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/test/java/org/elasticsearch/xpack/security/cli/HttpCertificateCommandTests.java
}
        Path zipRoot = getZipRoot(outFile);
        assertThat(zipRoot.resolve("elasticsearch"), isDirectory());
        final Path p12Path = zipRoot.resolve("elasticsearch/http.p12");
        final Path readmePath = zipRoot.resolve("elasticsearch/README.txt");
        assertThat(readmePath, isRegularFile());
        final String readme = Files.readString(readmePath);
        final Path ymlPath = zipRoot.resolve("elasticsearch/sample-elasticsearch.yml");
        assertThat(ymlPath, isRegularFile());
        final String yml = Files.readString(ymlPath);
        final Tuple<X509Certificate, PrivateKey> certAndKey = readCertificateAndKey(p12Path, password.toCharArray());
        
        verifyCertificate(certAndKey.v1(), certificateName, years, hostNames, ipAddresses);
        assertThat(getRSAKeySize(certAndKey.v1().getPublicKey()), is(HttpCertificateCommand.DEFAULT_CERT_KEY_SIZE));
        assertThat(getRSAKeySize(certAndKey.v2()), is(HttpCertificateCommand.DEFAULT_CERT_KEY_SIZE));
        final X509Certificate caCert = CertParsingUtils.readX509Certificate(caCertPath);
        verifyChain(certAndKey.v1(), caCert);
        
        assertThat(readme, containsString(p12Path.getFileName().toString()));
        assertThat(readme, containsString(ymlPath.getFileName().toString()));
        if ("".equals(password) == false) {
            assertThat(readme, not(containsString(password)));
        }
        assertThat(readme, not(containsString(caPassword)));
        
        assertThat(yml, containsString(p12Path.getFileName().toString()));
        if ("".equals(password) == false) {
            assertThat(yml, not(containsString(password)));
        }
        assertThat(yml, not(containsString(caPassword)));