We generate certificates that are intended to be used for server authentication in a couple of places:

- `bin/elasticsearch-certutil http` command  ( See `CertGenUtils.generateSignedCertificate` in `HttpCertificateCommand` )
- TLS auto-configuraion for node startup ( see [`AutoConfigureNode`](https://github.com/elastic/elasticsearch/blob/814f7f9f52cb8c05db6465b9bfc818ea5d76c575/x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/AutoConfigureNode.java#L454) )

In these cases we know that the certificate is meant to be used for server authentication, so we can set Extended Key Usage extension to `1.3.6.1.5.5.7.3.1`
x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/HttpCertificateCommand.java
}
    private void createZipDirectory(ZipOutputStream zip, String name) throws IOException {
        ZipEntry entry = new ZipEntry(name + "/");
        assert entry.isDirectory();
        zip.putNextEntry(entry);
    }
    private void writeCertificateAndKeyDetails(
        ZipOutputStream zip,
        String dirName,
        CertOptions cert,
        CertificateTool.CAInfo ca,
        char[] password,
        Environment env
    ) {
        
        try {
            final KeyPair keyPair = CertGenUtils.generateKeyPair(cert.keySize);
            final GeneralNames sanList = CertificateTool.getSubjectAlternativeNamesValue(cert.ipNames, cert.dnsNames, List.of());
            final boolean hasPassword = password != null && password.length > 0;
            
            
            if (ca == null) {
                
                final PKCS10CertificationRequest csr = CertGenUtils.generateCSR(keyPair, cert.subject, sanList);
                final String csrFile = "http-" + cert.name + ".csr";
                final String keyFile = "http-" + cert.name + ".key";
                final String certName = "http-" + cert.name + ".crt";
                final String ymlFile = "sample-elasticsearch.yml";
                final Map<String, String> substitutions = buildSubstitutions(
                    env,