无法从另一个容器连接到ElasticSearch容器

Question

I'm trying to connect to an ElasticSearch container from a Golang container using the official go-elasticsearch api. However when I try and connect to the container I get this error:

Error getting response: dial tcp 172.28.0.2:9200: connect: connection refused

I think it's an issue in the container setup?

docker-compose.yaml

version: "3"
services:
  redis_server:
    image: "redis"
    ports:
      - "6379:6379"
  lambda_server:
    build: .
    ports:
      - "8080:50051"
    depends_on:
      - redis_server
      - elasticsearch
  elasticsearch:
    image: docker.elastic.co/elasticsearch/elasticsearch:7.3.1
    ports:
      - "9200:9200"
      - "9300:9300"      
    environment:
      - xpack.security.enabled=false
      - discovery.type=single-node
      - http.cors.enabled=true
      - http.cors.allow-origin=*

go

tlsConf := &http.Transport{
        TLSClientConfig: &tls.Config{
            Renegotiation: tls.RenegotiateOnceAsClient,
            Certificates:  []tls.Certificate{cer},
        },
    }
cfg := elasticsearch.Config{
        Addresses: []string{
            "http://elasticsearch:9200",
            "http://elasticsearch:9300",
        },
        Transport: tlsConf,
    }
    elasticClient, err = elasticsearch.NewClient(cfg)

    res, err := elasticClient.Info()
    if err != nil {
        log.Fatalf("Error getting response: %s", err)
    }