docker 运行不起作用，但 docker 编写工作正常

Question

i try to run fastapi application with docker i create this Dockerfile

FROM python

WORKDIR /code

ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

COPY Pipfile Pipfile.lock /code/

RUN pip install pipenv && pipenv install --system

COPY . /code/

CMD ["uvicorn", "blog.main:app"]

and run it with

docker run -p 8000:8000

the log says the application run on 127.0.0.1:8000 but i can't access the application on http://localhost:8000

i create docker compose like this

services:
  web:
    build: .
    command: uvicorn blog.main:app --reload --workers 1 --host 0.0.0.0 --port 8000
    ports:
      - "8000:8000"

and remove the CMD from Dockerfile and again have same log message application running at 127.0.0.1:8000 but this time i can access my application via http://localhost:8000

can someone explain whats wrong with my first method?

Answer 1

In docker-compose you are overriding the CMD with correct way of exposing the host and port to outside world. In your Dockerfile change CMD ["uvicorn", "blog.main:app"] to CMD ["uvicorn", "blog.main:app", "--host", "0.0.0.0", "--port", "8000"] docker run should work

Answer 2

You do not want the application listening on 127.0.0.1:8000. You want it listening on 0.0.0.0:8000 (as the second version is). I am not familiar with the program you are running, but there must be some way to tell it the host to listen on.

When a server binds to localhost (127.0.0.1), it accepts connections only from that machine. (The client also has to use localhost, not the actual IP address.) Since to docker, the host machine is a different machine, the connection is not allowed.