refactor: wait-shutdown preStop hook is not necessary

/wait-shutdown preStop script's only job is to send SIGTERM to nginx-ingress-controller,
which is PID 1, so it's the same with or without in Kubernetes environments.

See #6287 for discussion.

Author: motoki317

build/build.sh

@@ -57,13 +57,3 @@ ${GO_BUILD_CMD} \
   -X ${PKG}/version.REPO=${REPO_INFO}" \
   -buildvcs=false \
   -o "${TARGETS_DIR}/dbg" "${PKG}/cmd/dbg"
-
-echo "Building ${PKG}/cmd/waitshutdown"
-
-${GO_BUILD_CMD} \
-  -trimpath -ldflags="-buildid= -w -s \
-  -X ${PKG}/version.RELEASE=${TAG} \
-  -X ${PKG}/version.COMMIT=${COMMIT_SHA} \
-  -X ${PKG}/version.REPO=${REPO_INFO}" \
-  -buildvcs=false \
-  -o "${TARGETS_DIR}/wait-shutdown" "${PKG}/cmd/waitshutdown"

charts/ingress-nginx/README.md

@@ -372,7 +372,7 @@ metadata:
 | controller.keda.triggers | list | `[]` |  |
 | controller.kind | string | `"Deployment"` | Use a `DaemonSet` or `Deployment` |
 | controller.labels | object | `{}` | Labels to be added to the controller Deployment or DaemonSet and other resources that do not have option to specify labels # |
-| controller.lifecycle | object | `{"preStop":{"exec":{"command":["/wait-shutdown"]}}}` | Improve connection draining when ingress controller pod is deleted using a lifecycle hook: With this new hook, we increased the default terminationGracePeriodSeconds from 30 seconds to 300, allowing the draining of connections up to five minutes. If the active connections end before that, the pod will terminate gracefully at that time. To effectively take advantage of this feature, the Configmap feature worker-shutdown-timeout new value is 240s instead of 10s. # |
+| controller.lifecycle | object | `{}` |  |
 | controller.livenessProbe.failureThreshold | int | `5` |  |
 | controller.livenessProbe.httpGet.path | string | `"/healthz"` |  |
 | controller.livenessProbe.httpGet.port | int | `10254` |  |

charts/ingress-nginx/values.yaml

@@ -945,18 +945,7 @@ controller:
       #   annotations:
       #     description: Too many 4XXs
       #     summary: More than 5% of all requests returned 4XX, this requires your attention
-  # -- Improve connection draining when ingress controller pod is deleted using a lifecycle hook:
-  # With this new hook, we increased the default terminationGracePeriodSeconds from 30 seconds
-  # to 300, allowing the draining of connections up to five minutes.
-  # If the active connections end before that, the pod will terminate gracefully at that time.
-  # To effectively take advantage of this feature, the Configmap feature
-  # worker-shutdown-timeout new value is 240s instead of 10s.
-  ##
-  lifecycle:
-    preStop:
-      exec:
-        command:
-          - /wait-shutdown
+  lifecycle: {}
   priorityClassName: ""
 # -- Rollback limit
 ##

cmd/waitshutdown/main.go

@@ -43,7 +43,6 @@ COPY --chown=www-data:www-data etc /etc
 
 COPY --chown=www-data:www-data bin/${TARGETARCH}/dbg /
 COPY --chown=www-data:www-data bin/${TARGETARCH}/nginx-ingress-controller /
-COPY --chown=www-data:www-data bin/${TARGETARCH}/wait-shutdown /
 
 # Fix permission during the build to avoid issues at runtime
 # with volumes (custom templates)

rootfs/Dockerfile

@@ -65,7 +65,6 @@ COPY --chown=www-data:www-data etc /chroot/etc
 
 COPY --chown=www-data:www-data bin/${TARGETARCH}/dbg /
 COPY --chown=www-data:www-data bin/${TARGETARCH}/nginx-ingress-controller /
-COPY --chown=www-data:www-data bin/${TARGETARCH}/wait-shutdown /
 COPY --chown=www-data:www-data nginx-chroot-wrapper.sh /usr/bin/nginx
 
 WORKDIR /chroot/etc/nginx

rootfs/Dockerfile-chroot

@@ -41,16 +41,14 @@ var _ = framework.IngressNginxDescribe("[Shutdown] Grace period shutdown", func(
 				if strings.Contains(v, "--shutdown-grace-period") {
 					continue
 				}
-
 				args = append(args, v)
 			}
-
 			args = append(args, "--shutdown-grace-period=90")
 			deployment.Spec.Template.Spec.Containers[0].Args = args
-			cmds := []string{"/wait-shutdown"}
-			deployment.Spec.Template.Spec.Containers[0].Lifecycle.PreStop.Exec.Command = cmds
+
 			grace := int64(3600)
 			deployment.Spec.Template.Spec.TerminationGracePeriodSeconds = &grace
+
 			_, err := f.KubeClientSet.AppsV1().Deployments(f.Namespace).Update(context.TODO(), deployment, metav1.UpdateOptions{})
 			return err
 		})