generate SAN-enabled self-signed cert

self-signed-cert.sh

#!/bin/sh

if [ -z "$2" ]; then
    echo "Syntax: $0 <commonname> <subjectaltnames>"
    echo ""
    echo "  <subjectaltname> example: 'DNS:example.com,DNS:www.example.com,IP:172.16.32.1'"
    echo ""
    exit 1
fi

common_name="$1"
subject_altname="$2"

### Legacy method, does not support subjectAltName:
#openssl req -x509 \
#  -newkey rsa:4096 \
#  -keyout "${common_name}.key" \
#  -out "${common_name}.crt" \
#  -sha256 \
#  -days 3650 \
#  -nodes \
#  -subj "/C=US/ST=AK/L=SomeCity/O=Org/OU=Org/CN=${common_name}"

### New method, supports subjectAltName without config files:
openssl req -x509 \
  -new \
  -nodes \
  -sha256 \
  -days 3650 \
  -subj "/C=US/ST=AK/L=SomeCity/O=Org/OU=Org/CN=${common_name}" \
  -addext  "subjectAltName = ${subject_altname}" \
  -newkey rsa:4096 \
  -keyout "${common_name}.key" \
  -out "${common_name}.crt"