"Error: Connection timeout" when connecting to Redis Docker instance

Question

I'm running my Node/Express app inside a Docker container, joined together with a Redis instance through Docker Compose. The problem is, when I try to connect the Node app with Redis (using this npm package, v^4.0.1), I get this error:

Error: Connection timeout
     at Socket.<anonymous> (/app/node_modules/@node-redis/client/dist/lib/client/socket.js:163:124)
     at Object.onceWrapper (node:events:509:28)
     at Socket.emit (node:events:390:28)
     at Socket.emit (node:domain:537:15)
     at Socket._onTimeout (node:net:501:8)
     at listOnTimeout (node:internal/timers:557:17)
     at processTimers (node:internal/timers:500:7)

If I run a separate Redis instance with docker run --name my-redis -p 6379:6379 -d redis and I use 127.0.0.1:6379 as the connection URL in Node it works. So I think it's something about Docker networking, but I can't find what.

This is my docker-compose.yaml:

version: "3.9" 
services:
  api:
    build: .
    volumes:
      - ./src/:/app/src/
    ports:
      - "8080:8080"
    environment:
      - NODE_ENV
  redis:
    image: "redis:6.2.6"

This is the Dockerfile for the Node app:

# base image
FROM node:16.13.0-alpine

# working directory
WORKDIR /app

# add binaries to $PATH
ENV PATH /app/node_modules/.bin:$PATH

# install and cache app dependencies
COPY package*.json ./
RUN npm install

# copy app files and build
COPY . .
RUN npm run build

# start app
CMD [ "npm", "start", "--ENV=${NODE_ENV}" ]

And this is the code I use for connecting to Redis in my Node app:

import { createClient } from "redis";    

(...)    

const client = createClient({ url: `redis://redis:6379` });

client.on("error", (error) => {
  throw error;
});

await client.connect();
const data = await client.get(customerId);
await client.quit();
return data;

Any help, please?

Thank you very much!