failed to initialize database, got error failed to connect to `host=db user= database=`: dial error-CodePudding

I am getting the failed to initialize error whenever I start up my docker container service.

version: '3'

services:
  app:
    container_name: api
    build:
      context: .
      dockerfile: local.Dockerfile
    ports:
      - "9090:9090"
      - "40000:40000"
    security_opt:
      - "seccomp:unconfined"
    cap_add:
      - SYS_PTRACE
    restart: on-failure
    environment:
      PORT: 9090
      DB_CONN: "postgres://admin:pass@db:5432/test?sslmode=disable"
    volumes:
      - .:/app
    depends_on:
      - db
    links:
      - db

  db:
    image: postgres
    container_name: db
    ports:
      - "5432:5432"
    environment:         
      POSTGRES_USER: "admin"
      POSTGRES_PASSWORD: "pass"
      POSTGRES_DB: "test"
      TZ: "UTC"
      PGTZ: "UTC"
    volumes:
      - ./tmp:/var/lib/postgresql/data

I am using air for live reload, please find the air.toml file

root="."
tmp_dir="tmp"

[build]
cmd="go build -gcflags=\"all=-N -l\" -o ./bin/main ."
bin="/app/bin"
full_bin="/app/bin/main"
log="air_errors.log"
include_ext=["go", "yaml"]
exclude_dir=["tmp"]
delay=1000

[log]
time=true


[misc]
clean_on_exit=true




func main() {
    Instance, err = gorm.Open(postgres.Open(conn), &gorm.Config{
            Logger: logger.New(
                log.New(os.Stdout, "", log.LstdFlags), logger.Config{
                    LogLevel: logger.Info,
                    Colorful: true,
                }),
        })
        if err != nil {
            panic("Cannot connect to DB"   err.Error())
        }
    }

The connection gets established if you save the code again and air live reload the appliation

CodePudding user response：

You need to wait until the postgres database has been initialized.

Have a look at https://docs.docker.com/compose/compose-file/compose-file-v3/#healthcheck

Add a healthcheck for db service

healthcheck:
    test: ["CMD-SHELL", "pg_isready"]
    interval: 10s
    timeout: 5s
    retries: 5

And change depend_on as below

depends_on:
  db:
    condition: service_healthy