First sidecar module: OpenTelemetry (#8013)

* remove opentelemetry from main nginx image

* add opentelemetry sidecar image

* handle extra modules in helm chart

* fix running helm chart

* mount the modules volume in the init container

* merge the mounted folder

* fix the otel image

* fix licence year

* fix cloudbuild image

* use the same nginx version as in the main image

* only retrieve /etc/nginx/modules for now

images/opentelemetry/rootfs/Dockerfile

@@ -0,0 +1,28 @@
+# 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.
+# 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 alpine:3.14.2 as builder
+
+COPY . /
+
+RUN apk update \
+	&& apk upgrade \
+	&& apk add -U bash \
+	&& /build.sh
+
+FROM busybox:latest 
+
+COPY --from=builder init_module.sh /usr/local/bin/init_module.sh
+COPY --from=builder /etc/nginx/modules /etc/nginx/modules