Fix old tag of custom error pages used in example (#7460)

* Fix old tag of custom error pages used in example

* Move nginx-errors to k8s registry

Since the setup for the custom-error-messages was really different from
the other images that are build using cloudbuild, I changed it to "fit
in better"

* Use Go version 1.17 for custom-error-pages

Since Go >= 1.16 required the use of modules, I also initialized the module using the name k8s.io/ingress-nginx/custom-error-pages

images/custom-error-pages/rootfs/Dockerfile

@@ -1,4 +1,4 @@
-# Copyright 2017 The Kubernetes Authors. All rights reserved.
+# Copyright 2021 The Kubernetes Authors. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -12,10 +12,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM BASEIMAGE
+FROM golang:1.17-alpine as builder
+RUN apk add git
 
-CROSS_BUILD_COPY qemu-QEMUARCH-static /usr/bin/
+WORKDIR /go/src/k8s.io/ingress-nginx/images/custom-error-pages
 
-COPY . /
+COPY . .
 
-CMD ["/custom-error-pages"]
+RUN go get . && \
+    CGO_ENABLED=0 go build -a -installsuffix cgo \
+	-ldflags "-s -w" \
+	-o nginx-errors .
+
+# Use distroless as minimal base image to package the binary
+# Refer to https://github.com/GoogleContainerTools/distroless for more details
+FROM gcr.io/distroless/static:nonroot
+
+COPY --from=builder /go/src/k8s.io/ingress-nginx/images/custom-error-pages/nginx-errors /
+USER nonroot:nonroot
+
+CMD ["/nginx-errors"]