How to connect to Elasticsearch with Docker Compose - elasticsearch

Question

I connect from my web app to an Elasticsearch instance using the Java API:
static Optional<Client> getClient(String hostName, int port) {
return getHost(hostName).map(host -> TransportClient.builder().build()
.addTransportAddress(new InetSocketTransportAddress(host, port))
);
}
static Optional<InetAddress> getHost(String hostName) {
InetAddress host = null;
try {
host = InetAddress.getByName(hostName);
} catch (UnknownHostException e) {
LOG.warn("Could not get host: {}", hostName, e);
}
return Optional.ofNullable(host);
}
Before switching to Docker Compose, I started Elasticsearch using
docker run --net=my-network --name=myDb elasticsearch
and my web app using
docker run --net=my-network -p 8080:4567 me/myapp
and sure enough, I could connect to the database using getClient("myDb", 9300).
But now that I've switched to Docker Compose, I don't know how to connect to Elasticsearch. This is my current docker-compose.yml:
version: '2'
services:
my-app:
image: me/myapp
ports:
- "8080:4567"
networks:
- my-network
elasticsearch:
image: elasticsearch
networks:
- my-network
networks:
my-network:
driver: bridge
Understandably, this results in an UnknownHostException since I haven't set the hostname of my Elasticsearch instance in the docker-compose.yml.
How do I do that?

Answer 1

I had to set an alias:
elasticsearch:
image: elasticsearch
networks:
my-network:
aliases:
- myDb
Now I can connect to myDb on port 9300 when calling getClient("myDb", 9300) shown in the question.