Configure the SSLContext, SNI, keystore and truststore

KeyManager and TrustManager

By default, Gatling uses:

  • the JVM’s default KeyManager
  • a fake TrustManager that trust everything. The reason is we want to work out of the box with any server certificate, even when it’s issued from a custom Authority. Gatling is a load test tool, not your application managing sensible data to be protected against a man-in-the-middle.

You can override this behavior, typically for forcing your own KeyStore because your server requires mutual TLS. You’ll have to edit the ssl block in gatling.conf.

Gatling accepts files in jks and p12 formats.


By default, each virtual user will have its own SSLContext and SSLSession. This behavior is realistic when it comes to simulating web traffic so your server has to deal with the proper number of SSLSession.

You can only have a shared SSLContext if you decide to shareConnections.

Disabling OpenSSL

By default, Gatling uses BoringSSL (Google’ fork of OpenSSL) to perform TLS. This implementation is more efficient than the JDK’s one, especially on JDK8. It’s also the only supported solution for HTTP/2 in Gatling with JDK8.

If you want to revert to using JDK’s implementation, you can set the gatling.http.ahc.useOpenSsl property to false in gatling.conf

Disabling SNI

By default, since JDK7, JDK enables SNI by default. This can cause TLS handshake exceptions, such as handshake alert: unrecognized_name when server names are not properly configured on the server side. Browsers are more loose than JDK regarding this.

If you want to disable SNI, you can set the gatling.http.ahc.enableSni property to false in gatling.conf.


Gatling supports TLSv1.3 as long as your Java version supports it as well, which means running at least 1.8.0_262. TLSv1.3 is enabled by default.

Configuring KeyStore and TrustStore

Default Gatling TrustStore is very permissive and doesn’t validate certificates, meaning that it works out of the box with self-signed certificates.

You can pass your own keystore and truststore in gatling.conf.

perUserKeyManagerFactory can be used to set the KeyManagerFactory for each virtual user.

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