部署Docker应用至Google Cloud Run（端口8000）出现404错误求助

部署应用到Google Cloud Run后访问出现404错误（错误页面截图如下），但应用在本地通过docker-compose运行完全正常。

docker-compose.yml配置 #

version: '2'

services:
  redis:
    image: 'redis:3.0-alpine'
    command: redis-server --requirepass devpassword
    volumes:
      - 'redis:/var/lib/redis/data'
    ports:
      - '6379:6379'

  website:
    build: .
    command: >
      gunicorn -c "python:config.gunicorn" --reload "snakeeyes.app:create_app()"
    env_file:
      - '.env'
    volumes:
      - '.:/snakeeyes'
    ports:
      - '8000:8000'

  celery:
    build: .
    command: celery worker -l info -A snakeeyes.blueprints.contact.tasks
    env_file:
      - '.env'
    volumes:
      - '.:/snakeeyes'

volumes:
  redis:

Dockerfile配置 #

FROM python:3.7.5-slim-buster

RUN apt-get update && apt-get install -qq -y \
    build-essential libpq-dev --no-install-recommends

ENV INSTALL_PATH /snakeeyes
RUN mkdir -p $INSTALL_PATH

WORKDIR $INSTALL_PATH

COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt

COPY . .
RUN pip install --editable .

# CMD gunicorn -b 0.0.0.0:8000 --access-logfile - "snakeeyes.app:create_app()"
CMD gunicorn -c "python:config.gunicorn" "snakeeyes.app:create_app()"

已将Cloud Run容器端口设置为8000并允许公网请求，尝试执行以下命令：

curl -v https://xxx-q42lz4rc5a-uc.a.run.app/

返回结果：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<title>404 Not Found</title>
<h1>Not Found</h1>
<p>The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.</p>

Cloud Run请求日志：

{
httpRequest: {
latency: "0.003104020s"
protocol: "HTTP/1.1"
remoteIp: "189.102.84.133"
requestMethod: "GET"
requestSize: "395"
requestUrl: "https://growthgeeks-q42lz4rc5a-uc.a.run.app/"
responseSize: "870"
serverIp: "216.239.32.53"
status: 404
userAgent: "Mozilla/5.0 (Windows NT; Windows NT 10.0; en-US) WindowsPowerShell/5.1.22621.963"
}
insertId: "647383350005b235faf2d636"
labels: {
instanceId: "004d9db0be8fbe61fa21785209ea77b301b910f3d3a85b98070364c3b7f349c0afa3801798354327d2c09ecf8a343e703ad66f1343b77e2e753b9b65110486dc4a"
}
logName: "projects/roas-164016/logs/run.googleapis.com%2Frequests"
receiveTimestamp: "2023-05-28T16:37:09.377173714Z"
resource: {
labels: {
project_id: "roas-164016"
revision_name: "growthgeeks-00007-sqg"
location: "us-central1"
configuration_name: "growthgeeks"
service_name: "growthgeeks"
}
type: "cloud_run_revision"
}
severity: "WARNING"
spanId: "8423610564014712292"
timestamp: "2023-05-28T16:37:09.368517Z"
trace: "projects/roas-164016/traces/8a57dc8aba186cf525e63daa0fc2b6a1"
traceSampled: true
}

• 检查Gunicorn监听配置
  当前Dockerfile使用config.gunicorn配置文件启动Gunicorn，务必确认该配置里的bind参数设置为0.0.0.0:8000。Cloud Run要求服务必须监听0.0.0.0而非localhost，否则外部请求无法到达应用。如果配置文件里没指定bind，直接修改Dockerfile的CMD命令，显式绑定地址：

  CMD gunicorn -b 0.0.0.0:8000 -c "python:config.gunicorn" "snakeeyes.app:create_app()"
  

• 验证应用路由配置
  本地正常但部署后404，大概率是生产环境下的路由问题。检查snakeeyes.app:create_app()中是否正确注册了根路径/的视图函数，确认没有环境变量导致路由前缀变更，或者生产环境下未加载必要的路由模块。

• 本地镜像独立测试
  不要依赖docker-compose的本地卷挂载，直接构建镜像并运行，模拟Cloud Run的运行环境：

  docker build -t snakeeyes .
  docker run -p 8000:8000 --env-file .env snakeeyes
  curl http://localhost:8000/
  

  如果此时也返回404，说明镜像构建有问题——比如代码未完整复制、依赖安装不彻底，或者启动命令缺失必要参数。

• 同步Cloud Run环境变量
  部署时Cloud Run不会自动加载.env文件，需要手动在Cloud Run服务配置中添加所有.env里的环境变量。如果应用依赖某些变量初始化路由或数据库连接，缺失这些变量会导致服务无法正常响应请求。

• 开启应用日志排查
  修改Gunicorn启动命令，添加日志输出参数，让应用日志输出到stdout/stderr，这样Cloud Run就能捕获到详细的请求和错误信息：

  CMD gunicorn -b 0.0.0.0:8000 -c "python:config.gunicorn" --access-logfile - --error-logfile - "snakeeyes.app:create_app()"
  

  查看Cloud Run的应用日志，确认请求是否到达Gunicorn，以及应用内部是否有报错。

内容的提问来源于stack exchange，提问作者Filipe Ferminiano