Starting TestContainers and modifying config at startup in a Micronaut project

IntegrationSpec.groovy

package com.example


import groovy.util.logging.Slf4j
import io.micronaut.test.support.TestPropertyProvider
import org.testcontainers.containers.GenericContainer
import org.testcontainers.utility.DockerImageName
import spock.lang.Specification

@Slf4j
abstract class IntegrationSpec extends Specification implements TestPropertyProvider {

    static GenericContainer redisContainer = new GenericContainer(DockerImageName.parse("redis")).withExposedPorts(6379)

    static {
        redisContainer.start()
    }

    @Override
    Map<String, String> getProperties() {
        String redisUrl = "redis://${redisContainer.host}:${redisContainer.firstMappedPort}"
        log.debug("Providing redis connection URL ${redisUrl}")
        [
            "redis.uri": redisUrl
        ]
    }
}