初始化数据库失败，出现错误无法连接到`host=db user=database=`：拨号错误（拨号tcp xxxx：连接：连接被拒绝）

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

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())
        }
    }

healthcheck:
    test: ["cmd-shell", "pg_isready"]
    interval: 10s
    timeout: 5s
    retries: 5

depends_on:
  db:
    condition: service_healthy