tidy against code.
 test: manifests generate fmt vet envtest ## Run tests.
 	@echo "Check for kubernetes version $(K8S_VERSION_TRIMMED_V) in $(ENVTEST)"
 	@$(ENVTEST) list | grep -q $(K8S_VERSION_TRIMMED_V)
-	KUBEBUILDER_ASSETS="$(shell $(ENVTEST) use $(K8S_VERSION_TRIMMED_V) --bin-dir $(LOCALBIN) -p path)" go test $$(go list ./... | grep -v /e2e) -coverprofile cover.out
+	KUBEBUILDER_ASSETS="$(shell $(ENVTEST) use $(K8S_VERSION_TRIMMED_V) --bin-dir $(LOCALBIN) -p path)" go test $$(go list ./... | grep -v /e2e) -coverprofile cover.out -v
 
 # Utilize Kind or modify the e2e tests to load the image locally, enabling compatibility with other vendors.
 .PHONY: test-e2e  # Run the e2e tests against a Kind k8s instance that is spun up.
-test-e2e:
-	go test ./test/e2e/ -v -ginkgo.v
+test-e2e: ginkgo
+	$(GINKGO) -v ./test/e2e/
 
 .PHONY: lint
 lint: golangci-lint ## Run golangci-lint linter & yamllint
@@ -203,11 +203,11 @@ kind-load: docker-build kind ## Build and upload docker image to the local Kind
 .PHONY: kind-create
 kind-create: kind yq ## Create kubernetes cluster using Kind.
 	@if ! $(KIND) get clusters | grep -q $(KIND_CLUSTER_NAME); then \
-		$(KIND) create cluster --name $(KIND_CLUSTER_NAME) --image kindest/node:$(K8S_VERSION); \
+		$(KIND) create cluster --name $(KIND_CLUSTER_NAME) --image kindest/node:$(K8S_VERSION) --config=test/e2e/testdata/kind.yaml; \
 	fi
 	@if ! $(CONTAINER_TOOL) container inspect $$($(KIND) get nodes) | $(YQ) e '.[0].Config.Image' | grep -q $(K8S_VERSION); then \
   		$(KIND) delete cluster --name $(KIND_CLUSTER_NAME); \
-		$(KIND) create cluster --name $(KIND_CLUSTER_NAME) --image kindest/node:$(K8S_VERSION); \
+		$(KIND) create cluster --name $(KIND_CLUSTER_NAME) --image kindest/node:$(K8S_VERSION)  --config=test/e2e/testdata/kind.yaml; \
 	fi
 
 .PHONY: kind-delete
@@ -249,6 +249,7 @@ HELM ?= $(LOCALBIN)/helm
 HELM_DOCS ?= $(LOCALBIN)/helm-docs
 YQ = $(LOCALBIN)/yq
 CRD_REF_DOCS ?= $(LOCALBIN)/crd-ref-docs
+GINKGO ?= $(LOCALBIN)/ginkgo
 
 ## Tool Versions
 # renovate: datasource=github-tags depName=kubernetes-sigs/kustomize
@@ -268,6 +269,8 @@ HELM_SCHEMA_VERSION ?= v1.4.1
 HELM_DOCS_VERSION ?= v1.13.1
 # renovate: datasource=github-tags depName=mikefarah/yq
 YQ_VERSION ?= v4.44.1
+# renovate: datasource=github-tags depName=onsi/ginkgo
+GINKGO_VERSION ?= v2.19.0
 
 ## Tool install scripts
 KUSTOMIZE_INSTALL_SCRIPT ?= "https://raw.githubusercontent.com/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh"
@@ -298,6 +301,11 @@ golangci-lint: $(LOCALBIN)
 	@test -x $(GOLANGCI_LINT) && $(GOLANGCI_LINT) version | grep -q $(GOLANGCI_LINT_VERSION) || \
 	GOBIN=$(LOCALBIN) go install github.com/golangci/golangci-lint/cmd/golangci-lint@$(GOLANGCI_LINT_VERSION)
 
+.PHONY: ginkgo
+ginkgo: $(LOCALBIN)
+	@test -x $(GINKGO) && $(GINKGO) version | grep -q $(GINKGO_VERSION) || \
+	GOBIN=$(LOCALBIN) go install github.com/onsi/ginkgo/v2/ginkgo@$(GINKGO_VERSION)
+
 .PHONY: nilaway
 nilaway: $(LOCALBIN)
 	@test -x $(NILAWAY_LINT) || GOBIN=$(LOCALBIN) go install go.uber.org/nilaway/cmd/nilaway@latest
diff --git a/config/manager/manager.yaml b/config/manager/manager.yaml
index d657a5e9..4d4f9b29 100644
--- a/config/manager/manager.yaml
+++ b/config/manager/manager.yaml
@@ -88,7 +88,7 @@ spec:
           httpGet:
             path: /readyz
             port: 8081
-          initialDelaySeconds: 5
+          initialDelaySeconds: 0
           periodSeconds: 10
         # TODO(user): Configure the resources accordingly based on the project requirements.
         # More info: https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/
diff --git a/go.mod b/go.mod
index d74f4195..95f6139b 100644
--- a/go.mod
+++ b/go.mod
@@ -28,6 +28,7 @@ require (
 	github.com/coreos/go-systemd/v22 v22.5.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/emicklei/go-restful/v3 v3.11.0 // indirect
+	github.com/evanphx/json-patch v5.7.0+incompatible // indirect
 	github.com/evanphx/json-patch/v5 v5.9.0 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
 	github.com/go-logr/zapr v1.3.0 // indirect
diff --git a/go.sum b/go.sum
index a13159d3..aaf91b21 100644
--- a/go.sum
+++ b/go.sum
@@ -18,8 +18,8 @@ github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkp
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/emicklei/go-restful/v3 v3.11.0 h1:rAQeMHw1c7zTmncogyy8VvRZwtkmkZ4FxERmMY4rD+g=
 github.com/emicklei/go-restful/v3 v3.11.0/go.mod h1:6n3XBCmQQb25CM2LCACGz8ukIrRry+4bhvbpWn3mrbc=
-github.com/evanphx/json-patch v4.12.0+incompatible h1:4onqiflcdA9EOZ4RxV643DvftH5pOlLGNtQ5lPWQu84=
-github.com/evanphx/json-patch v4.12.0+incompatible/go.mod h1:50XU6AFN0ol/bzJsmQLiYLvXMP4fmwYFNcr97nuDLSk=
+github.com/evanphx/json-patch v5.7.0+incompatible h1:vgGkfT/9f8zE6tvSCe74nfpAVDQ2tG6yudJd8LBksgI=
+github.com/evanphx/json-patch v5.7.0+incompatible/go.mod h1:50XU6AFN0ol/bzJsmQLiYLvXMP4fmwYFNcr97nuDLSk=
 github.com/evanphx/json-patch/v5 v5.9.0 h1:kcBlZQbplgElYIlo/n1hJbls2z/1awpXxpRi0/FOJfg=
 github.com/evanphx/json-patch/v5 v5.9.0/go.mod h1:VNkHZ/282BpEyt/tObQO8s5CMPmYYq14uClGH4abBuQ=
 github.com/frankban/quicktest v1.14.6 h1:7Xjx+VpznH+oBnejlPUj8oUpdxnVs4f8XU8WnHkI4W8=
diff --git a/test/e2e/e2e_test.go b/test/e2e/e2e_test.go
index c9967858..3d723d29 100644
--- a/test/e2e/e2e_test.go
+++ b/test/e2e/e2e_test.go
@@ -20,7 +20,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
-	"sync"
+	"time"
 
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
@@ -31,6 +31,7 @@ import (
 )
 
 var _ = Describe("etcd-operator", Ordered, func() {
+	dir, _ := utils.GetProjectDir()
 
 	BeforeAll(func() {
 		var err error
@@ -55,7 +56,7 @@ var _ = Describe("etcd-operator", Ordered, func() {
 		By("wait while etcd-operator is ready", func() {
 			cmd := exec.Command("kubectl", "wait", "--namespace",
 				"etcd-operator-system", "deployment/etcd-operator-controller-manager",
-				"--for", "jsonpath={.status.availableReplicas}=1", "--timeout=5m")
+				"--for", "jsonpath={.status.readyReplicas}=1", "--timeout=5m")
 			_, err = utils.Run(cmd)
 			ExpectWithOffset(1, err).NotTo(HaveOccurred())
 		})
@@ -73,17 +74,10 @@ var _ = Describe("etcd-operator", Ordered, func() {
 
 	Context("Simple", func() {
 		It("should deploy etcd cluster", func() {
-			var err error
 			const namespace = "test-simple-etcd-cluster"
-			var wg sync.WaitGroup
-			wg.Add(1)
 
-			By("create namespace", func() {
-				cmd := exec.Command("sh", "-c",
-					fmt.Sprintf("kubectl create namespace %s --dry-run=client -o yaml | kubectl apply -f -", namespace)) // nolint:lll
-				_, err = utils.Run(cmd)
-				ExpectWithOffset(1, err).NotTo(HaveOccurred())
-			})
+			CreateNamespace(namespace)
+			DeferCleanup(DeleteNamespaceCB(namespace))
 
 			By("apply simple etcd cluster manifest", func() {
 				dir, _ := utils.GetProjectDir()
@@ -91,30 +85,25 @@ var _ = Describe("etcd-operator", Ordered, func() {
 					"--filename", dir+"/examples/manifests/etcdcluster-simple.yaml",
 					"--namespace", namespace,
 				)
-				_, err = utils.Run(cmd)
+				_, err := utils.Run(cmd)
 				ExpectWithOffset(1, err).NotTo(HaveOccurred())
 			})
 
-			By("wait for statefulset is ready", func() {
-				cmd := exec.Command("kubectl", "wait",
-					"statefulset/test",
-					"--for", "jsonpath={.status.readyReplicas}=3",
-					"--namespace", namespace,
-					"--timeout", "5m",
-				)
-				_, err = utils.Run(cmd)
-				ExpectWithOffset(1, err).NotTo(HaveOccurred())
-			})
+			WaitSTSReady("statefulset/test", namespace)
+
+			var etcdClient *clientv3.Client
 
-			client, err := utils.GetEtcdClient(ctx, client.ObjectKey{Namespace: namespace, Name: "test"})
+			// By("get etcd client", func() {
+			etcdClient, err := utils.GetEtcdClient(ctx, client.ObjectKey{Namespace: namespace, Name: "test"})
 			Expect(err).NotTo(HaveOccurred())
 			defer func() {
-				err := client.Close()
+				err := etcdClient.Close()
 				Expect(err).NotTo(HaveOccurred())
 			}()
+			// })
 
 			By("check etcd cluster is healthy", func() {
-				Expect(utils.IsEtcdClusterHealthy(ctx, client)).To(BeTrue())
+				Expect(utils.IsEtcdClusterHealthy(ctx, etcdClient)).To(BeTrue())
 			})
 
 		})
@@ -124,8 +113,6 @@ var _ = Describe("etcd-operator", Ordered, func() {
 		It("should deploy etcd cluster with auth", func() {
 			var err error
 			const namespace = "test-tls-auth-etcd-cluster"
-			var wg sync.WaitGroup
-			wg.Add(1)
 
 			By("create namespace", func() {
 				cmd := exec.Command("sh", "-c", fmt.Sprintf("kubectl create namespace %s --dry-run=client -o yaml | kubectl apply -f -", namespace)) //nolint:lll
@@ -146,7 +133,7 @@ var _ = Describe("etcd-operator", Ordered, func() {
 			By("wait for statefulset is ready", func() {
 				cmd := exec.Command("kubectl", "wait",
 					"statefulset/test",
-					"--for", "jsonpath={.status.availableReplicas}=3",
+					"--for", "jsonpath={.status.readyReplicas}=3",
 					"--namespace", namespace,
 					"--timeout", "5m",
 				)
@@ -154,18 +141,22 @@ var _ = Describe("etcd-operator", Ordered, func() {
 				ExpectWithOffset(1, err).NotTo(HaveOccurred())
 			})
 
-			client, err := utils.GetEtcdClient(ctx, client.ObjectKey{Namespace: namespace, Name: "test"})
+			var etcdClient *clientv3.Client
+
+			// By("get etcd client", func() {
+			etcdClient, err = utils.GetEtcdClient(ctx, client.ObjectKey{Namespace: namespace, Name: "test"})
 			Expect(err).NotTo(HaveOccurred())
 			defer func() {
-				err := client.Close()
+				err := etcdClient.Close()
 				Expect(err).NotTo(HaveOccurred())
 			}()
+			// })
 
 			By("check etcd cluster is healthy", func() {
-				Expect(utils.IsEtcdClusterHealthy(ctx, client)).To(BeTrue())
+				Expect(utils.IsEtcdClusterHealthy(ctx, etcdClient)).To(BeTrue())
 			})
 
-			auth := clientv3.NewAuth(client)
+			auth := clientv3.NewAuth(etcdClient)
 
 			By("check root role is created", func() {
 				_, err = auth.RoleGet(ctx, "root")
@@ -187,4 +178,142 @@ var _ = Describe("etcd-operator", Ordered, func() {
 		})
 	})
 
+	DescribeTable("Upgrade",
+		func(namespace string, fileName string, version string) {
+			CreateNamespace(namespace)
+			DeferCleanup(DeleteNamespaceCB(namespace))
+
+			By("apply upgrade etcd cluster manifest", func() {
+				cmd := exec.Command("kubectl", "apply",
+					"--filename", dir+fileName,
+					"--namespace", namespace,
+				)
+				_, err := utils.Run(cmd)
+
+				ExpectWithOffset(1, err).NotTo(HaveOccurred())
+			})
+
+			var etcdClient *clientv3.Client
+
+			// By("get etcd client", func() {
+			etcdClient, err := utils.GetEtcdClient(ctx, client.ObjectKey{Namespace: namespace, Name: "test"})
+			Expect(err).NotTo(HaveOccurred())
+			defer func() {
+				err := etcdClient.Close()
+				Expect(err).NotTo(HaveOccurred())
+			}()
+			// })
+
+			WaitSTSReady("statefulset/test", namespace)
+
+			By("check etcd cluster is healthy", func() {
+				Expect(utils.IsEtcdClusterHealthy(ctx, etcdClient)).To(BeTrue())
+			})
+			By("upgrade etcd cluster to one patch version", func() {
+				cmd := exec.Command("kubectl", "patch",
+					"etcdcluster/test",
+					"--type", "json",
+					// Strategic Merge Patch is not currently supported by the etcd-operator
+					// "--patch",
+					// fmt.Sprintf(
+					//  "{\"spec\":{\"podTemplate\":{\"containers\":[{\"name\":\"etcd\",\"image\":\"quay.io/coreos/etcd:%s\"}]}}}",
+					//  version,
+					// ),
+					"--patch",
+					fmt.Sprintf(
+						"[{\"op\": \"replace\", \"path\": \"/spec/podTemplate/spec/containers/0/image\", "+
+							"\"value\":\"quay.io/coreos/etcd:%s\"}]",
+						version,
+					),
+					"--namespace", namespace,
+				)
+				_, err := utils.Run(cmd)
+				ExpectWithOffset(1, err).NotTo(HaveOccurred())
+			})
+
+			// Give the operator some time to update the sts
+			time.Sleep(2 * time.Second)
+
+			WaitSTSReady("statefulset/test", namespace)
+			By("check etcd cluster is healthy", func() {
+				Expect(utils.IsEtcdClusterHealthy(ctx, etcdClient)).To(BeTrue())
+			})
+		},
+		Entry(
+			"should upgrade etcd cluster patch version",
+			"test-upgrade-3-5-11--3-5-12",
+			"/test/e2e/testdata/etcdcluster-3.5.yaml",
+			"v3.5.12",
+		),
+		Entry(
+			"should downgrade etcd cluster patch version",
+			"test-downgrade-3-5-11--3-5-10",
+			"/test/e2e/testdata/etcdcluster-3.5.yaml",
+			"v3.5.10",
+		),
+		Entry(
+			"should upgrade etcd cluster to one minor version",
+			"test-upgrade-3-4-32--3-5-10",
+			"/test/e2e/testdata/etcdcluster-3.4.yaml",
+			"v3.5.10",
+		),
+		Entry(
+			"should downgrade etcd cluster to one minor version",
+			"test-downgrade-3-5-11--3-4-32",
+			"/test/e2e/testdata/etcdcluster-3.5.yaml",
+			"v3.4.32",
+		),
+		Entry(
+			"should upgrade etcd cluster to multiple minor version",
+			"test-upgrade-3-3-27--3-5-11",
+			"/test/e2e/testdata/etcdcluster-3.3.yaml",
+			"v3.5.11",
+		),
+		Entry(
+			"should downgrade etcd cluster to multiple minor version",
+			"test-downgrade-3-5-11--3-3-27",
+			"/test/e2e/testdata/etcdcluster-3.5.yaml",
+			"v3.3.27",
+		),
+	)
+
 })
+
+func DeleteNamespaceCB(namespace string) func() error {
+	return func() error {
+		return DeleteNamespace(namespace)
+	}
+}
+
+func DeleteNamespace(namespace string) error {
+	By("delete namespace")
+
+	cmd := exec.Command("kubectl", "delete", "namespace", namespace)
+	_, err := utils.Run(cmd)
+
+	return err
+}
+
+func CreateNamespace(namespace string) {
+	By("create namespace", func() {
+		cmd := exec.Command("kubectl", "create", "namespace", namespace)
+		_, err := utils.Run(cmd)
+		ExpectWithOffset(1, err).NotTo(HaveOccurred())
+	})
+
+}
+
+func WaitSTSReady(stsName, namespace string) {
+	By("wait for statefulset is ready", func() {
+		cmd := exec.Command("kubectl", "wait",
+			stsName,
+			"--for", "jsonpath={.status.readyReplicas}=3",
+			"--namespace", namespace,
+			"--timeout", "5m",
+		)
+		_, err := utils.Run(cmd)
+
+		ExpectWithOffset(1, err).NotTo(HaveOccurred())
+	})
+
+}
diff --git a/test/e2e/testdata/etcdcluster-3.3.yaml b/test/e2e/testdata/etcdcluster-3.3.yaml
new file mode 100644
index 00000000..d8bf5b9f
--- /dev/null
+++ b/test/e2e/testdata/etcdcluster-3.3.yaml
@@ -0,0 +1,15 @@
+---
+apiVersion: etcd.aenix.io/v1alpha1
+kind: EtcdCluster
+metadata:
+  name: test
+spec:
+  replicas: 3
+  podTemplate:
+    spec:
+      containers:
+        - name: etcd
+          image: "quay.io/coreos/etcd:v3.3.27"
+#      volumes: []
+#  storage:
+#    emptyDir: {}
diff --git a/test/e2e/testdata/etcdcluster-3.4.yaml b/test/e2e/testdata/etcdcluster-3.4.yaml
new file mode 100644
index 00000000..9e80cce4
--- /dev/null
+++ b/test/e2e/testdata/etcdcluster-3.4.yaml
@@ -0,0 +1,15 @@
+---
+apiVersion: etcd.aenix.io/v1alpha1
+kind: EtcdCluster
+metadata:
+  name: test
+spec:
+  replicas: 3
+  podTemplate:
+    spec:
+      containers:
+        - name: etcd
+          image: "quay.io/coreos/etcd:v3.4.32"
+#      volumes: []
+#  storage:
+#    emptyDir: {}
diff --git a/test/e2e/testdata/etcdcluster-3.5.yaml b/test/e2e/testdata/etcdcluster-3.5.yaml
new file mode 100644
index 00000000..71bf3f38
--- /dev/null
+++ b/test/e2e/testdata/etcdcluster-3.5.yaml
@@ -0,0 +1,15 @@
+---
+apiVersion: etcd.aenix.io/v1alpha1
+kind: EtcdCluster
+metadata:
+  name: test
+spec:
+  replicas: 3
+  podTemplate:
+    spec:
+      containers:
+        - name: etcd
+          image: "quay.io/coreos/etcd:v3.5.11"
+#      volumes: []
+#  storage:
+#    emptyDir: {}
diff --git a/test/e2e/testdata/etcdcluster-simple.yaml b/test/e2e/testdata/etcdcluster-simple.yaml
new file mode 100644
index 00000000..f1bff9e4
--- /dev/null
+++ b/test/e2e/testdata/etcdcluster-simple.yaml
@@ -0,0 +1,7 @@
+---
+apiVersion: etcd.aenix.io/v1alpha1
+kind: EtcdCluster
+metadata:
+  name: test
+spec:
+  replicas: 3
diff --git a/test/e2e/testdata/kind.yaml b/test/e2e/testdata/kind.yaml
new file mode 100644
index 00000000..afe81483
--- /dev/null
+++ b/test/e2e/testdata/kind.yaml
@@ -0,0 +1,4 @@
+kind: Cluster
+apiVersion: kind.x-k8s.io/v1alpha4
+networking:
+  kubeProxyMode: "ipvs"