gce-startup-script

#!/bin/bash

# metadata prints the value associated with the named metadata key on this VM.
metadata() {
	curl -s http://metadata/computeMetadata/v1/instance/attributes/$1 -H "Metadata-Flavor: Google" >/tmp/meta
	if ! grep 'Error 404' /tmp/meta >/dev/null; then
		cat /tmp/meta
	fi
	rm -f /tmp/meta
}

set -e

# redirector should be the gs:// URL of the go-import-redirector binary.
redirector=$(metadata redirector)

# import should be the import path, like rsc.io/*
# repo should be the repo path, like https://github.com/rsc/*
import=$(metadata import)
repo=$(metadata repo)

# initialize /work with redirector binary
mkdir -p /work
gsutil cp $redirector /work/redirector
chmod +x /work/redirector
cd /work

# if metadata for 'certs' is present, copy certificates from
# <certs>/<host>.crt and <certs>/<host>.key,
# where host is the host name in the import path.
set +e
host=$(echo $import | sed 's;/.*;;')
certs=$(metadata certs)
opt=""
if [ "$certs" != "" ]; then
	opt=-tls
	gsutil cp $certs/$host.crt .
	gsutil cp $certs/$host.key .
fi
letsencrypt=$(metadata letsencrypt)
if [ "$letsencrypt" != "" ]; then
	opt="-letsencrypt=$letsencrypt"
fi

# run redirector in a loop, sleeping 10 seconds between restarts
while true
do
	./redirector $opt "$import" "$repo"
	sleep 10
done >log 2>&1 &
exit 0