I can't use IP address or service name in network communication

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1

I am running a project with docker compose, it consists of 2 containers: client and server

This is the current docker-compose.yaml file:

version: "3.8"
services:
  server:
    build: ./server
    ports:
      - "80:80"
    volumes:
      - ./server:/app
      - /app/node_modules
    env_file:
      - .env
  client:
    build: ./client
    ports:
      - "3000:3000"
    volumes:
      - ./client:/app
      - /app/node_modules
    depends_on:
      - server

In client-side code (a Next.JS app) the HTTP requests URL is set to http://localhost:80/api/v1/ and everything works fine. I am able to access the client in the browser at http://localhost:3000, the client fetches data from the server and renders to the user normally.

However, I wish I could make the client send requests to the server directly through the docker network, and not through localhost as a middleman, so I tried changing the URL from http://localhost:80/api/v1/ to http://server:80/api/v1/

Then I accessed the client through the browser again and, this time, as soon as the client tries to fetch data from the server, I get this error in the console:

::ERR_NAME_NOT_RESOLVED

I checked the network:

henrique@my-project$ sudo docker network ls
NETWORK ID     NAME               DRIVER    SCOPE
6763669621ae   bridge             bridge    local
0b26076b0be2   host               host      local
f4dc395426d2   my-project_default   bridge    local
ffa82867354a   none               null      local

I checked the containers (services):

henrique@my-project$ sudo docker ps --format \
"table {{.ID}}\t{{.Status}}\t{{.Names}}"
CONTAINER ID   STATUS             NAMES
3d8727bc9ca4   Up About an hour   my-project-client-1
59f75f5b39d3   Up About an hour   my-project-server-1

I checked the communication between the 2 containers:

henrique@my-project$ sudo docker exec my-project-client-1 ping my-project-server-1
PING my-project-server-1 (172.30.0.2): 56 data bytes
64 bytes from 172.30.0.2: seq=0 ttl=64 time=0.060 ms
64 bytes from 172.30.0.2: seq=1 ttl=64 time=0.041 ms
64 bytes from 172.30.0.2: seq=2 ttl=64 time=0.048 ms
64 bytes from 172.30.0.2: seq=3 ttl=64 time=0.047 ms
^C

I opened a bash shell inside the client container and checked the communication with the curl command:

/app # curl http://my-project-server-1:80/api/v1/
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Error</title>
</head>
<body>
<pre>Cannot GET /api/v1/</pre>
</body>
</html>

(it worked. This is the expected HTTP response for this endpoint)

I inspected the server container by running sudo docker container inspect my-project-server-1 and then I copied its IP address from the line: "IPAddress": "172.30.0.2",

Finally, I tried setting up the HTTP request URL to http://172.30.0.2:80/api/v1/.

Then, this time, as soon as the client tries to fetch data from the server, the page keeps loading infinitely. There are no errors anywhere.

So, each URL presents a different behavior:

  1. http://localhost:80/api/v1/: works fine

  2. http://server:80/api/v1/: throws error ERR_NAME_NOT_RESOLVED

  3. http://172.30.0.2:80/api/v1/: infinite loading

2

Specifying “container_name” may work.
https://docs.docker.com/compose/compose-file/05-services/#container_name