Unable to Send POST Request from Dockerized Service to Another Dockerized Service

I am working on a project with multiple microservices using Docker Compose. I have two services, matching_service and collaboration_service. The matching_service sends a POST request to the collaboration_service to create a room. However, the request fails with the following error:

Error creating room: request to http://localhost:4000/create-room failed, reason: 
Response from createRoom: undefined
Response from createRoom: {
  status: 500,
  message: 'request to http://localhost:4000/create-room failed, reason: '
}

The matching_service can recieve post request but cannot send a GET or POST request. But the POST api works from postman and other backend services, except matching_service.

docker-compose.yml


matching-service:
    build: ./backend/matching-service # Path to the directory containing the Dockerfile for building the backend/question-service image.
    ports:
      - 3002:3002
      - 8080:8080
    env_file:
      - ./backend/matching-service/.env
    depends_on:
      rabbitmq:
        condition: service_healthy

  rabbitmq:
    image: rabbitmq:3-management
    ports:
      - "5672:5672"
      - "15672:15672"
    healthcheck:
      test: ["CMD", "rabbitmq-diagnostics", "status"]
      interval: 5s
      timeout: 10s
      retries: 5

  collaboration-service:
    build: ./backend/collaboration-service # Path to the directory containing the Dockerfile for building the backend/user-service image.
    ports:
      - 4000:4000 # Maps port 3001 on the host to port 3001 in the container, making the app accessible on the host.
    env_file:
      - ./backend/collaboration-service/.env

matching_service

import fetch from "node-fetch";
import { v4 as uuidv4 } from "uuid";

const createRoom = async ({ participants }) => {
  const url = "http://collaboration-service:4000/create-room"; // Using Docker service name
  const requestBody = {
    roomId: uuidv4(),
    participants: participants,
  };

  try {
    const response = await fetch(url, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify(requestBody),
    });

    if (!response.ok) {
      const errorText = await response.text();
      throw new Error(`Server error: ${response.statusText}, ${errorText}`);
    }

    const data = await response.json();
    return data;
  } catch (error) {
    console.error("Error creating room:", error.message);
    return { status: 500, message: error.message };
  }
};

export { createRoom };

collaboration_service

import express from "express";
import dotenv from "dotenv";
import cors from "cors";

dotenv.config();

const app = express();
app.use(express.json());

// Configure CORS to allow requests only from specific origins
const allowedOrigins = ['http://matching-service:3002']; // Origin of matching_service
app.use(cors({
  origin: function (origin, callback) {
    if (!origin || allowedOrigins.indexOf(origin) !== -1) {
      callback(null, true);
    } else {
      callback(new Error('Not allowed by CORS'));
    }
  }
}));

const Room = require("./models/Room");

app.post("/create-room", async (req, res) => {
  const { roomId, participants } = req.body;
  try {
    let existingRoom = await Room.findOne({ roomId });
    if (existingRoom) {
      return res.status(400).json({ message: "Room already exists" });
    }

    const newRoom = new Room({ roomId, participants });
    await newRoom.save();
    return res.status(201).json({ message: "Room created", room: newRoom });
  } catch (err) {
    return res
      .status(500)
      .json({ message: "Error creating room", error: err.message });
  }
});

const PORT = process.env.PORT || 4000;
app.listen(PORT, () => console.log(`Server running on port ${PORT}`));

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