Golang + postgres + docker: 拨打 tcp 172.18.0.2:5432: connect: connection refused

Question

I'm trying to make a docker-compose from my golang app and postgres database. Here is the code for db initialization:

db, err := repository.NewPostgresDB(repository.Config{
        Host:     os.Getenv("DB_HOST"),
        Port:     viper.GetString("db.port"),
        Username: viper.GetString("db.username"),
        DBName:   viper.GetString("db.dbname"),
        SSLMode:  viper.GetString("db.sslmode"),
        Password: os.Getenv("DB_PASSWORD"),
    })

I take host and password from.env:

DB_PASSWORD=qwerty
DB_HOST=db

and from.configs:

port: "8000"

db:
  username: "postgres"
  port: "5432"
  dbname: "postgres"
  sslmode: "disable"

Docker file is not interesting i guess:

FROM golang:1.19-buster

RUN go version
ENV GOPATH=/

COPY ./ ./

# install psql
RUN apt-get update
RUN apt-get -y install postgresql-client


# build go app
RUN go mod download
RUN go build -o balance-app ./cmd/main.go

CMD ["./balance-app"]

Docker-compose has enviromental intructions as well:

version: '3.8'

services:
  balance-app:
    build: ./
    command: ./balance-app
    ports:
      - 8000:8000
    depends_on:
      - db
    environment:
      - DB_PASSWORD=qwerty
      - DB_HOST=db


  db:
    restart: always
    image: postgres:latest
    volumes:
      - ./.database/postgres/data:/var/lib/postgresql/data
    environment:
      - POSTGRES_PASSWORD=qwerty
    ports:
      - 5432
    healthcheck:
      test: [ "CMD-SHELL", "pg_isready -U postgres" ]
      interval: 3s

I tried to change ports, tried to change host to localhost like it worked on my linux without docker compose(but docker put postgres to 172...), but it always the same error. Will be glad if someone could help me, thanks

Answer 1

The balance-app does not wait the db. You should probably look at https://docs.docker.com/compose/startup-order/ and use condition: service_healthy in balance-app part.

version: '3.8'
services:
  db:
    image: postgres:latest
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
    ports:
      - 5432:5432
    healthcheck:
      test: [ "CMD-SHELL", "pg_isready -U postgres" ]
      interval: 3s
  balance-app:
    ...
    depends_on:
      db:
        condition: service_healthy