Keep getting the Error: getaddrinfo ENOTFOUND postgres when I try to connect to docker container

Question

I keep getting this error through my typeORM DataSource connection when I'm trying to connect to my dockerized postgres database.

docker-compose.yml:

  node_app:
    build: ./node
    container_name: node
    environment:
      - PGHOST=postgres
      - NODE_ENV=development
      - PORT=4000
    depends_on:
      postgres:
        condition: service_healthy
    command: sh -c "npm start"
    volumes:
      - ./node:/home/node/app:cached
    ports:
      - '4000:4000'
  postgres:
    image: postgres
    container_name: postgres
    restart: always
    environment:
      POSTGRES_DB: job_matching
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: password
    ports:
      - 5432:5432
    volumes:
      - ./pgdata:/var/lib/postgresql/data
      - ./db/init.sql:/docker-entrypoint-initdb.d/create_tables.sql
    networks:
      - postgres-db-network
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -d $${POSTGRES_DB} -U $${POSTGRES_USER}"]
      interval: 1s
      timeout: 5s
      retries: 10

app.ts:

const dataSource = new DataSource({
  type: 'postgres',
  host: process.env.PGHOST || 'localhost',
  port: 5432,
  username: 'postgres',
  password: 'password',
  database: 'job_matching',
  entities: ['src/models/**/*.ts'],
});

Error in docker:

Error during Data Source initialization Error: getaddrinfo ENOTFOUND postgres
at GetAddrInfoReqWrap.onlookupall [as oncomplete] (node:dns:118:26) {
  errno: -3008,
  code: 'ENOTFOUND',
  syscall: 'getaddrinfo',
  hostname: 'postgres'
}

What I have tried so far:

1. connect to the postgresql through the terminal with psql -h localhost --port 5432 -U postgres => worked !
2. check that the node app is started depends on postgres service healthiness
3. check that I have only one postgres service running on port 5432 with lsof -i :5432 => com.docke 27212 sbagherzadeh 329u IPv6 0x81fea2c6d7e20ca9 0t0 TCP *:postgresql (LISTEN)
4. check that I request the container name instead of localhost or 127.0.0.1
5. try to use a .env file instead of the env variables directly from the docker compose file.

I'm running out of solutions if someone can help please :) !

Answer 1

postgres is on the postgres-db-network but node_app is not. so they're not networked together. So they can't talk. Thus, docker does not expose their container names to each other as resolvable hostnames.