python - --extra-index-url が docker ファイルで機能しない

Question

次のdocker-compose.ymlを使用してローカルpypiserverをセットアップしましたが、直接使用すると機能します

pip install -r requirements.txt --extra-index-url http://127.0.0.1:8082

ただし、Dockerfile で同じコマンドを使用しようとすると、機能しません。私が作成したファイルは次のファイルです。

Dockerfile:

FROM python:3
ENV PYTHONUNBUFFERED=1
ARG PIP_EXTRA_INDEX_URL
WORKDIR /code
COPY requirements.txt /code/
RUN echo "${PIP_EXTRA_INDEX_URL}"
RUN pip install -r requirements.txt $PIP_EXTRA_INDEX_URL
COPY . /code/

docker-compose.yml

version: "3.9"

services:
  db:
    image: postgres
    volumes:
      - ./data/db:/var/lib/postgresql/data
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
  web:
    build:
      context: .
      args:
        - PIP_EXTRA_INDEX_URL=http://127.0.0.1:8082/simple/
    command: python manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    ports:
      - "8800:8000"
    depends_on:
      - db

実行しようとするdocker-compose up と、次のエラーが発生します。

Looking in indexes: https://pypi.org/simple, http://127.0.0.1:8082/simple/
Collecting http://127.0.0.1:8082/simple/
  WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPConnection object at 0x7f7407596df0>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/
  WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPConnection object at 0x7f7407596b20>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/
  WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPConnection object at 0x7f74089dcf70>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/
  WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPConnection object at 0x7f74089dca60>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/
  WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPConnection object at 0x7f74089dcdf0>: Failed to establish a new connection: [Errno 111] Connection refused')': /simple/
ERROR: Could not install packages due to an OSError: HTTPConnectionPool(host='127.0.0.1', port=8082): Max retries exceeded with url: /simple/ (Caused by NewConnectionError('<pip._vendor.urllib3.connection.HTTPConnection object at 0x7f74089dcac0>: Failed to establish a new connection: [Errno 111] Connection refused'))

ERROR: Service 'web' failed to build : The command '/bin/sh -c pip install -r requirements.txt $PIP_EXTRA_INDEX_URL' returned a non-zero code: 1

このコードに欠落している構成はありますか?