Ubuntu 22.04下DotNet 7应用Docker部署后无法访问求助

我在Ubuntu 22.04系统上开发DotNet 7应用，本地执行dotnet run后可正常通过localhost:7222访问应用，但使用提供的Dockerfile构建镜像并映射5000端口运行容器后，无法在浏览器访问该应用，Windows环境下也出现相同问题。

本地运行日志 #

dotnet run
Building...
warn: Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer[8]
      The ASP.NET Core developer certificate is not trusted. For information about trusting the ASP.NET Core developer certificate, see https://aka.ms/aspnet/https-trust-dev-cert.
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: https://localhost:7222
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5222
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /home/fit/Desktop/webapp/Dental App

Dockerfile内容 #

# Multi stage Docker Image Build

# Build Stage
FROM mcr.microsoft.com/dotnet/sdk:7.0 AS build
WORKDIR /source
COPY . .
RUN dotnet restore "./Dental App.csproj" --disable-parallel
COPY . ./
RUN dotnet publish "./Dental App.csproj" -c release -o /app

# Serve Stage
FROM mcr.microsoft.com/dotnet/sdk:7.0
WORKDIR /app
COPY --from=build /app ./

EXPOSE 5000


ENTRYPOINT ["dotnet", "Dental App.dll"]

容器运行日志 #

$ docker container run --publish 5000:5000 appdental:latest
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Production
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /app

问题原因 #

容器日志显示应用仅监听localhost:5000，这意味着应用只能接收容器内部的请求，外部主机无法通过映射的端口访问。

解决方法 #

方法1：通过环境变量指定监听地址 #

修改Dockerfile的Serve阶段，添加环境变量让Kestrel监听所有IP：

# Serve Stage
FROM mcr.microsoft.com/dotnet/aspnet:7.0  # 推荐用runtime镜像替代sdk，减少镜像体积
WORKDIR /app
COPY --from=build /app ./

ENV ASPNETCORE_URLS=http://0.0.0.0:5000
EXPOSE 5000

ENTRYPOINT ["dotnet", "Dental App.dll"]

方法2：在启动命令中指定监听地址 #

直接修改ENTRYPOINT命令，添加--urls参数：

ENTRYPOINT ["dotnet", "Dental App.dll", "--urls=http://0.0.0.0:5000"]

额外优化 #

Serve阶段使用mcr.microsoft.com/dotnet/aspnet:7.0镜像而非sdk镜像，因为sdk包含编译工具，运行时不需要，能大幅减小镜像体积。

内容的提问来源于stack exchange，提问作者4tire