How to use an embedded redis server with Micronaut

Micronaut provides support to use an embedded redis server which can be handy for running your tests.

To run an embedded redis server you need to include the embedded redis dependency in your build.gradle file.

testImplementation "com.github.kstyrc:embedded-redis:0.6"

This will automatically start and the shutdown an embedded instance of Redis if none is available for the configured Redis URI.

Micronaut achieves this by adding EmbeddedRedisServer which implements BeanCreatedEventListener and listens for the creation of the redis configuration. It checks to see if redis is configured to use localhost and if the port is available. If that is the case, an embedded Redis instance is started.

...
 if (StringUtils.isNotEmpty(host) && host.equals("localhost") && SocketUtils.isTcpPortAvailable(port)) {
           RedisServerBuilder builder = embeddedConfiguration.builder;
           builder.port(port);
           builder.setting(DEFAULT\_MAXMEMORY\_SETTING);
           redisServer = builder.build();
           redisServer.start();

 }
 ...

So essentially all you need to get this working is configuring your redis.uri in application-test.yml to use localhost and a random port as shown below:

redis.uri: redis://localhost:${random.port}/0

An example project using Micronaut 2.1.1 is available on github.