Repackage dockerfile

Dockerfile

# 
# $ tree
# 
# ├── Dockerfile
# └── gcp_envoy_bootstrap.json. --> update and copy the file here.
# To build an image
# $ export IMAGE_NAME=gcr.io/gke-release/asm/proxyv2:1.11.2-asm.17-modified-1
# $ docker build -t  ${IMAGE_NAME} .
# $ docker push ${IMAGE_NAME}

# FROM should include whatver base image you want.
FROM gcr.io/gke-release/asm/proxyv2:1.11.2-asm.17
COPY gcp_envoy_bootstrap.json /var/lib/istio/envoy/gcp_envoy_bootstrap_tmpl.json

# The following line ensures that this image will use the gcp file by default.
# In absence of this line, update 
ENV ISTIO_BOOTSTRAP=/var/lib/istio/envoy/gcp_envoy_bootstrap_tmpl.json