This is documentation for the next version of K6. For the latest stable release, go to the latest version.
SSL/TLS version and ciphers
To support testing specific client configurations, you can specify a version or range of versions of SSL/TLS that are allowed for a connection. You can as also specify which cipher suites are allowed for that connection.
⚠️ Reg. ciphers and TLS 1.3
Due to limitations in the underlying go implementation, changing the ciphers for TLS 1.3 is not supported and will do nothing.
Limiting SSL/TLS version
To limit the k6 to a specific SSL/TLS version, use a global configuration option:
import http from 'k6/http';
export const options = {
tlsVersion: http.TLS_1_2,
};
export default function () {
http.get('https://badssl.com');
}
You can also accept a range of SSL/TLS versions:
import http from 'k6/http';
export const options = {
tlsVersion: {
min: http.SSL_3_0,
max: http.TLS_1_2,
},
};
export default function () {
http.get('https://badssl.com');
}
Versions available to choose from
Here’s the list of available SSL/TLS versions that you can choose from, ordered from oldest version to latest.
http.SSL_3_0
http.TLS_1_0
http.TLS_1_1
http.TLS_1_2
http.TLS_1_3
Limiting cipher suites
To limit the cipher suites that k6 is allowed to use, there’s a global configuration option. You choose a list of allowed ciphers:
import http from 'k6/http';
export const options = {
tlsCipherSuites: ['TLS_RSA_WITH_RC4_128_SHA', 'TLS_RSA_WITH_AES_128_GCM_SHA256'],
};
export default function () {
http.get('https://badssl.com');
}
Checking SSL/TLS version and cipher suite used in requests
You can also check which SSL/TLS version and ciphers were used.
To do so, look at the tls_version
and tls_cipher_suite
response object properties.
import http from 'k6/http';
import { check } from 'k6';
export default function () {
const res = http.get('https://sha256.badssl.com');
check(res, {
'is TLSv1.2': (r) => r.tls_version === http.TLS_1_2,
'is sha256 cipher suite': (r) => r.tls_cipher_suite === 'TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256',
});
}
Cipher suites available to choose from
Here’s a list of available SSL/TLS cipher suites:
TLS_RSA_WITH_RC4_128_SHA
TLS_RSA_WITH_3DES_EDE_CBC_SHA
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_AES_128_GCM_SHA256
TLS_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_ECDSA_WITH_RC4_128_SHA
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_RSA_WITH_RC4_128_SHA
TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
⚠️ Differences depending on k6 build
This list reflects the available cipher suites in the latest official build. If you are using a custom-built k6, the available cipher suites will depend on the Go version you compiled it with, see https://golang.org/pkg/crypto/tls/#pkg-constants.