Create a self signed TLS certificate for Local Development

gistfile1.txt

#!/bin/bash

# Exit on failure
set -e

# Create the root key
openssl genrsa -out ./root.key 2048

# Generate the root certificate
openssl req -x509 -new -nodes -key ./root.key -sha256 -days 3650 -out ./root.crt -subj /C=XX/ST=LocalHost/L=LocalHost/O=LocalHost/OU=LocalHost/CN=localhost

# Generate the localhost key
openssl genrsa -out ./localhost.key 2048

# Create a CSR from the localhost key
openssl req -new -key ./localhost.key -out ./localhost.csr -subj /C=XX/ST=LocalHost/L=LocalHost/O=LocalHost/OU=LocalHost/CN=localhost

# Create the 'extension' file - this is used to add the additional DNS names (i.e. the wildcards)
cat > ./localhost.ext << EOF
authorityKeyIdentifier=keyid,issuer
basicConstraints=CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names
[alt_names]
DNS.1 = localhost
DNS.2 = *.example
DNS.3 = *.invalid
DNS.4 = *.localhost
DNS.5 = *.test
EOF

# Generate the localhost certificate, signed by the root certificate, using the extension file
openssl x509 -req -in ./localhost.csr -CA ./root.crt -CAkey ./root.key -CAcreateserial -out ./localhost.crt -days 3650. -sha256 -extfile ./localhost.ext