# Vert.x Discovery Bridge - Docker Links

This discovery bridge imports services from Docker Links into the Vert.x service discovery.

When you link a Docker container to another Docker container, Docker injects a set of environment variables. This bridge analyzes these environment variables and imports service record for each link. The service type is deduced from the `service.type` label. If not set, the service is imported as `unknown`. Only `http-endpoint` are supported for now.

As the links are created when the container starts, the imported records are created when the bridge starts and do not change afterwards.

## Using the bridge

To use this Vert.x discovery bridge, add the following dependency to the dependencies section of your build descriptor:

- Maven (in your `pom.xml`):

    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-service-discovery-bridge-docker-links</artifactId>
      <version>3.3.3</version>
    </dependency>

- Gradle (in your `build.gradle` file):

    compile 'io.vertx:vertx-service-discovery-bridge-docker-links:3.3.3'

Then, when creating the service discovery, registers this bridge as follows:

    require 'vertx-service-discovery/service_discovery'
    VertxServiceDiscovery::ServiceDiscovery.create(vertx).register_service_importer(Java::IoVertxServicediscoveryDocker::DockerLinksServiceImporter.new(), {
    })

The bridge does not need any further configuration.