Create CSR (Certificate Sign Request)

Create CSR config file

export fqdn="project.customer.com"
vi ${fqdn}.csr.conf

content

[ req ]
default_bits       = 2048
default_md         = sha256
prompt             = no
encrypt_key        = no
distinguished_name = dn
req_extensions     = req_ext

[ dn ]
C  = country-abbreviation
ST = project
L  = location
O  = org
OU = org-unit
CN = project.customer.com

[ req_ext ]
subjectAltName = @alt_names

[ alt_names ]
DNS.1 =     www.project.customer.com
DNS.2 =     stg-project.customer.com
DNS.3 = www.stg-project.customer.com

Generate CSR

export fqdn="project.customer.com"
openssl req \
    -new \
    -newkey rsa:4096 \
    -nodes \
    -config ${fqdn}.csr.conf \
    -keyout ${fqdn}.key \
    -out    ${fqdn}.csr

Verify CSR

openssl req \
    -in ${fqdn}.csr \
    -noout \
    -text