class EcrLoginTask extends DefaultTask {
    String accessKey
    String secretCode
    String region
    String registryId

    @TaskAction
    String getPassword() {
        AmazonECR ecrClient = AmazonECRClient.builder()
                .withRegion(Regions.fromName(region))
                .withCredentials(new AWSStaticCredentialsProvider(new BasicAWSCredentials(accessKey, secretCode))).build()
        GetAuthorizationTokenResult authorizationToken = ecrClient.getAuthorizationToken(
                new GetAuthorizationTokenRequest().withRegistryIds(registryId))
        String token = authorizationToken.getAuthorizationData().get(0).getAuthorizationToken()
        System.setProperty("DOCKER_PASS", token) // Will this work ?
        return token
    }

}

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.amazonaws:aws-java-sdk-ecr:1.11.244'
        classpath 'com.bmuschko:gradle-docker-plugin:3.2.1'
    }
}



docker {
    url = "tcp://remote-docker-host:2375"
    registryCredentials {
        username = 'AWS'
        password = System.getProperty("DOCKER_PASS")    // Need to provide at runtime !!!
        url = 'https://123456789123.dkr.ecr.eu-west-1.amazonaws.com'
    }
}

task getECRPassword(type: EcrLoginTask) {
    accessKey AWS_KEY
    secretCode AWS_SECRET
    region AWS_REGION
    registryId '139539380579'
}

task dbuild(type: DockerBuildImage) {
    dependsOn build
    inputDir = file(".")
    tag "139539380579.dkr.ecr.eu-west-1.amazonaws.com/n6duplicator"
}

task dpush(type: DockerPushImage) {
    dependsOn dbuild, getECRPassword
    imageName "123456789123.dkr.ecr.eu-west-1.amazonaws.com/n6duplicator"
}