docker 中的端口映射不适用于 python 服务器

Question

我想用 sagemath 构建一个服务器，它应该接收代码，执行它并发回结果。 SageMath 有一个 python 接口，我认为可以用它来实现。我不太了解 python，但我在这里 https://ask.sagemath.org/question/23431/running-sage-from-other-languages-with-higher-performance/ 找到了一个很好的起点。问题是我想在 docker 容器中运行这个，所以只映射端口，但这似乎不起作用。

我更改了 python 文件以将其调整到较新的版本：

import socket
import sys
from io import StringIO
from sage.all import *
from sage.calculus.predefined import x
from sage.repl.preparse import preparse


SHUTDOWN = False
HOST = 'localhost'
PORT = 8888
MAX_MSG_LENGTH = 102400

# Create socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
print('Socket created')

# Bind socket to localhost and port
try:
  s.bind((HOST, PORT))
except (socket.error , msg):
  print('Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1])
  sys.exit()

print('Socket bind complete')

# Start listening on socket
s.listen(10)
print('Socket now listening')

# Loop listener for new connections
while not SHUTDOWN:
  # Wait to accept a new client connection
  conn, addr = s.accept()
  print('Connected with ' + addr[0] + ':' + str(addr[1]))

  # Receive message from client
  msg = conn.recv(MAX_MSG_LENGTH)
  if msg:
    if msg == "stop":
      SHUTDOWN = True
    else:
      parsed = preparse(msg)
      if parsed.startswith('load') or parsed.startswith('attach'):
        os.system('sage "' + os.path.join(os.getcwd(), parsed.split(None, 1)[1]) + '"')
      else:
        # Redirect stdout to my stdout to capture into a string
        sys.stdout = mystdout = io.StringIO()

        # Evalutate msg
        try:
          eval(compile(parsed,'<cmdline>','exec'))
          result = mystdout.getvalue() # Get result from mystdout
        except Exception as e:
          result = "ERROR: " + str(type(e)) + " " + str(e)

        # Restore stdout
        sys.stdout = sys.__stdout__

        # Send response to connected client
        if result == "":
          conn.sendall("Empty result, did you remember to print?")
        else:
          conn.sendall(result)

  # Close client connection
  conn.close()

# Close listener
s.close()

然后我创建了一个脚本运行它

#!/bin/bash

/usr/bin/sage -python /var/app/sage-server.py

之后我创建了 Dockerfile 来安装 SageMath

FROM ubuntu:20.04

COPY src/ /var/app

RUN apt-get update \
    && DEBIAN_FRONTEND="noninteractive" TZ="Europe/London" apt-get -y install tzdata \
    && apt-get install sagemath -y

WORKDIR /var/app
    
RUN ["chmod", "+x", "/var/app/server.sh"]

CMD ["/var/app/server.sh"]

最后是一个 docker-compose 文件，用于自动映射并将其包含到主项目中

version: '3'

services:
  sage-server:
    build: .
    volumes: 
      - ./src:/var/app
    ports:
      - "9999:8888"

所有部分执行良好且没有任何错误（在 ubuntu 上）。我什至看到当我进入容器时使用了该端口，但主机系统中未使用端口 9999。

你们有什么想法吗？

Answer 1

根据@David Maze 的建议，您需要在 0.0.0.0 上公开才能在容器中访问。

HOST = '0.0.0.0'

然后你会遇到一些问题：

preparse 期待 str 所以你需要解码收到的字节：
```
msg = conn.recv(MAX_MSG_LENGTH).decode('utf-8')
```
StringIO 是直接导入的，所以不需要前缀 io.：
```
sys.stdout = mystdout = StringIO()
```
你需要发回一个字节，但结果是一个str，所以你需要编码：
```
conn.sendall(result.encode('utf-8'))
```

可以改进 Dockerfile (https://docs.docker.com/develop/develop-images/dockerfile_best-practices/):

FROM ubuntu:20.04

# First install dependencies so next builds will reuse docker build cache
# Use `--no-install-recommends` to minimize the installed packages
# Clean apt data
RUN apt-get update \
    && DEBIAN_FRONTEND="noninteractive" TZ="Europe/London" apt-get -y install tzdata \
    && apt-get install --no-install-recommends sagemath -y \
    && rm -rf /var/lib/apt/lists/*

# Copy changing data as late as possible to use docker build cache
COPY src/ /var/app
WORKDIR /var/app

# Explicit the listening ports
EXPOSE 8888

# No need for a wrapper script for simple command (and workaround chmod issue)
ENTRYPOINT ["/usr/bin/sage", "-python", "/var/app/sage-server.py"]

由于源代码的构建时副本在运行时被卷装载覆盖，权限必须在主机端正确（构建 RUN chmod +x 没有效果在运行次挂载的文件上）

docker 中的端口映射不适用于 python 服务器

Port mapping in docker doesn't work for python server

python

sockets

sage

docker

docker-compose