PG Pool is not working inside Docker container - node.js

Question

I am running a PERN application and currently trying to dockerize it. When I run the database as a container and the server and client locally I have no issues. However, when I containerize the server, client, and database respectively, I am unable to make requests. It results in 404 errors. This is the same behavior that occurs when I pass pool the wrong port or host. So I'm wondering if somehow I am giving the wrong host and/or port to pool or if I should change it when I containerize it.
This is the Pool Instance
const Pool = require('pg').Pool
const pool = new Pool({
user: 'docker',
password: 'docker',
host: "localhost",
port: 4000,
database: "docker"
})
This is part of the rest api in the server:
const express = require("express")
const router = express.Router()
const pool = require('../database/database.js')
router.get("/:login", async (req, res) => {
try {
let loginReq = JSON.parse(decodeURIComponent(req.params.login))
const user = await pool.query(
"SELECT user_id,first_name,last_name,email FROM \"user\" where email = $1 and password = $2",
[loginReq.email, loginReq.password]
)
if(user.rows.length) {
res.json(user.rows[0])
} else {
throw new Error('User Not Found')
}
} catch (err) {
res.status(404).json(err.message)
}
})
This is each of my dockerfiles for my client, server, and database
Client:
FROM node:18-alpine
WORKDIR /app
COPY . .
RUN npm install --production
CMD ["npm","start"]
EXPOSE 3000
Server:
FROM node:18-alpine
WORKDIR /app
COPY . .
RUN npm install --production
CMD ["node","index.js"]
EXPOSE 5000
Database;
FROM postgres:15.1-alpine
COPY init.sql /docker-entrypoint-initdb.d/
This is my docker-compose.yml
version: "3.8"
services:
client:
build: ./client
ports:
- "3000:3000"
restart: unless-stopped
server:
build: ./server
ports:
- "5000:5000"
restart: unless-stopped
database:
build: ./database
ports:
- "4000:4000"
environment:
- POSTGRES_USER=docker
- POSTGRES_PASSWORD=docker
- POSTGRES_DB=docker
- PGPORT=4000
volumes:
- kurva:/var/lib/postgresql/data
restart: unless-stopped
volumes:
kurva:
I don't understand why the behavior would be different between containerizing the server and running it locally when they all use the same ports. I have tried messing with the host and changing it to 0.0.0.0 but that did not help. Any help would be appreciated!

Answer 1

I found that it was a host issue and I needed to change the host accessed in the pool to the service name. Additionally, I needed to add that the server depends on the database service.
This is the updated pg pool:
const pool = new Pool({
user: 'docker',
password: 'docker',
host: "database",
port: 4000,
database: "docker"
})
This is the updated docker-compose.yml
version: "3.8"
services:
client:
build: ./client
ports:
- "3000:3000"
restart: unless-stopped
server:
build: ./server
ports:
- "5000:5000"
depends_on:
- database
restart: unless-stopped
database:
build: ./database
ports:
- "4000:4000"
environment:
- POSTGRES_USER=docker
- POSTGRES_PASSWORD=docker
- POSTGRES_DB=docker
- PGPORT=4000
volumes:
- kurva:/var/lib/postgresql/data
restart: unless-stopped
volumes:
kurva: