add script for releasing a Docker image

Dockerfile

@@ -0,0 +1,24 @@
+# Copyright 2020 The Kubermatic Kubernetes Platform contributors.
+#
+# 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.
+
+FROM golang:1.14-alpine as builder
+
+WORKDIR /app/
+COPY . .
+RUN go build
+
+FROM alpine:3.12
+
+COPY --from=builder /app/boilerplate .
+ENTRYPOINT ["/boilerplate"]

hack/ci/release-docker.sh

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+#!/usr/bin/env bash
+
+# Copyright 2020 The Kubermatic Kubernetes Platform contributors.
+#
+# 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.
+
+# This script creates the Docker images on quay.io. Docker is not handled
+# by goreleaser because of our internal CI infrastructure and separation
+# of credentials.
+
+set -euo pipefail
+
+cd $(dirname $0)/../..
+
+repo="quay.io/kubermatic-labs/boilerplate"
+tag="$(git describe --tags --exact-match)"
+image="$repo:$tag"
+
+set -x
+docker build -t "$image" .
+docker push "$image"