Agfdhyk

I am working with a project that uses express as the server and postgres as the db to learn dockers.
the server depends on the db to be up.
The first time i use docker-compose up it all works fine but when i restart it
(docker-compose down and docker-compose up again) it says that something is wrong with the port

version: '3'

services:

  db:

    image: postgres:10

    ports:

      - "5433:5432"

    environment:

      POSTGRES_USER: 'Donald'

      POSTGRES_PASSWORD: 'Aa123456'

      POSTGRES_DB: 'twitter'



  backend:

    build: twitter

    ports: 

      - "3000:3000"

    depends_on: 

      - db

    environment:

      PGHOST: "db"

      PGPORT: '5432'

      PGDATABASE: 'twitter'

      PGUSER: 'Donald'

      PGPASSWORD: 'Aa123456'

The error

{ Error: connect ECONNREFUSED 172.19.0.2:5432

backend_1  |     at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1117:14)

backend_1  |   errno: 'ECONNREFUSED',

backend_1  |   code: 'ECONNREFUSED',

backend_1  |   syscall: 'connect',

backend_1  |   address: '172.19.0.2',

backend_1  |   port: 5432 }

ports before docker-compose down

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES

b000b9a02257        excer_backend       "node server"            5 minutes ago       Up 3 minutes        0.0.0.0:3000->3000/tcp   excer_backend_1

40ca65adcc46        postgres:10         "docker-entrypoint.s…"   5 minutes ago       Up 3 minutes        0.0.0.0:5433->5432/tcp   excer_db_1

after i use docker-compose down and see the ports its all clean and no open ports are left

Than i found something very interesting a when i used docker-compose up it always worked if i use ctr + c and use compose up again still work same when i restart docker but as soon as i use docker-compose down the error is shown.
I tried man combinations with restarting my docker and ctr + c and compose-up
all worked but as soon as i use docker-compose down it dosent work why is that ?

Most likely the DB is not up yet.

When you do docker-compose down, it deletes the container and since you aren't using a volume for persistence, the DB has to run through its init process again which will take a few seconds (and hence works when you ctrl+c and docker-compose up again).

Do note that depends_on doesn't wait until the DB is up. You will have to using something like wait-on for that in your backend container.

Another solution would be to use a volume mount for the DB container.