create selfsigned certificate with subject alternative name

1_createRootCA.sh

#!/usr/bin/env bash
mkdir ~/ssl/
openssl genrsa -des3 -out ~/ssl/rootCA.key 2048
openssl req -x509 -new -nodes -key ~/ssl/rootCA.key -sha256 -days 1024 -out ~/ssl/rootCA.pem

2_createcertificate.sh

#!/usr/bin/env bash
sudo openssl req -new -sha256 -nodes -out server.csr -newkey rsa:2048 -keyout server.key -config <( cat server_csr.cnf )

sudo openssl x509 -req -in server.csr -CA ~/ssl/rootCA.pem -CAkey ~/ssl/rootCA.key -CAcreateserial -out server.crt -days 500 -sha256 -extfile v3.ext

3_server.csr.cnf

[req]
default_bits = 2048
prompt = no
default_md = sha256
distinguished_name = dn
 
[dn]
C=US
ST=New York
L=Rochester
O=End Point
OU=Testing Domain
emailAddress=your-administrative-address@your-awesome-existing-domain.com
CN = localhost

4_v3.ext

authorityKeyIdentifier=keyid,issuer
basicConstraints=CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names

[alt_names]
DNS.1 = localhost

5_test.sh

openssl x509 -text -in server.crt -noout

6_expected_result.txt

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 17237690484651272016 (0xef38942aa5c52750)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=US, ST=New York, L=Rochester, O=End Point, CN=localhost/your-administrative-address@your-awesome-existing-domain.com
        Validity
            Not Before: Apr 23 16:07:38 2017 GMT
            Not After : Sep  5 16:07:38 2018 GMT
        Subject: C=US, ST=New York, L=Rochester, O=End Point, OU=Testing Domain/emailAddress=your-administrative-address@your-awesome-existing-domain.com, CN=localhost
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:b2:e3:bd:ed:28:04:85:ea:75:ee:d2:82:e1:eb:
                    f5:5f:7f:cf:7e:cb:70:de:86:9f:75:7c:f3:71:e7:
                    da:16:fb:bc:1f:89:bc:47:08:77:ca:33:20:f1:c1:
                    9e:e3:20:8d:89:14:7e:c1:0a:12:d2:59:24:56:9b:
                    77:90:5f:69:d1:a5:f1:00:38:93:1b:a7:75:f1:33:
                    e2:da:dc:32:a9:0a:85:7d:9a:20:81:ca:20:ee:86:
                    ce:e2:a0:52:d2:ab:11:34:e5:52:99:3a:81:c6:9f:
                    6b:0f:6a:02:2b:38:a6:84:c9:ba:fa:9b:ef:0a:89:
                    22:4b:79:86:3c:bd:44:a5:54:fb:cf:4d:8b:d1:44:
                    03:35:22:de:69:77:c8:fa:4d:c6:01:25:08:9f:4d:
                    a9:79:7a:aa:ca:03:b6:e4:51:57:22:27:5f:a7:12:
                    11:f3:e6:00:29:f6:58:be:2c:aa:09:e4:06:45:d9:
                    3f:75:a7:f0:75:bd:2b:a6:bb:6d:ad:93:bb:b9:1d:
                    d7:75:39:4e:9b:1d:0e:39:cc:17:74:88:f7:e2:b7:
                    85:12:96:e0:cb:42:56:d0:11:e0:84:86:e5:14:a5:
                    f2:6d:43:5d:f9:59:ae:61:7f:01:ae:95:b8:92:27:
                    1d:1c:02:d7:ad:fb:ee:f6:25:38:60:c8:41:20:17:
                    80:69
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Authority Key Identifier: 
                keyid:5A:8D:89:64:BD:F2:3E:C2:D7:7B:BE:17:84:F4:29:E8:C5:32:35:34

            X509v3 Basic Constraints: 
                CA:FALSE
            X509v3 Key Usage: 
                Digital Signature, Non Repudiation, Key Encipherment, Data Encipherment
            X509v3 Subject Alternative Name: 
                DNS:localhost
    Signature Algorithm: sha256WithRSAEncryption
         27:1d:d6:84:50:33:d2:ff:b1:06:9b:fa:f1:40:7d:47:11:bc:
         f7:80:fd:26:87:0e:91:9f:14:be:1f:1d:9b:32:d1:fb:d6:8d:
         af:30:8a:88:38:8c:1c:bf:77:98:8e:cd:06:48:82:fa:09:b9:
         3c:0d:38:c4:a0:da:b7:4d:f5:81:5f:5a:76:04:61:f8:c2:1a:
         17:ad:56:7c:72:ba:f6:65:7f:7f:e7:5e:b2:34:ba:13:23:57:
         84:f1:c5:ca:dd:5b:55:69:95:71:44:4a:30:53:61:5c:ad:47:
         d8:9c:d5:a2:1b:18:2d:e1:19:35:3e:3f:b2:7e:fd:bf:f3:d0:
         45:dc:f5:57:f0:1b:cd:70:1b:e0:34:de:27:98:89:b4:a5:25:
         a5:6c:29:c3:89:a6:a5:c5:4d:f5:45:3b:47:8e:13:45:23:07:
         5e:d6:59:0d:96:c6:a3:f0:c5:3d:ee:a8:ad:36:96:43:13:a1:
         b8:55:f6:c7:10:7e:8f:5d:09:ef:61:17:2a:9c:3b:50:28:c8:
         e3:8d:a6:34:06:50:d4:3e:d5:17:ea:7d:31:97:d3:ee:df:b5:
         23:66:5e:22:b7:e4:fa:36:4f:9a:d5:f0:a3:f9:b4:2b:27:02:
         0b:41:94:d1:a1:f7:1b:2c:7e:74:e6:14:c3:b5:67:15:d2:ca:
         02:77:57:a6