Docker 使用“同步”操作来编写监视，并给出错误“文件存在”。 “重建”工作正常

Question

我正在尝试使用

docker compose watch

配置 Django 项目，以将代码更改同步到容器化 Django 应用程序中。

撰写文件如下：

include:
  - compose-db-dev.yaml
services:
  webapp:
    environment:
      - DJANGO_SETTINGS_MODULE=app.settings.dev
    build: .
    ports:
      - 3000:8080
    develop:
      watch:
        - action: sync
          path: .
          target: /app
    depends_on:
      db:
        condition: service_healthy

将操作设置为“同步”时，出现以下错误：

Syncing webapp after changes were detected:
  - /home/jb/myapp/main/views.py
itar: app/main/views.py: Cannot open: File exists
tar: Exiting with failure status due to previous errors
WARN[0023] Error handling changed files for service webapp: 1 error occurred:
        * copying files to 47b692a96cf0e7b8edd3922f27aaa05fd63d511176cfe1362126828a28d9f030: exit code 2

将手表操作设置为

rebuild

时不会出现此错误。一切正常，正在更新应用程序。然而，重建图像需要几秒钟的时间，这不是理想的工作流程资源。

据我所知，更改 Django 应用程序中的视图不需要“重建”服务，因此我认为同步操作是更好的选择。预计“文件存在”（同步的是现有文件），那么为什么我会收到此错误？

Answer 1

它看起来像是 compose watch 中的一个错误，要解决此问题，您需要以 root 身份运行容器，错误问题：https://github.com/docker/compose/issues/11304

因此，不要直接使用

USER myappuser

，但最好在 Dockerfile 中创建一个“dev”阶段，并仅在其中使用 root，这样在生产中运行的“prod”阶段仍然可以使用非 root “应用程序用户”。USER root

为了在 compose.yaml 中反映这一点，您需要为构建设置设置 

# syntax=docker/dockerfile:1
    
ARG PYTHON_VERSION=3.10.12
FROM python:${PYTHON_VERSION}-slim as prod

# Prevents Python from writing pyc files.
ENV PYTHONDONTWRITEBYTECODE=1

# Keeps Python from buffering stdout and stderr to avoid situations where
# the application crashes without emitting any logs due to buffering.
ENV PYTHONUNBUFFERED=1

WORKDIR /app

# Create a non-privileged user that the app will run under.
# See https://docs.docker.com/go/dockerfile-user-best-practices/
ARG UID=10001
RUN adduser \
    --disabled-password \
    --gecos "" \
    --home "/nonexistent" \
    --shell "/sbin/nologin" \
    --no-create-home \
    --uid "${UID}" \
    appuser

# Download dependencies as a separate step to take advantage of Docker's caching.
# Leverage a cache mount to /root/.cache/pip to speed up subsequent builds.
# Leverage a bind mount to requirements.txt to avoid having to copy them into
# into this layer.
RUN --mount=type=cache,target=/root/.cache/pip \
    --mount=type=bind,source=requirements.txt,target=requirements.txt \
    python -m pip install -r requirements.txt

# Switch to the non-privileged user to run the application.
USER appuser

# Copy the source code into the container.
COPY ./mydjangoapi .

# Expose the port that the application listens on.
EXPOSE 8000

# Run the application.
# CMD gunicorn 'myapp:app' --bind=0.0.0.0:8000
CMD gunicorn mydjangoapi.wsgi:application --bind=0.0.0.0:8000

FROM prod as dev

# switch to root because docker compose watch bug
USER root

CMD gunicorn mydjangoapi.wsgi:application --bind=0.0.0.0:8000

：

target: dev