Data import fails during database initialize process

[ant-]

I'm trying to dockerize Django application with PostgreSQL database.
I'm stuck on data import during database initialization process.
To build a database container I do:
docker-compose up --build db

The process is starting and all seems to be well except some warnings like checkpoint happens too often and ERROR: canceling autovacuum task db_1_2e5b04cd80b3 | CONTEXT: automatic analyze of table

At the end I'm seeing the following:

db_1_2e5b04cd80b3 | waiting for server to shut down...LOG:  received fast shutdown request
db_1_2e5b04cd80b3 | .LOG:  aborting any active transactions
db_1_2e5b04cd80b3 | FATAL:  terminating autovacuum process due to administrator command
db_1_2e5b04cd80b3 | LOG:  autovacuum launcher shutting down
db_1_2e5b04cd80b3 | LOG:  shutting down
db_1_2e5b04cd80b3 | LOG:  database system is shut down
db_1_2e5b04cd80b3 |  done
db_1_2e5b04cd80b3 | server stopped
db_1_2e5b04cd80b3 | 
db_1_2e5b04cd80b3 | PostgreSQL init process complete; ready for start up.
db_1_2e5b04cd80b3 | 
db_1_2e5b04cd80b3 | LOG:  database system was shut down at 2019-07-04 13:12:44 UTC
db_1_2e5b04cd80b3 | LOG:  MultiXact member wraparound protections are now enabled
db_1_2e5b04cd80b3 | LOG:  database system is ready to accept connections
db_1_2e5b04cd80b3 | LOG:  autovacuum launcher started

But there is no any problems within importing data after container startup, like so:
psql -U postgres -h localhost woorder < 2-data.sql

docker-compose.yml

version: '3'

services:
  db:
    build:
      context: ./
      dockerfile: Dockerfile_db
    restart: always
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
      - POSTGRES_DB=postgres
      - PGDATA=/var/lib/postgresql/data
    volumes:
      - ./postgres-data:/var/lib/postgresql/data
      - .:/project
      - ./db-init-scripts:/docker-entrypoint-initdb.d
    ports:
      - 5432:5432
  backend:
    build: .
    command: python /backend/manage.py runserver 0.0.0.0:8081
    restart: always
    env_file:
      - .env
    volumes:
      - .:/backend
    ports:
      - 8081:8081
    depends_on:
      - db
    links:
      - db

1-schema.sql

CREATE USER woorder WITH PASSWORD 'pass';
CREATE DATABASE woorder;
GRANT ALL PRIVILEGES ON DATABASE woorder TO woorder;
ALTER ROLE woorder SET client_encoding TO 'utf8';
ALTER ROLE woorder SET default_transaction_isolation TO 'read committed';
ALTER ROLE woorder SET timezone TO 'UTC';

There is a 2-data.sql file which is 2.1Gb SQL dump under db-init-scripts directory.

Dockerfile

FROM python:3.6
ENV PYTHONUNBUFFERED 1
RUN mkdir /backend
WORKDIR /backend
ADD requirements.txt /backend/
RUN pip install -r requirements.txt
RUN pip install https://github.com/jasperlittle/django-rest-framework-docs/archive/master.zip
ADD . /backend/

Dockerfile_db

FROM postgres:9.6

RUN mkdir -p "$PGDATA" && chmod 700 "$PGDATA"

The question is why the import fails during database initialization?

UPDATE
I forgot to mention that saying "import fails" I mean that there are no data in the database, but it runs. As I said if I'll execute import after container goes up everything is ok.