6.27 HTTP/2 Support

Since Micronaut 2.x, Micronaut’s Netty-based HTTP server can be configured to support HTTP/2.

Configuring the Server for HTTP/2

The first step to doing so is setting the supported HTTP version is the server configuration:

Enabling HTTP/2 Support

micronaut:
  server:
      http-version: 2.0

With this configuration in place Micronaut will enable support for the h2c protocol (see HTTP/2 over cleartext) which is fine for development.

Since browsers don’t support h2c and in general HTTP/2 over TLS (the h2 protocol) is recommended for production you should enable HTTPS support support. For development this can be done with:

Enabling h2 Protocol Support

micronaut:
  ssl:
      enabled: true
      buildSelfSigned: true
  server:
      http-version: 2.0

For production, see the configuring HTTPS section of the documentation.

Note that if you deployment environment is JDK 8 or if you wish for improved support for OpenSSL you will need to define the following dependencies on Netty Tomcat Native:

runtimeOnly("io.netty:netty-tcnative:2.0.29.Final")

<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-tcnative</artifactId>
    <version>2.0.29.Final</version>
    <scope>runtime</scope>
</dependency>

runtimeOnly("io.netty:netty-tcnative-boringssl-static:2.0.29.Final")

<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-tcnative-boringssl-static</artifactId>
    <version>2.0.29.Final</version>
    <scope>runtime</scope>
</dependency>

In addition to a dependency on the appropriate native library for your architecture. For example:

Configuring Tomcat Native

runtimeOnly "io.netty:netty-tcnative-boringssl-static:2.0.29.Final:${Os.isFamily(Os.FAMILY_MAC) ? 'osx-x86_64' : 'linux-x86_64'}"

See the documentation on Tomcat Native for more information.

HTTP/2 Clients

By default Micronaut’s HTTP client is configured to support HTTP 1.1. To enable support for HTTP/2 you can do so globally by setting the supported HTTP version if configuration:

Enabling HTTP/2 in Clients

micronaut:
    http:
        client:
            http-version: 2.0

Or by specifying the HTTP version to use when injecting the client:

Injecting a HTTP/2 Client

@Inject
@Client(httpVersion=HttpVersion.HTTP_2_0)
RxHttpClient client;