Revert "docker: Remove buildx init/install (nmstate#1134)"

This reverts commit 4bb0cd0.

Signed-off-by: Enrique Llorente <ellorent@redhat.com>

hack/build-push-container.docker.sh

@@ -7,6 +7,8 @@ if [ "$SKIP_IMAGE_BUILD" == "true" ]; then
     exit 0
 fi
 
+hack/init-buildx.sh
+
 ARCHS=${ARCHS:-$(go env GOARCH)}
 PLATFORM=""
 

hack/init-buildx.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# Copyright 2020 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -o errexit -o nounset -o pipefail
+
+export DOCKER_CLI_EXPERIMENTAL=enabled
+
+# If there is no buildx let's install it
+if ! docker buildx > /dev/null 2>&1; then
+    mkdir -p ~/.docker/cli-plugins
+    curl -L https://github.com/docker/buildx/releases/download/v0.6.3/buildx-v0.6.3.linux-amd64 --output ~/.docker/cli-plugins/docker-buildx
+    chmod a+x ~/.docker/cli-plugins/docker-buildx
+fi
+
+
+# We can skip setup if the current builder already has multi-arch
+# AND if it isn't the docker driver, which doesn't work
+current_builder="$(docker buildx inspect)"
+# linux/amd64, linux/arm64, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/arm/v7, linux/arm/v6
+if ! grep -q "^Driver: docker$"  <<<"${current_builder}" && \
+     grep -q "linux/amd64" <<<"${current_builder}" && \
+     grep -q "linux/arm64" <<<"${current_builder}"; then
+  exit 0
+fi
+
+
+if ! docker buildx ls | grep -q kubernetes-nmstate-builder; then
+    docker buildx create --driver-opt network=host --use --name=kubernetes-nmstate-builder
+fi