gencerts.sh

#!/bin/bash

# Copyright 2017 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.

# Generates the a CA cert, a server key, and a server cert signed by the CA. 
# reference: https://github.com/kubernetes/kubernetes/blob/master/plugin/pkg/admission/webhook/gencerts.sh
set -e

CN_BASE="generic_webhook_admission_example"

cat > server.conf << EOF
[req]
req_extensions = v3_req
distinguished_name = req_distinguished_name
[req_distinguished_name]
[ v3_req ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
extendedKeyUsage = clientAuth, serverAuth
EOF

# Create a certificate authority
openssl genrsa -out caKey.pem 2048
openssl req -x509 -new -nodes -key caKey.pem -days 100000 -out caCert.pem -subj "/CN=${CN_BASE}_ca"

# Create a server certiticate
openssl genrsa -out serverKey.pem 2048
# Note the CN is the DNS name of the service of the webhook.
openssl req -new -key serverKey.pem -out server.csr -subj "/CN=webhook.default.svc" -config server.conf
openssl x509 -req -in server.csr -CA caCert.pem -CAkey caKey.pem -CAcreateserial -out serverCert.pem -days 100000 -extensions v3_req -extfile server.conf

outfile=certs.go

cat > $outfile << EOF
/*
Copyright 2017 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.
*/

EOF

echo "// This file was generated using openssl by the gencerts.sh script" >> $outfile
echo "" >> $outfile
echo "package main" >> $outfile
for file in caKey caCert serverKey serverCert; do
	data=$(cat ${file}.pem)
	echo "" >> $outfile
	echo "var $file = []byte(\`$data\`)" >> $outfile
done

# Clean up after we're done.
rm *.pem
rm *.csr
rm *.srl
rm *.conf