Docker-Compose API Call and Endpoint Containerized

Question

Using docker-compose I've got multiple containers running - one of them is the profiler container that calls an API, the other container apiconnection should be receiving the call and sending information back. However when I run the compose file it always returns Get http://apiconnection:8080/maccaption: dial tcp: lookup apiconnection on 127.0.0.11:53: no such host on the Profiler container at the http.DefaultClient.Do line.

This is a sample of my compose file:

apiConnection:
 image: apiconnection:1.0
 ports:
  - "8080:8080"
 networks: 
  - maccaptionNet
profiler:
  image: profiler:1.0
  networks: 
   - maccaptionNet
  depends_on:
   - "apiConnection"

I'm calling the api in my profiler image like so - it's erroring on DefaultClient:

url := "http://apiconnection:8080/maccaption"

req, err := http.NewRequest("GET", url, nil)
if err != nil {
    log.Fatal(err)
}

res, err := http.DefaultClient.Do(req)
if err != nil {
    fmt.Println("Line 27")
    log.Fatal(err)
}

body, err := ioutil.ReadAll(res.Body)
if err != nil {
    fmt.Println("Line 33")
    log.Fatal(err)
}

If I modify the url := "http://apiconnection:8080/maccaption" to look at localhost like this url := "http://localhost:8080/maccaption" it changes to connect refused, but I don't think I should be looking at localhost, I need to look at the Docker container don't I?

I'm setting the url as a connection to the docker container and using the ports I've assigned in the docker-compose file. and receiving the request in my apiconnection image like this:

    r := mux.NewRouter()

r.HandleFunc("/maccaption", handleMaccaption).Methods("GET")

http.ListenAndServe(":8080", r)

All it should be doing now is starting up and making a single request to prove that it is working and returning some json information. This code works outside of docker, replacing the container name in the url variable with localhost. But I cannot get it running within docker.

I've looked at these other sources for assistance but to no avail: how to call api endpoint inside docker container? Making a REST Call to Endpoint in Dockers Docker-compose internal communication using endpoints

Any pointers would be greatly appreciated - thank you!

**EDIT - to fix my wonky code formatting

Answer 1

For anyone who's attempting to do something like this in the future: the above code actually does work. But where I was going wrong was that in my url := "http://apiconnection:8080/maccaption" I was referring to the image name instead of the service name I've defined in the docker-compose.

changing the url to look at the service name instead of the image name corrected the issue and I'm now able to make API calls within my dockerized environment.