Generate a self-signed TLS cert with subjectAltNames wildcards

gistfile1.txt

$ cat openssl.cnf

[ req ]
default_bits       = 2048
distinguished_name = req_distinguished_name
x509_extensions = v3_ca

[ req_distinguished_name ]
countryName                = Country Name (2 letter code)
countryName_default        = CA
stateOrProvinceName        = State or Province Name (full name)
stateOrProvinceName_default = British Columbia
localityName               = City
localityName_default       = Vancouver
organizationName           = Org
organizationName_default   = Institution Green Inc
commonName                 = Common Name (e.g. server FQDN or YOUR name) # *.example.com
commonName_max             = 64
emailAddress               = Email Address
emailAddress_max           = 64

[ v3_ca ]
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid:always,issuer
basicConstraints = critical,CA:true
subjectAltName = @alt_names

[alt_names]
DNS.1   = *.example.com
DNS.2   = foo.example.com
DNS.3   = bar.example.com
DNS.4   = baz.example.com

$ openssl req -x509 -out ./cert.crt -newkey rsa:2048 
  -nodes -sha256 -days 1300 -keyout ./build/cert.key -config ./openssl.cnf

$ openssl x509 -in ./cert.crt -text -noout